Wet-pit mining impact assessment coastal zone of Puerto Rico

[From the U.S. Government Printing Office, www.gpo.gov]

A&
TN
291.5
R85
1988

WET-PIT MINING IMPACT ASSESSMENT:
COASTAL ZONE OF PUERTO RICO

Andrea Handler Ruiz and Rojeanne Salles O'Farrill

Department of Natural Resources
P.O. Box 5887
Puerta de Tierra
San Juan, P. R. 00906

Prepared for:

Office of Coastal Resources Management (OCRM)
National Oceanic and Atmospheric Administration (NOAA)

Task 7.2
May 1988

SUMMARY

In Puerto Rico, coastal zone sand deposits are exploited
basically to satisfy aggregate demand by the
construction industry. Since availability of inland
deposits above the water-table have been almost
exhausted, mining practices have extended below this
level, developing wet-pits. This study documents coastal
zone wet-pit sand mining and examines the impacts of
these operations on ecosystems and ground-water
hydrology. Twenty wet-pit mining operations, at various
stages of development, were identified. Three sites,
representing different coastal ecological zones, were
chosen for complete study. Mining history, land use,
hydrology, geology, soils, flora and fauna are described
for these sites. Flora and/or fauna are described for
four additional sites. Among the findings, this study
suggests that: 1) wet-pit mining locally affects ground-
water hydrology by changing flow patterns, lowering
ground-water levels on dune areas and displacing
salt/fresh water interface; 2) backfill material used to
restore the site will not severely alter the ground-
water system as long as it has similar hydraulic
properties as the original extracted sand; 3) mining
processes directly affect the ecological succesion of
plant and animal populations; 4) since restoration is
not aimed towards the recovery or development of
wildlife habitat there is a valuable loss of ecological
environments. Recommendations to better evaluate
extraction applications, understand the potentially
adverse environmental effects of wet-pit mining and
minimize coastal zone impacts are strongly suggested be
applied.

RECOMMENDATIONS

In Puerto Rico, the emphasis on construction

presses the aggregate production industry for continued

supply of prime material. Coastal zone deposits are

exploited to satisfy the demand for sand. Since

availability of inland deposits above the water-table

have been almost exhausted, mining practices have

extended below this level. Because there exists a

significant untapped sand reserve below the water-table,

it is expected that future resource demand will require

the mining of these deposits. Therefore, to: (1)

better evaluate extraction applications, (2) understand

the operation's potentially adverse environmental

effects, and (3) minimize coastal zone impacts, the

implementation of the following recommendations to

sustain, modify or supplement current regulations are

strongly suggested:

1. Pertinent application requirements for this type
of operation should be formulated by an inter-
disciplinary Puerto Rico Department of Natural Resources
(PR DNR) committee and added to the existing mining
regulation.

2. With the objective of evaluating site conditions
for mining (resource availability and potential impact)
the following should be required:

a. A detailed mining plan,
outlining extraction, backfilling and
restoration procedures;

b. A topographic map, preferably
at a scale of 1:500 and with 0.5m
contour intervals, with representative
cross sections. The existing land
levels, proposed mining and res-
toration levels should be clearly
indicated;

c. Representative boring profiles
with lithologic descriptions and
water-table indications;

d. A hydrologic/hydraulic study
of the proposed extraction site
indicating potential changes in:
regulatory (100YR) flood level,
localized surface drainage, storm wave
swash, and subsurface hydrology in
response to the proposed mining and
mitigation procedures;

e. Samples of the material to be
mined and proposed for backfill with
their respective hydraulic properties.

3. Simple monitoring wells should be installed in a
site to observe ground-water conditions before, during
and after mining.

4. Extractions below the water-table should keep a
significant buffer zone from mangroves and dunes.
Regions further inland from the coast are ecologically
more appropiate for mining.

5. Systematic field evaluations should be conducted
by trained personnel to verify operational procedures
and enforce the established regulations.

6. As in similar extraction activities elsewhere
(DuBois and Towle, 1985), pre and post mining site
surveys and impact assessments should be required for
all sites. The literature received offers guidelines
for this purpose.

7. It is recommended that wet-pits be backfilled as
a step towards reestablishing previous ground-water flow
conditions. Backfill material used should have similar
hydraulic properties as the original extracted sand in
order to minimize distortion in ground-water flow
patterns. Wet-pits should also be backfilled and the
mining site restored for safety and land reclamation
reasons. If wet-pits are to be left open, they should
be managed to support wildlife and/or safe recreational
environments.

8. The PR DNR should establish criteria to define
restoration procedures according to projected land uses.
Specific site evaluations should be conducted to
determine the most appropiate final land levels
compatible with future developments based on
requirements of law and interagency agreements.

9. Restorations should meet among others, the
following main objectives (Morrison, 1982):

a. Prevention or reduction of
wind and water erosion;

b. Provision of food and cover
for a variety of animal species;

c. Improvement of the visual or
aesthetic quality through refores-
tation.

10. Due to the high cost and intended purpose of
the Performance Bond, the PR DNR should take measures to
execute the bonds to ensure steps for adequate
restoration of extraction sites. Otherwise, this
requirement results academic.

11. Monitoring should be continued in the active
operations where test wells have been installed. This
would provide additional data on ground-water behavior
as mining progresses.

12. Findings from this study provide valuable
information on coastal zone wet-pit mining impact.
Systematic observations should be continued in order to
compile a reliable data bank on potential and observed
local environmental impacts. Evaluation of immediate,
long-term, and cummulative effects can then be used to
prepare technically and politically objective public
policy stategies.

CONTENTS

Page

Summary ............................................ ii

Recommendations .................................... iii

Figures ............................................ viii

Tables ............................................. ix

Appendixes ......................................... ix

Acknowledgments .................................... x

j
1.0 Introduction .................................. 1

2.0 Legal Aspects .................................. 9

3.0 Mining Processes and Impacts ................... 12

4.0 Methods
4.1 Site selection ...... 18
4.2 Complete monitoring sites .... ............ 18
4.3 Partial monitoring sites ................... 20
4.4 Literature search .......................... 21

5.0 Island-wide Inventory .......................... 22

6.0 Complete Monitoring Sites
6.1 Camuy
6.1.1 General information .................. 31
6.1.2 Mining history ....................... 32
6.1.3 Geology and soils .................... 34
6.1.4 Hydrology ............................ 36
6.1.5 Flora ................................ 37
6.1.6 Fauna ................................ 40
6.2 Aguada
6.2.1 General information .................. 52
6.2.2 Mining history ....................... 53
6.2.3 Geology and soils .................... 55
6.2.4 Hydrology ............................ 56
6.2.5 Flora ................................ 57
6.2.6 Fauna ................................ 60

CONTENTS (Cont.)

Page

6.3 Ponce
6.3.1 General information .................. 75
6.3.2 Mining history ....................... 76
6.3.3 Geology and soils .................... 78
6.3.4 Hydrology ............................ 80
6.3.5 Flora ................................ 80
6.3.6 Fauna ................................ 84

7.0 Partial Monitoring Sites
7.1 Loiza
7.1.1 General information .................. 104
7.1.2 Mining history and uses .............. 105
7.1.3 Flora .............. 0000.0 ............ 105
7.1.4 Fauna ..... o .......................... 106

8.0 Impacts on Wildlife Habitat ........ o ........... 110

9.0 Summary of Findings and Conclusions ............ 112

Bibliography ............................. o ......... 115

FIGURES

Figure Page

1 Anatomy of a typical beachfront with
coastal and maritime zone boundaries ....... 2

2 Inventory map of extraction sites .......... 23

3 Location of sand extraction sites .......... 30

4 Location of Camuy site (Pit No. 7) ......... 42

5 Soil and Geologic maps of Camuy site ....... 43

6 Vegetation maps of Camuy site .............. 44

7 Cross section illustrating changes in
plant association at Camuy site ............ 45

7a Post-mining cross section
7b Post-mining cross section
7c Pre-mining cross section
W
8 Location of Aguada site (Pit No. 9) ........ 62

9 Soil and Geologic maps of Aguada site ...... 63

10 Vegetation maps of Aguada site ............. 64

11 Cross section illustrating changes in
plant association at Aguada site ........... 65

lla Post-mining cross section
11b Post-mining cross section
11c Pre-mining cross section

12 Location of Ponce site (Pit No. 16) ........ 88

13 Soil and Geologic maps of Ponce site ....... 89

14 Vegetation maps of Ponce site .............. 90

15 Cross section illustrating changes in
plant association at Ponce site ............ 91

15a Pre-mining cross section
15b Post-mining cross section

Viii

FIGURES (Cont.)

Figure Page

16 Location of Loiza sites
(Pits No. 2, 3, 4) ......................... 108

17 Vegetation map of Loiza sites .............. 109

TABLES

Table

1 List of inventory sites and wet-pit
status code ................... 0 ........... 24

2 First permi.t date authorizing wet-pit
extraction ................................ 28

APPENDIXES

Appendix

I "Note to the file" authorizing extrac-
tions below the water-table,
March 12, 1981 ........................... 119

Ii Planning Board letter dated
June 24, 1980 ............................ 120

III Planning Board letter dated
November 22, 1985 ........................ 121

IV Outline: Task 7.2 ........................ 122

V Progress Report: General Hydrogeology
of Selected Coastal Sand Extraction
Sites in Puerto Rico ..................... 123

Vi Geologic and Soil Nomenclature ........... 124

ACKNOWLEDGMENTS

We gratefully acknowledge the collaboration given
by the following co-workers of the Scientific Area
during the different stages of this study: Evangelina
Silva, Walter Cardona, Luz. M. Cruz, and Elise Agosto
who worked on the drawings; Julio Toro for the aerial
photo interpretations and land photography; Vicente
Quevedo, Pedro Ortiz, Carlos Diaz, BArbara Cintr6n, and
Manuel Rivera for their technical advice; Iris Corujo
and William Ortiz for doing the experimental fishing;
Evangelina Silva and Walter Cardona for word-processing;
BArbara Cintr6n and Carlos Diaz provided editing
suggestions. Particular appreciation is given to Gregory
Morris for editing the final draft of this report. In
addition, we appreciate the cooperation and valuable
assistance of the USGS, Water Resources Division, in
carrying out this project through our interagency
aggreement.

1.0 INTRODUCTION

Puerto Rico's coastal zone, which has been defined

to extend 1km inland (PR CMP, 1978), has historically

been an important source of sand for use in the

construction industry.for several reasons:

Accessibility: Topographically low and level
terrain facilitates road preparation and transportation.
Low population density allows a certain flexibility in
site choices.

Availability: Deposits occur in known accretional
environments with economically attractive storage
capacities and resource renewal potential.

Minimum Equipment Requirements: Loose, uncemented
deposits (in most cases) facilitate removal, preparation
and dispatching (often without a sifting or storage
phase).

Cleanliness: Typically, coastal sand requires only
simple sifting techniques for sorting, ranging from a
wide fixed mesh to vibrating belt equipment. Water is
not employed and there is no need for establishing
sedimentation ponds.

Market: High sand quality (varied grain sizes, low
CaC03 and humus content) makes it attractive for a wide
range of uses that include: the preparation of cement
mix, cement blocks and pipes, road asphalt and
plastering sand.

Coastal sand mining takes place in the intertidal

zone, dunes, backdune and areas further inland (Fig.

1). Mining procedures extend from simple hand shoveling

into awaiting trucks to complex set-ups involving

various types of heavy equipment. Large extraction

operations focus mainly on the backdune zone and inland

COASTAL Z 0 N E I KM I N L A N D FROM LOW WATERLINE AND 3 MILES OF

MARITIME ZONE (M Z)

BACKDUNE
AREA HIG H
DUNE WATER LOW
LINE LINE WATERLI

INTERTIDAL
DUNE Z 0 N E
BERM (LIGHT
I N L A N D A R E A
DRY)

.............. .
X.

...............
...............
................. .......
.............. .. .
................. ..
............. ...

FIG.l. ANATOMY OF A' TYPICAL BEACHFRONT WITH COASTAL AND MARITIME ZC
BERM
..........
..........
..............

areas, and involve shallow surface scraping, up to one

meter above the water-table, and open pit excavations

up to four meters below the water-table (wet-pits).

The PR DNR is the government agency responsible for

monitoring mining activities, among them sand extraction

from the coastal zone. Direct supervision is rendered

by personnel from one of the seven corresponding PR DNR

regions. Time, experience and an increased awareness of

the potential impacts generated by the mining process

have permitted improvements in extraction techniques,

methodologies, systematization of permit evaluations and

the implementation of more detailed technical evaluation

procedures. Nevertheless, these improvements have not

been uniformly applied to all permit applications or

active operations.

The economic value of the extraction industry in

Puerto Rico has not been properly appraised. Complete

data on the total quantity of materials mined to date

from the island's tapped deposits, including those from

the coastal zone, has not been compiled. Extractors are

not required to report the actual amounts of sand mined,

except when mining activities take place in public lands

under the jurisdiction of the PR DNR (i.e. rivers,

intertidal zone, submarine areas) in which case, a

royalty to the government has to be paid. In particular,

wet-pit operations focused in this study, are not

subject to royalty payments. Therefore,,a reliable total

volume of sand mined each year from the coastal zone

through wet-pit development is unavailable.

Historically, the short term economic gains

associated with sand mining operations have generally

overshadowed both short and long term environmental

impacts. As a result, management approaches have been

exploitive and have not properly integrated product

demand, site selection and mining practices with

limitations on the rate of resource replenishment and

with potential environmental disturbances.

The magnitude of the environmental impact

generated by wet-pit mining has not been systematically

assessed. Continued inadequately quantified, managed

and monitored extractions have resulted in substantial

modifications of the coastal zone topography and

ecologic balance. A review of the literature failed to

identify a complete set of criteria that could be

applied to mitigate negative environmental impacts

resulting from wet-pit operations under local

conditions. Very little background data exists about the

impact of this activity on the coastal hydrologic and

ecologic systems in Puerto Rico. The main points of

diverse local studies are mentioned below.

The only field study that focuses on the possible

impacts of sand scraping on ground-water flow was done

by Zack (1983) for a site in Camuy. A battery of

piezometers was installed bordering the Camuy mangrove

to measure hydraulic gradients and salinity

distribution. The author mentions that lowering of the

sand dunes and inland areas altered the overland

drainage to the forest, exposed the water table and

promoted ponding. The study concludes that:

"The removal of sand between the dunes
and the Camuy mangrove probably affects
the mangrove community only insofar as
it has contributed to sand dune degradation.
The effect that extraction has had on
ground-water flow is minimal, and in
itself, would not have been cause for
concern with respect to maintenance of
the mangrove community." (p. 20)

A brief theoretical report on the impact of wet-pit

mining on ground-water was prepared by VAzquez-I@Iigo

(1979). Based on the Ghyben-Herzberg Principle he

concluded that since wet-pit mining is a superficial

operation that does not alter the ground-water level,

the location of the salt water-fresh water interface is

not affected by this type of activity.

Soto (1982) evaluated the conditions of the beach

strip fronting a wet-pit operation in the Afiasco Bay

(the site corresponds to pit *14 in the prepared

inventory discussed later). He concluded that reducing

the buffer zone between the maritime zone (MZ) and the

operation from 50m to 6m would not have an adverse

effect on the shoreline/coastal stability of the studied

segment.

A geologic study that discusses mining

methodology, availability of sand below the water-table

and hydrologic characteristics of the sand to be mined

and the limestone to be used for backfilling at a

particular site was prepared by V61ez (1983) (The site

studied corresponds to pit #9 in the prepared inventory

discussed later). This report constitutes, to the best

of our knowledge, the first serious effort to compile

the necessary technical information on which to base a

sound permit decision. An interesting point made in this

report is that results of a simple comparative test

measuring permeability rates in the limestone and sand,

showed that the in-situ limestone had a high

permeability value that compared favorably with the

sand.

At several potential mining sites test borings

have aided the PR DNR to determine resource availability

below the water-table. Findings (lithology and ground-

water levels) have been included in reports incorporated

in many of the case files.

In view of the need for information on mining

impact and general technical guidelines applying to wet-

pit sand minina iri the coastal zone. the PR DNR

Extraction Committee formally requested on March 14,

1985 that a study be undertaken.

Within this framework, the purpose of this task was

to evaluate wet-pit operations to:

* Produce an island-wide inventory of extraction
sites;

* Characterize abiotic and biotic aspects at
selected mining sites;

* Compile a bibliography of relevant literature;

* Examine the criteria used by PR DNR for
evaluating extraction sites, mining methods and
restoration techniques;

* Produce a preliminary sand mining databank to aid
in the technical decision making process;

* Describe the impacts of wet-pit mining on
coastal hydrologic and ecologic systems; and

* Offer management alternatives to minimize adverse
impacts on the island's coastal zone.

This report documents coastal zone wet-pit sand

mining and examines the impacts of these operations on

ecosystems and ground-water hydrology. Section 2.0

discusses the laws and regulations that apply to wet-pit

mining. Mining processes and resulting impacts are

described in section 3.0. The following two sections,

4.0 and 5.0, describe the methods used in this study,

coastal wet-pit mining history and the criteria used to

choose the sites discussed. General information, mining

history, geology, soils, hydrology, flora and fauna for

each of the monitoring sites is covered in section 6.0

and 7.0. Section 8.0 presents a discussion of mining

impacts on wildlife habitat. The following section 9.0,

lists a summary of findings and conclusions. Resulting

recommendations from this task are included at the

beginning of this report.

2.0 LEGAL ASPECTS

Prior to the creation of the PR DNR, the Puerto

Rico Department of Public Works (PR DPW) regulated

mining operations under the Sand, Gravel and Stone Act,

Law No. 132 of June 25,1968. In 1972, by virtue of Law

No. 23 of June 20, known as Organic Law, of the

Department of Natural Resources, this responsibility was

transferred to the newly created PR DNR. Later ammend-

ments (Law No. 144 of June 3, 1976 and Law No. 54 of

June 27, 1987) further modified Law No. 132.

In October 10, 1977 the Secretary of the PR DNR,

under the authority conferred to him by Article XIX of

Law No. 144, adopted a set of regulations on the

extraction of materials from the Earth's crust. An

ammendment to these regulations was approved on November

24, 1986. The purpose of these regulations is to:

... regulate the granting of permits
for the extraction, excavation,
removing and dredging of the
components of the Earth's crust known
as sand, gravel, stone, earth, silica,
calcite, clay and any other similar
component of the Earth's crust, that
is not regulated as an economic
mineral, in public and private lands,
within the geographical boundaries of
the Commonwealth of Puerto Rico."
(Art. 1, PR DNR, 1978).

Unlike other mining activities, wet-pit mining

involving backfill is not regulated. Specific

provisions are listed only "In the cases where

permission is requested for the excavation, removal or

dredging of materials from the Earth's crust with the
dL
express intention of creating a pond or lake..." (Art.

6, PR DNR, 1978, emphasis ours). The only written

reference authorizing extractions below the ground-water

level implying the need to restore the area by

backfilling and reforestation is through a "Note to the

File" signed by the Earth's Crust Section Director on

March 12, 1981 (Appendix I). This note includes

specific provisions regarding application requirements

and general technical procedures. Consequently, these

procedures have been implemented as an intra-

departmental norm.

The operational criteria for this type of

extraction activity have been stipulated in the mining

permits as Special Conditions and Limitations. They

consist of particular mining methods and restoration

procedures developed gradually through experience.

The extraction permit, signed by the Secretary or

Authorized Person, legally binds the extractor to meet

all the mining provisions (legal and technical) therein

included. The Secretary is empowered to modify, suspend

or revoke the permit if upon his Judgement any of the

permit clauses or provisions of applicable law are

violated, or if the mining operation significantly

altered the local environmental conditions (Art. 16, PR

DNR, 1978).

By 1981 a special clause was being included in all

wet-pit mining permits that stated that such

authorization was subJect to reevaluation once the PR

DNR obtained the necessary data related to the impact of

the mining process on the ecology and hydrology of the

site. Depending on the conclusions reached, the PR DNR

would decide whether to continue or suspend a given

operation.

To guarantee the restoration of the extracted

area, as stipulated in the extraction permit, a

Performance Bond is required for all wet-pit operations.

Although several mining sites have been abandoned

without adequate restoration, as of this date the PR DNR

has not executed a single Bond.

3.0 MINING PROCESSES AND IMPACTS

Process

According to mining procedures currently required

by the PR DNR, sand extraction in the backdune zone and

inland areas begins by using a front-end loader to

remove material in a uniform manner, layer by layer,

over the permitted work area. Using this scraping

technique the maximum depth of operation, if not

otherwise stated, is to 1m above the water-table or mean

sea level (MSL), whichever is higher. The existing top

soil is saved for later spreading during the restoration

process. In most cases extractions must stay 50m away

from the MZ, leaving a buffer zone where material cannot

be mined or deposited. The width of this buffer zone

may vary if a natural or man-made dune line exists,

particularly if it falls within the dimensions

established for remnant dunes (Width=10m, Height=8m,

Slope=IH:lV, Art. 4, Sect. 4.2, PR DNR, 1978), or if a

mangrove forest exists.

Further excavation develops a wet-pit, using a

dragline to remove material from the bottom. Currently,

the pits are allowed to have a maximum surface area of

2,000 M2, preferably following a rectagular shape

measuring 50m by 40m, though often the shape resulting

from mining is irregular and awkward to measure. Pit

depth is usually stipulated as not to exceed 4m.

Excavation pits have to be backfilled with approved

materials at the end of the operation or simultaneously

as the pits are moved within the site. The main criteria

for backfill selection has been that it allow the free

flow of interstitial water at all times. Authorized

backfill material has ranged from limestone, solid

fragments of igneous origin (e.g. granite, andesite,

granodiorite) and/or serpentinite or volcanic sand,

which may be combined with limestone, to a mixture of

limestone and cement dust (with a 1:2 ratio, mixed

previous to deposit). Other material may be presented to

the PR DNR for consideration and approval. Although

there have been pits almost completely backfilled with

topsoil, this is not a desired practice for it signifies

a waste of fertile material that should preferably be

used for surface spreading and ground preparation for

reforestation. In addition, even though illegal,

construction debris and junk has been deposited in wet-

pits, mainly with the idea of reducing the needed volume

of authorized backfill; this lessens the cost of the

backfill process, since adequate material often needs to

be transported from a distant source.

Alternatives for the final elevation of the

rehabilitated site include: (1) the pre-extraction land

levels, (2) a minimum elevation of 1m above the water-

table or MSL, or (3) adjustment to an intermediate

elevation according to site characteristics. Option (1)

has never been fully enforced. The usual practice has

been to leave the sites lower than pre-extraction

elevations, sometimes even below the 1m mark. In all

cases, proper grading is required to allow adequate

surface and subsurface drainage.

Areas potentially available for mining have in the

past been divided into three equal parts and more

recently, into portions of 5 cuerdas (4.85 acres or

19,615 m2). Mining is authorized to begin in one lot at

a time. Once the extraction in the first lot is near

completion and most of the area backfilled, a technical

inspection is conducted to determine if mining can

continue into the adjacent lot. A complete restoration

process consists of: 1) backfilling the wet-pit, 2)

raising land levels, 3) uniformily distributing the

original topsoil over the backfill, and 4) planting the

disturbed area with local vegetation. Often restoration

procedures stop, temporarily or permanently, at one of

these stages.

Impact

Land preparation for mining in the coastal zone

involves the total removal of existing vegetation. The

land surface is often left exposed for months,

representing a period of high vulnerability to surface

erosion. As mining progresses, the backdune and inland

topography become very uneven due to accumulation of

processed and unprocessed material, continued scraping,

and pit development.

Land perturbations due to mining can be

distinguished in the field and from aerial photographs

using the following identification criteria in

comparison to adjacent terrain: (1) sparse and/or absent

vegetation, (2) abrupt topographic changes such as sharp

land cuts, depressions, and remnant uncut land, (3)

signs of erosion and gully development, (4) wet-pits,

(5) water ponding in low terrain, (6) piled material,

(7) inland dune slope failure, and (8)

machinery/processing plant.

The lowering of land levels by mining can increase

flooding probability, particularly in already flood-

prone areas, and may also result in long-term ponding.

With respect to the issue of flooding, the Puerto Rico

Planning Board (PR PB) has confirmed the applicability

of Regulation No. 13 (PR PB, 1972) to mining permits.

The PR PB state (Appendix Il and III):

1) mining in areas identified as
Flood-Zone 1 could be authorized if it
is previously determined that such
activity will not increase flood
levels or velocity of the waters;

2) although normally, wet-pits do
not reduce the hydraulic capacity of
the area, a hydraulic analysis should
be required for each potential mining
site to show that mining will not
alter the surface hydrology, forcing a
reclassification of flood-zone suscep-
tibility.

Some scraping operations have exceeded the maximum

allowable depth, promoting temporary ponding when the

water-table, usually directly controlled by tidal

fluctuations, surfaces or when the high tide enters the

lowlands. A case in point is located to the east of the

urbanization Corales de Hatillo, north of Hwy *2 in the

north coast. Indirectly, sites subject to these

modifications become temporary wet-pits.

Several past sand extraction operations below the

water-table have left open wet-pits. These areas that

were not backfilled have become man-made lakes or ponds.

Their current use varies from recreational purposes, as

the northeast and northwest pits in Loiza (pits *2 and

*3 in the prepared inventory discussed later) to areas

of diverse wildlife sustenance, as in the northwest pit

in Loiza.

4.0 METHODS

4.1 SITE SELECTION

An island-wide inventory of wet-pit extraction

sites was prepared by means of a permit file search

(Permits Office, PR DNR), conversations with past Permit

Office directors and current employees, aerial

photograph evaluations and field inspections of sites to

verify information. From this pool of data the criteria

to determine the type of study to be conducted for each

site were formulated. Three sites were selected for

detailed analysis and four for analysis of fauna and/or

flora only. The remaining thirteen pits listed were

subject only to the preliminary file inspection to

determine applicability.

4.2 COMPLETE MONITORING SITES

Three sites representing different coastal

ecological zones at different stages of the wet-pit

mining process were chosen for detailed study. Pertinent

permit files were thoroughly reviewed to become familiar

with the peculiarities of each operation and to outline

the site's mining history. Twelve field visits were

made to each site between July 1987 and March 1988 for

data collection. Surface photographs were taken to

document site conditions.

Changes in land use and floristic composition were

determined from aerial photographs corresponding to

1963, 1964, 1971, 1977, 1978, 1986 and 1987 at a scale

of 1:20,000. Vegetation maps were prepared using some of

these photographs to show the changes observed for each

site before, during and after mining operations. The

existing flora present in the extracted and undisturbed

nearby areas was compared by means of vegetation

profiles.

The biological study was limited to the most

conspicuous macrofauna, vertebrate and invertebrate

species found in both disturbed and undisturbed nearby

areas. Bird count censuses were conducted by foot at

dawn and dusk along predetermined transects. Field

sightings were recorded to structure a species list for

mammals, reptiles, amphibians, birds and crustaceans.

The United States Geological Survey, Water

Resources Division (USGS WRD), conducted a hydrologic

investigation of these sites to determine lithology,

water quality, water levels, flow patterns and hydraulic

properties of the shallow coastal aquifers. A total of

sixteen test wells were drilled to depths ranging from

8.5ft (2.6m) to 37ft (11.3m); at least one well per

site was installed near the open wet-pit and another in

an undisturbed zone which served as control (according

to site conditions at that time). The wells were

monitored for changes in water levels and water quality

from August to December 1987. Hydraulic tests (slug-

injection) were completed in September 1987 to determine

the hydraulic conductivity at each well site. Bathymetry

and conductivity profiles were prepared for two of these

wet-pits.

Site geology, soils, and susceptibility to flooding

and the storm wave swash were described for each site

using existing maps, field data and interpretation of

drilling cores.

4.3 PARTIAL MONITORING SITES

Existing flora and/or fauna and land use were

described for four open wet-pits, three of them in the

same locality. Experimental fishing was done in one

abandoned lake by members of the Marine Section,

Scientific Investigation Area, PR DNR. Fish were sampled

using a 275ft (83.82m) experimental gill net and a 50ft

(15.24m) bag seine, kept in the water for 10.54 hrs.

Three nets were located in the north part of the open-

pit and three in the south. Captured fish were

identified, measured, and weight. Three fishermen and

residents were interviewed for fishing information.

4.3 LITERATURE SEARCH

Information related to wet-pit mining was requested

from selected agencies and organizations both locally

and outside Puerto Rico. A literature search was

conducted through the Dialog Information Service via the

University of Puerto Rico. All literature and documents

received were analyzed and included in a bibliography

list.

5.0. ISLAND-WIDE INVENTORY

Twenty open pit mining operations below the water-

table, at various stages of development, were identified

within the limits of the coastal zone. These have been

geographically located and coded as described in Figure

2. Twelve operations (60%) have left abandoned open

pits; three pits (15%) were backfilled; and five (25%)

are active wet-pit operations (Table 1).

Prior to the establishment of the PR DNR in 1972,

four operations of this type were authorized by the PR

DPW in the municipality of Loiza. The sites have been

identified in the field since the pits were left open

and are clearly visible due to their size. They have

been listed in the prepared inventory as pit numbers

2,3,4, and 5 (Table 1). Evidence of earlier extractions

of this type were not found.

Towards the end of the 1970s the PR DNR began to

authorize extractions below the water-table. During

this time three permits were granted, distributed in

three municipalities: Mayaguez, Loiza and Ponce (Carlos

Santana and Leovigildo VAzquez, former directors of the

Permits Office, pers. comm.). Because the Loiza pit is

still open, its location was pinpointed using the 1977

FIG.2. INVENTORY MAP OF EXTRACTION SITES

A T L A N T I C 0 C. E A N

CAMUY
10-0 9.0 SANJUAN

%
%

%
[3 AGUADA 6-A
R I N C 0 N P I T NUMBER S I T E C 0 D I-N G 2.3
12-6
ANASCO 1-20 ABANDONED OPEN PIT
0 ACTIVE OPEN PIT
14- is- A MAYAGUEZ o FILLED PIT

17-0

GUAYANILLA PONCE 19-0
18-0- o

C A R I B B E A N S E A
20- 13
0 0, 0 0

1
18.0

TABLE 1 - LIST OF INVENTORY SITES AND WET-PIT STATUS CODE

PIT NUMBER LOCATION SELECTION CRITERIA(**) TYPE OF STUDY

1A RIO GRANDE FILE

2& LOIZA I.LOCATION (NORTH- FLORA,
(NORTH-EAST PIT) EAST COAST) FAUNA AND
2.ABANDONED OPEN PIT USES
FOR APPROX. 20 YEARS FILE NOT
3.ADJACENT TO REMNANT DUNE AVAILABLE
4.EXTREMELY LARGE AREA
5.RECREATIONAL USE

3L LOIZA 1.CURRENTLY BEING USED FLORA,
(NORTH-WEST PIT) FOR RECREATIONAL PUR- FAUNA AND
POSES USES
2.WILDLIFE HABITAT FILE NOT
(ENDANGERED AND PROTEC- AVAILABLE
TED SPECIES OBSERVED)

416 LOIZA FLORA
(SOUTH PIT) FILE NOT
AVAILABLE

5A LOIZA FILE NOT
(MOST SOUTHERN PIT) AVAILABLE

6,& LOIZA FILE NOT
(PIT SOUTH OF LOIZA AVAILABLE
WASTE TREATMENT PLANT)

TABLE 1 (CONT.)

PIT NUMBER LOCATION SELECTION CRITERIA(**) TYPE OF STUDY

7A CAMUY 1.LOCATION (NORTH COAST) DETAILED
(EAST PIT) 2.ABANDONED OPEN PIT
3.FILLED PIT
4.TYPE OF BACKFILL MATERIAL
(CRUSHED LIMESTONE)
5.ADJACENT TO UNMINED AREA,
PROVIDING A POSSIBLE CON-
TROL SITE

8A CAMUY FLORA
(WEST PIT)

90 AGUADA 1.LOCATION (WEST COAST) DETAILED
2.ACTIVE OPEN PIT BEING
BACKFILLED
3.TYPE OF BACK FILL MATE-
RIAL (LIMESTONE)
4.UNMINED AREAS PROVIDING
DETAILED COMPARISON IN-
FORMATION

loo RINCON FILE

119 ANASCO FILE

12,& ANASCO FILE

139 ANASCO FILE

14,& ANASCO FILE

156 ANASCO FILE

TABLE 1 (CONT.)

PIT NUMBER LOCATION SELECTION CRITERIA(**) TYPE OF STUDY

160 PONCE 1.LOCATION (SOUTH COAST) DETAILED
2.ACTIVE OPEN PIT WITH
BACKFILL IN PROGRESS
3.TYPE OF BACKFILL MATE-
RIAL (CRUSHED SERPEN-
TINITE AND LIMESTONE,
CEMENT POWDER, CONS-
TRUCTION DEBRIS, SOLID
GARBAGE, JUNK)
4.ADJACENT TO SEA, MAN-
GROVE AND SALT FLATS
5.EXTRACTION AND PROCES-
SING SITE IN WETLAND
AREA

170 PONCE FILE

180 PONCE FILE

190 PONCE FILE

20,& GUAYANILLA FILE NOT
AVAILABLE

STATUS CODES: & Abandoned Wet-Pit (Open)

0 Active Wet-Pit

Filled Pit

APPLIES TO SITES SELECTED FOR INDIVIDUAL MONITORING

SEE APPENDIX IV

aerial photograph and corroborated to exist within the

limits of the coastal zone. This pit has been identified

as pit #6 in the prepared inventory. Case files for the

Mayaguez and Ponce operations were not found to verify

their exact locations or if they occurred within the

coastal zone limits. Therefore, they were not included

in the prepared inventory.

In the decade of the 1980s there was an increased

interest in mining the sand deposits available below the

water-table. Twelve (60%) of the extractions identified

in this study were granted during this decade (Table

21). Mining operations have concentrated in the

northwest coast, which could be explained by the

following reasons:

Geology: The best sand deposits for construction
purposes are of non-organic terrigenous origin; these
have been widely distributed along the north-northwest
coast. The deposits on the south are more saline and
have a higher content of organic matter, making them
less suitable for construction purposes.

Extractor: Most of the extractors that mined the
island's surface sand deposits (e.g. dunes and inland
areas) were located in the northwest area. Once these
reserves were depleted, many extractors invested in the
development of subsurface deposits.

Development: Many of the subsurface sand deposits
that could have been exploited are no longer accessible
due to the urban expansion. In other areas, private
land owners have shown greater interest in urban
developments rather than mining.

TABLE 2 FIRST PERMIT DATE AUTHORIZING WET-PIT EXTRACTION

PIT NUMBER FIRST PERMIT DATE

1 1983

2 *DECADE OF 1960

3 of

4 it

5 tf

6 *BETWEEN 1972-77

7 1979

8 1981

9 1983

10 1985

11 1983

12 1982

13 1983

14 1982

15 1981

16 1978

17 1987

18 1987

19 1987

20 *DECADE OF 1970

File not available

The three cases selected for detailed study, as

outlined in Appendix IV, correspond to pit numbers: 7

(Camuy), 9 (Aguada) and 16 (Ponce) (Figure 3).

Selection criteria was based on geographical location,

operational status, type of backfill material used, size

of mining area, existence of ecologically important

systems in or nearby the extraction site representative

of each area and proximity of unmined areas providing

comparative information (Table 1).

Land uses, flora and/or fauna were outlined for

pits #2,3 and 4 in Loiza. Vegetation changes are

illustrated for pit *8 in Camuy. The selection

criteria for these pits are described in Table 1. A

study file of each of the remaining pits was prepared to

obtain relevant permit information.

67'00' 66,30, 6600c),

18*30' y SAN JUAN

AGU DA

leoc), -PONCE

0 10 20 30 KILOIY
SAND EXTRACTION AREA f I I - - I
0 10 20

FIG.3- LOCATION OF SAND EXTRACTION SITES

6.0 COMPLETE MONITORING SITES

6.1 CAMUY

6.1.1 GENERAL INFORMATION

MUNICIPALITY: Camuy PR DNR REGION: Arecibo

TOPOGRAPHIC MAP: Camuy Quadrangle SITE ACCESS: Road PR-485,
(Fig. 4) Km. 2.2, Bo. Membrillo

PIT NUMBER: 7 (Photo 1a) PIT CODE: A Abandoned
Open Pit

APPROX. EXTRACTED AREA AVERAGE DISTANCE FROM:
66, 793 m@4 MZ (*): 80 m
(17 cuerdas)

APPROX. SIZE OF PIT PIT DEPTH:
1,964 m2 Max.: N/A
(0.5 cuerdas) Min.: N/A

TYPE OF BACKFILL: Limestone, sand,
topsoil

RESTORATION STAGE: Incomplete backfill ECOSYSTEMS:
Natural succession
revegetation Pre-mining: Hay fields,
Coconut groves

Post-mining: Seasonal
marsh, herbaceous swamp,
coastal thicket

FLOODING SUSCEPTIBILITY (m*): None

STORM WAVE SWASH: Not available

Source: January 1987 aerial photograph
Source: FEMA (1978)

6.1.2 MINING HISTORY

The date that extraction began is unknown, but

file records indicate that by 1977 this area was being

scraped. Towards the end of 1978 land levels were below

that of PR-485 (access road), the water-table had been

reached, and ponding was evident. In January 1979

mining was authorized to extend 3m below the water-table

with a maximum wet-pit area of 25m by 25m. A 10m buffer

zone was required from the axis of PR-485. The type of

backfill material to be used and the final land

elevations were not specified in the permit.

A January 1986 file report indicates that the area

had been backfilled only up to the water-table, leaving

a depression that to the south and north of PR-485 was

about 6m and 3m, respectively, below its elevation. The

preocupation of possible permanent ponding was brought

to the attention of the Permit's Office.

In February 1980 a new permit was issued for a

contiguous area to the south of PR-485- This permit did

not authorize mining below the water-table and the

extraction area was not allowed to be larger than 60m by

40m. This area was to be backfilled to land levels

existing prior to this permit, calculated to average

2.Om above MSL. During the rest of this year several

file reports mention that the area being extracted

exceeded that authorized by the permit and that, in

addition, restoration had not begun. On February 1981

the Department authorized mining to 3m below the water-

table in this area; the pit area and backfill require-

ments stayed as previously described.

Later file reports indicate that backfill material

was obtained from the limestone hills found to the south

of the extracted site. Although, a large portion of the

mined area had been restored, a wet-pit remained open.

A new permit sustaining the authorization to mine

3m below the water-table was issued on August 1981. The

wet-pit surface area was not to exceed 900m2. The type

of backfill to be used continued not to be specified.

It was not until a permit signed in February 1983 that a

backfill clause was included specifying possible fill

material.

By September-November 1982 mining had ceased but

the wet-pit remained open, measuring 30m by 40m.

Salinity tests in the pits suggested saline conditions.

In October 1983 mining was resumed; the allowable pit

area was increased to 1,800 M2. A July 1984 file report

indicates that the open pit had a surface area of 2,050

M2. On June 1985, based on recommendations emmitted by

the Extraction Committee in May 1985, an additional

permit was denied based on failure to appear at hearings

held in the PR DNR to review permit violations. Since

that date no mining has taken place. Currently, there.

exists an open pit in the east section of the site; the

restored extraction area (to the west of the open pit

and south of PR-485) is about 5 to 6 meters below the

access road, PR-485.

6.1.3 GEOLOGY AND SOILS

According to Monroe (1963) the sand deposits mined

in this site correspond to the Blanket sand deposits

(Qbs) of Quaternary (Pleistocene) age that overlay the

Camuy Formation (Fig. 5). This deposit consists of fine

to coarse ferruginuous quartz sand; some of the material

may be residual and slightly reworked sand derived from

the upper member of the Camuy Fm. and from eolianite;

some may have been blown inland from the beaches and

recent dunes.

The limestone fill was obtained from the nearby

hills identified as the Upper member of the Camuy

Formation (Tcu) of Tertiary (Miocene) age (Monroe,

1963). This member is described to consist of chalk,

sandy chalk, sandy limestone, sandstone, and very fine

grained, powdery dolomite. Only the non-sandy parts of

the member outcrop in the site quarry; it consists of

white to orange chalk and limestone with abundant

fossils; also, contains very finely cristalline, powdery

limestone (Fig. 5).

The Soil Conservation Service (1982) has defined

the following soil units found in the mined area (Fig.

TP- Tropopsamments, hummocky. Deep, sloping,

excessively drained sandy soils on ridges and small

hills along the coast. These soils have very rapid

permeability, and very low available water

capacity. Runoff is very slow and the level of

natural fertility is very low. Reaction is mildly

alkaline to moderately alkaline throughout. Some

areas of the unit are suitable as a source of sand

for construction. Generally unsuited for farming.

RIC- Rio Lajas sand. Deep, gently sloping to

sloping, somewhat excessively drained. It is in

small valleys and on undulating hills on the

coastal plains. Permeability of this soil is

rapid, and the available water capacity is very

low. Runoff is slow to medium. Natural fertility

is low. Good roadfill, contains significant

35
_04

amounts of sand. Good topsoil. This soil is well

suited for such pasture plants as stargrass,

pangolagrass, and merkergrass. Mainly used for

sweet potatoes, cassavas, and pigeon peas. Some

small areas are in coconuts and tobacco. Crops on

this soil respond to fertilizer applications.

6.1.4 HYDROLOGY

Six test wells were drilled in this site to gather

lithologic, water quality, and water-level data. II slug"

injection tests were performed in all wells to determine

relative hydraulic conductivities and/or transmis-

sivities of the site. Well distribution, methodology,

results of tests and well monitoring are described and

summarized in tables and figures in Appendix V.

Test wells number 6, 7, 9, and 10 were drilled in

backfilled areas. Test well number 11 was installed in

an unmined area.

',I,
wo

6.1.5 FLORA

In 1963, prior to the begining of mining, most of

the upland site was dedicated to agriculture (hay

fields) (Fig. 6, 7c). Other existing vegetation

consisted of coconut palm groves located along the north

end of the study site between Road PR-485 and cultivated

lands (Fig. 6). These areas were later subjected to

mining;

A semi-evergreen seasonal forest, located on the

nearby limestone hills, was disturbed by mining. The

extracted material was used for partial backfill of the

areas subject to sand extraction.

The aerial photo of January 1977 showed changes in

cover distribution and plant associations due to sand

scraping operations (Fig. 6). Sparse pioneer vegetation

covered the extraction area, surrounded by a coastal

thicket association (Fig. 6, 7a, 7b). This vegetation

replaced part of the coconut groves and the hay

monoculture that existed in 1963.

Between 1977 and 1987 considerable changes occurred

in the study site and nearby areas (Fig. 6). The aerial

photo of 1987 indicated the existence of four distinct

community types corresponding to site topography and

hydrologic zones: Open water (abandoned open pits; photo

1b), seasonal marsh (photo 1c), coastal thicket (photo

Ilk
W ld,le), and herbaceous swamp (photo 1f). In addition,

the aerial photo showed two barren land sections: one of

them was an area corresponding to a filled wet-pit and

the other to a limestone quarry. Findings from several

surveys conducted during July 1987, February and March

1988, indicate that these conditions still exist.

CAMUY: PLANT SPECIES ADJACENT TO THE MINING AREA

I. Sand dune vegetation

Achryranthese aspera var. aspera

Bidens pilosa Mariscus peduticulatus

Canavalia maritima Remirea maritima

Chamaesyce buxifolia Scveola plumieri

Coccoloba uvifera SRartina patens

Ipomoea pes-caprae Sporobolus virginicus

I. stolonifera Trephrosia cinerea

Wedelia trilobata

II. Monoculture

Panicum sp.

CAMUY: PLANT SPECIES IN THE MINING AREA

I. Seasonal Marsh

Aeschynomene sensitiva Lippia nodiflora

Cyperus liguralis Sesbania sericea

11. Coastal thicket

AeschynoiRene sensitiva Ludwi-gia octovalvis

Bidens alba Mimosa pudica

Canavalia maritima Neptunia plena

Chamaesyce orbifolia Pavonia spicata

Commelina diffusa Pennicetum purpureum

Cyperus ligularis Sesbania sericea

Ipomoea pes-caprae Stachytarpheta Jamaicensis

Leucaena pallida Thunbergia alata

LiRPia nodiflora

III. Herbaceous swamp

Typha dominguensis

6.1.6 FAUNA

Sixteen species representing four animal groups

were recorded for this site during July 1987 and January

1988.

Amphibians, reptiles and mammals were found

throughout the extracted site. Bird use of this site

was limited to roosting and probably feeding. Only one

avian species (common gallinule) used the wet-pit for

nesting. Two chicks of this species and one adult were

observed during the survey.

CAMUY: FAUNA OBSERVED

Amphibia

Bufo marinus

Leptodactylus albilabris

Reptilia

Ameiva exsul

Anolis Pulchellus

Aves

Coereba flaveola Mimus poliglottos

Columbina passerina Myiarchus antillarum

Falco sparverius (Endemic)

Gallinula chloropus Petrochelidon fulva

Quiscalus niger

Mammalia

Herpestes auropuntatus

Mus musculus

Rattus.norvegicus

R. rattus

A T L A N T I C 0 c E A N

Peh6n de Afuera
@-j Pta PeA6n

Pta Puntilla

R
L3 go 01 1

B I

C A M U Y
SAN JUAN

MAYAG-6EZ

FIG.4. LOCATION OF CAMU-Y SITE (PIT NO- 7)
(U.S.G.S. 1972.)

A T L A N T I C 0 C E A N

TP
HD
<9 R Ic
RSF

CY CIE 2 RIC
SgD 9DO-
Ve EbC SgD
Amc GeC
EbB CID2 S9

Sol L MAP OF CAMU.Y SITE (PIT No. 7)

A T L A N T f C 0 C E A N
Qe
'@@Qe-
Od
t d
Qe QS- Qbs Ge QS

Q (ae
Tcu 6e

GEOLOGIC MAP OF CAMU.Y SITE (PIT NO. 7)

FIG.5. SOIL AND GEOLOGIC MAPS OF CAMUY SITE.
(S.C.S.1982; Monroe, W.H. 1963.)
(Key to symbols: Appendix VI)

FIG. 6. V E G E T A T 1 0 N M A P 0 F C A M U Y S I T E

...........

MIN

-OZA-

wzw

...... ....

old- *PC.

c C.

Ell_
0 ... "41k.T.16
..'e. USPA4SC PIGNtCA VC-CT-"--
tUNtICKFILL90 aXT.ICTI.- 1-911

t I

FIG. 7. CROSS SECTION ILLUSTRATING CHANGES IN PLANT ASSOCIATION AT CAMUY

HERBACEOUS
SWAMP

ROAD PR-115

SCRAPING
HAY ORIGINAL COASTAL THICKET- SEASONAL MARSH AND
MONOCULTURE LEVEL BACKFILL

SCRAPING AND EXTRACTION 0 E L 0 W
WATER TABLE (PARTIALLY SACKFILLED)

HAY HERBACEOUS COASTAL HERBACEOUS
MONOCULTURE I_COASTAL_l
SWAM P THICKET SWAMP THICKET

OAD PR-115

SCRAPIN G
ABANDONED AND
OPEN PIT BACKF(LLEO

SCRAPING AND EXTRACTION BELOW
WATER TABLE (PARTIALLY BACKFILLED)

ROAD PR-tt5 ACTIN
DUN

SCRAPING AND
MAY MONOCULTURE BACKFILLED
S AZ"r

Photo la Camuy site (Pit #7). Panoramic view
towards the northwest. Abandoned wet-pit
is seen in the background, to the right.

91h

-A .. des-
loft*

79"""W" "I

PhotDlb Partial view towards the southeast.
Abandoned wet-pit found in the northeast
portion of the site; a herbaceous swamp
surrounds the wet-pit.

Photo lc Partial view towards the northwest.
Seasonal marsh developed in part of
the extracted area. Access Road PR-485
is located on top of higher terrain seen
in the background.

Photo ld Partial view towards the southwest.
Coastal thicket and herbaceous swamp
developed in part of the extracted area.

Photo le Partial view towards the northeast
Coastal thicket developed in part of
extracted area.

Photo lf Partial view towards the southeast.
In the foreground, a herbaceous swamp
developed next to the abandoned wet-pit.

6.2 AGUADA

6.2.1 GENERAL INFORMAT10N

MUNICIPALITY: Aguada PR DNR REGION: Aguadilla

TOPOGRAPHIC MAP: Aguadilla Quadrangle SITE ACCESS: Road PR-115,
(Fig. 8) Km. 17.0, Bo. Rio Grande

PIT NUMBER: 9 (Photo 2a) PIT CODE: 0 Active
Open Pit

APPROX. EXTRACTED AREA AVERAGE DISTANCE FROM:
141,444m2 MZ (*) : 200M
(36 cuerdas) Rio Grande de Aouada: 20m

APPROX. SIZE OF PIT PIT DEPTH
7,858m@' Max.: 2.3m
(2 cuerdas) Min.: 1.6m.

TYPE OF BACKF1LL: Limestone

RESTORATION STAGE: In process ECOSYSTEMS AND USES:

Pre-mining: Sand dune
vegetation, palm grove

Transitional: Sparse pioneer
vegetation, open water

Post-mining: Barren land

FLOODING SUSCEPTIBILITY
Within the 100YR floodplain

STORM WAVE SWASH: Not Documented

Source: January 21, 1987 aerial photograph
Source: Field measurements (not adjusted to MSL)(Appendix
V, Figure 22)
Source: FEMA (1982)

6.2.2 MINING H1STORY

As mentioned earlier, V61ez (1983) discussed in a

preliminary geologic study the mining metholody,

availability of sand below the water-table and

hydrologic characteristics of the sand and limestone to

be used for backfilling in this area. This information

served as a useful tool during the permit evaluation

period.

On May 1984 a three year permit was signed that

included specific clauses for sand and limestone mining;

the latter to be obtained from hills to the southeast of

the sand extraction site. Among the required clauses,

the extraction was to keep a 50m buffer zone from the

Rio Grande, to the west, and a 20m distance from the MZ,

to the northwest. The wet-pit surface area was not to

exceed goo M2f with a 2m depth. At this time, the

restoration process required backfilling with limestone

up to levels existing prior to the beginning of mining,

an average of 4.Om above MSL.

An October 1984 file report indicates that the wet-

pit was being backfilled with topsoil. In addition to

this, during the following months the extraction

extended beyond the first lot of 5 cuerdas authorized,

without properly restoring the mined site and also, the

pit exceeded the authorized size.

In response to an April 1985 permit ammendment

requested by the extractor, in May 1985 the Department

authorized an increase in pit size to 1950 m2. The

backfilling procedure was to consist of depositing

limestone up to 2m above the water-table followed by 2m

of top soil to define the topography that existed prior

to mining.

Subsequent file reports indicate that the extractor

continued to violate the permit clauses, particularly by

not backfilling the extracted site to 4m above MSL and

by not limiting the wet-pit size. After several

communications between the PR DNR and the extractor and

as a result of a PR DNR decision through the Extraction

Committee, on April 1986 the permit clauses were

oficially modified. Consequently, backfilling with

limestone was approved to reach only 1.5m above the

water-table followed by 0.5m of topsoil to reach the

minimum permissible final land elevation of 2m. above the

water-table.

On October 1987 the extraction permit was renewed

for one year. The buffer zone between the extraction and

the MZ was reduced to 10m. This permit requires the

extractor to rebuild with sand part of the existing dune

to comply with the minimum residual dune dimensions. The

final land restoration level was maintained at 2m above

the MSL, with adequate inclination to provide good

surface flow and minimize ponding. Mining is active at

this time and progressing towards the easternmost

section of the site.

6.2.3 GEOLOGY AND SOILS

The sand deposits mined in this site have been

identified as Beach deposits (Qb) of Recent age (Monroe,

1969) (Fig. 9). They are described to consist of quartz

sand, shell fragments, and scattered grains of other

minerals resistant to weathering; cementation to

beachrock is common; deposits inland from present

shoreline are covered by a thin blanket of sand blown

from present beaches and dunes; gently crossbedded,

generally dipping toward the sea (0-5m thick).

The fill material for this site is obtained

exclusively from the limestone hills to the south,

identified as Cibao Formation (Tc). This unit is of

Tertiary age (Oligocene-Miocene). In Monroe (1969) this

formation was described as follows: Interbedded

calcareous clay, soft earthy chalk, and hard very fine-

grained calcarenite and soft nongranular limestone.

Commonly fossiliferous. In areas near Aguada, the base

of the formation contains irregularly bedded medium-

grained calcarenite locally resting on a few meters of

sandy gravel.

The Soil Conservation Service (1975) has defined

the following units in the mined area (Fig. 9):

Cd- Catafio sand. Deep, nearly level calcareous

soils occurring as strips along the coast in areas

close to sea level, but above high tide.

Permeability is rapid, the available water capacity

is low, and fertility is low. They formed in sandy

material consisting of shell fragments, quartz

grains, and subrounded fragments of volcanic rock

(loose, nonsticky and non plastic sand). Good

roadfill. Poor topsoil. This soil is not suited

for cultivated crops. Its use is limited mainly to

pasture, coconuts, or wildlife habitat.

6.2.4 HYDROLOGY

Five test wells were drilled in this site to gather

lithologic, water quality, and water-level data. ftslugfl

injection tests were performed in all wells to determine

relative hydraulic conductivities and/or transmis-

sivities of the site. Well distribution, methodology,

results of tests and well monitoring are described and

summarized in tables and figures in Appendix V.

Test wells were installed in the following areas:

numbers 12, 13, and 14 in backfill; number 15 in an

unmined sand site; and number 16 in the limestone fill

deposit.

6.2.5 FLORA

Site vegetation prior to the begining of mining

behind the backdune area was an upland type consisting

of a coconut palm canopy with a weedy herbaceous

understory (Fig. 10, 11). This former upland was the

center of mining operations for this site (Photo 2b).

Figures 10, 11a, and 11b illustrate the changes in
0 vegetation due to mining, Pioneer vegetation covered the

backfilled areas as wet-pit development advanced (Photo

2c), although a great portion of the backfill is still
0 unvegetated (Photo 2d).

The sand dune was covered with dense shrubs,
0 grasses, and sparse palms (Fig. 11). This system was

partially altered when the backdune area was scraped and

later capped with top soil removed from the adjacent

extraction site (Fig. 11a)(Photos 2e, 2f, 2g).

The other system impacted by mining in this

locality was a semi-evergreen seasonal forest, found on

the nearby limestone hills (source of the backfill

material). As long as sand extraction continues, this

deposit will be mined for backfill and the plant

association affected.

Other plant associations surrounding the extraction

site have remained in unaltered conditions. To the

south, there exists a wide area dedicated to sugar cane

production. To the west, the river bank is

characterized by typical riverine vegetation (giant

grasses).

The mining operation is moving to the east, where

remnants of the upland plant associations existing prior

to mining are found (Photos 2h, 2i).

AGUADA: PLANT SPECIES ADJACENT TO THE MINING AREA

I Sand dune vegetation

Coccoloba uvifera Ipomoea pes-caprae

Cocos nucifera Spartina patens

Hymenocallis caribaea Widelia trilobata

11 Palm grove with littoral herbaceous understory

Coccoloba uvifera Terminalia catappa

Cocos nucifera Spartina patens

Ipomoea pes-caprae

AGUADA: PLANT SPECIES IN THE MINING AREA

Pioneer successional vegetation over backfill

Canavalia maritima Ipomoea pes-caprae

Catharanthus roseus I. trilobata

Chloris inflata Mimosa pudica

Crotalaria sp. Panicum sp.

Cyperus ligularis Sida sp.

Euphorbia cyathaphora Stachytarpheta jamaicensis

Fimbristylis cymosa Vigna repens

Wedelia trilobata

6.2.6 FAUNA

A total of eight species representing three

families were recorded during July 1987 and March 1988,

which included the following: crustaceans (1 sp.),

reptiles (2 sp.)l and birds (5 sp.). Fregata

magnificens is included in the Watch List of the Puerto

Rico Natural Heritage Program (PR NHP) and Pelecanus

occidentalis is listed as an endangered species by

Federal and State laws.

Several borrows of ghost crab were found adjacent

to the extraction site in a palm grove area. Pioneer

vegetation was an important feeding habitat for Zenaida

Dove and finches. The close proximity of the Rio Grande

River explains the presence of estuarine-marine avifauna

like the frigate and brown pelican, which used the river

for feeding.

No fauna was recorded in the active mining

operation area.

AGUADA: FAUNA OBSERVED

Crustacea

Ocypodes sp.

Reptilia

Anolis cristatellus

A. pulchellus

Aves

Fregata magnificens (PR NHP Watch List)

4w Lonchura punctulata

Pelecanus occidentalis (Endangered)

Progne dominicensis

Zenaida aurita

MONA PASSAGE

FIG.8. LOCATION OF AGUADA SITE (PIT NO.9)
(U.S.G.S. 1960.)

MONA PASSAGE

Cd Es
Cd Cd
MOB
Sn Sn//-\
d Ma a lu Nod
S@ 11 6 CfE

SOI L MAP OF AGUADA S I T E(PIT NO.9)

M 0 N A PASSAGE

5
Ob

Ob 0
Ob
Ic 00
Ob Qa Tc Tc @ P@lr'c\-l

GEOLOGIC MAP OF AGUADA SITE (PIT NO.9)
-0
FIG.9. SOIL AND GEOLOGIC MAPS OF AGUADA SITE.
M FON A P A S

(S.C.S. 1975; Monroe, W.H. 1969)
(Key to symbols: Appendix VI)

FIG. 10. V E G E T A T 1 0 N M A P 0 F A G U A D A S I T E

... . . . . . . . . . . . . . . . .

. ...................

......... ...........
............

.............

.............................
.....................

. . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . .
. . . . . . . . . . . . .

E3C 0 A S T T H I C K E T

SJJGAR CANE

SEMI- EVERGREEN SEASONAL FOREST
EIPALM GROVE
E]SAND DUNE VEGE TATION

SANDY BEACH
SOURCE: AERIAL PHOTO 19TO ERIVERINE V E 0 E T A T 1 0 N

............

. . . . . . . . . . .
USCRAPING AREA
EJCOAST T H I C K E T
. . . . . . . . . . . . . .
. . . . . . . . . . . .
99OPEN PIT

SAND DUNE VEG E TATION
0SUGAR C A N E

P A L #4 0 R 0 V E
El S A N D Y 8 E A C H
m LIMESTON OUARRY
N MRIVERINE VEGETATION

0 500

METERS

'COURCE: AFWIAL P-40TO 19MI

FIG.11. CROSS SECTION ILLUSTRATING CHANGES IN PLANT ASSOCIATION AT AGUA

S C R A PING TOP
OVE

SAND
8 A R R E N L A N D DUN E

HARVESTED ADDITIONAL BACKFILL COVERED WITH
SUGAR CANE----@- Top SOIL (FINAL RES TORATI DIN LEVEL )-I
FIELD

SPARSE PIONEER
V E G E TA Tj 0 N

SAND DUNE
SUGAR CANE SCRAPING AND EXTRACTION SCRAPING
FIELD BELOW WATER TABLE (BACXFILLED) S
OPEN PIT

AND DUNE SANDY
SUGAR 'CANE DIRT ROAD P A L MGROVE WITH LITTORAL BEACH
F I E L 0 HERBACEOUS UNDESTORY

Photo 2a Aguada site (Pit #9). Panoramic view
towards the north.

.1&
4W

dkk
4W

d1h
W,

Mh
OF

Photo 2b - Partial view towards the north.
Upland subject to mining.
0

ALL

Photo 2c Partial view towards the northeast.
Sparce pioneer vegetation growing on
top soil spread over limestone fill.
The duneline can be seen in the background.
A&-

Photo 2d Partial view towards the east.
Unvegetated area that has been back-
filled with limestone and a topsoil
layer. The coconut palm groves in the
background define the unmined section.

@419WI

Photo 2e Partial view towards the east.
Scraped backdune.

xv@
pj

A.-7

Photo 2f Partial view towards the east. Dune
capped with top soil;remnant upland
palm grove is seen in the background.
\\@nq

14M

A 4.

photo 2g Close-up of dune vegetation being
covered with top sOil-

imk%wm 1! 01,

Photo 2h Partial view towards the north. Active
wet-pit found in the eastern portion of
the site. The duneline is seen in the
background.

aw,

Photo 2i Partial view towards the north.
To the left, a sand scraped section,
in the foreground, a remnant upland
subject to mining.

6.3 PONCE

6.3.1 GENERAL INFORMATION

MUNICIPALITY: Ponce PR DNR REGION: Ponce

TOPOGRAPHIC MAP: Pta. Cuchara SITE ACCESS: Road PR-2,
Quadrangle Km. 256.8, Bo. Canas
(Fig. 12)

PIT NUMBER: 16 (Photo 3a) PIT CODE: 0 Active
Open Pit

APPROX. EXTRACTED AREA(*): AVERAGE DISTANCE FROM:
125,728m2 MTZ (*): 150m
(32 cuerdas) Mangrove Forest: Om

APPROX. SIZE OF PIT PIT DEPTH
7,858m2 Max.: 2.2m
(2 cuerdas.) Min.: 1.6m

TYPE OF BACKFILL: Limestone,
cement dust, const. debris, junk

RESTORATION STAGE: In progress ECOSYSTEMS AND USES:

Pre-mining: Deciduous
seasonal forest,
seasonal marsh,
mangrove swamp

Post-mining: Young
thorn scrub, salt flat,
open water, barren land

FLOODING SUSCEPTIBILITY
Within the 100YR floodplain

STORM WAVE SWASH: Not documented

Source: January 2, 1987 aerial photograph
Source: Field measurements (Adjusted to MSL)
(Appendix V, Figure 21)
Source: FEMA (1981a)

6.3.2 MINING HISTORY

Mining in this area began before October 1977. A

file report indicates that the extraction site was

covered by approximately 1m of water and that the pits

had been partially backfilled with junk. A February 1977

file report indicates that extractions previous to 1971

created wet-pits that were backfilled with construction

debris and junk.

In April 1978 mining depth was authorized to reach

50ft (15.24m) at a maximum sand extraction rate of

1,OOOM3 daily. The maximum wet-pit size authorized was

25 by 50m (125OM2). The type of backfill material to be

used was not specified.

This permit was renewed in September 1979. The

extractor continued to backfill with solid construction

debris and limestone. By November 1980 most of the land

east and south of the extraction site had been

backfilled and covered with vegetation. Nevertheless, a

ponded area measuring 10 by 15m (approx.) existed to the

southwest of the wet-pit.

In November 1980 a three year permit authorizing a

wet-pit depth of 5m was issued; the pit size required

continued to be 50 by 25m. The type of backfill and

final land levels were still.not specified. In August

1983 the extractors requested to backfill with a mixture

of cement dust and limestone at a 2:1 ratio as

authorized at another extraction site (pit *18). This

was approved by the PR DNR on September 1983. A

November 1983 file report indicates that the pit

measured over 8,5OOm2 with an approximate maximum depth

between 3.65 and 4.57m. By December of this year the

backfill material was changed to consist mostly of

igneous fragments and/or serpentinite and/or other

approved material. The maximum pit area was increased

oficially to 2,OOOm2 in May 1984 and once again a

mixture of cement dust and limestone was authorized as

backfill.

During the following years pit size violations

continued and the extractors were fined by the PR DNR in

February 1984. In May 1985 results of five test borings

done in potential mining areas within the site (Jaca,

Sierra and Rivera, 1985) were submitted. This data

establishes the maximum water-table depth at 4.Om in

addition to supplying an analysis of sample composition.

In July 1985 a new permit was issued. The pit depth was

reduced to 4.5m and backfill material was allowed to

consist of either of the above described rock types. A

50m buffer zone from the MZ was required. These

conditions were kept in the permit issued in December

1986 which is still in effect. This operation has been

continually having problems obtaining a balance between

extraction and backfill ra tes. Consequently, they have

often incurred in violation for exceeding the maximum

pit area and for backfilling with unauthorized material.

The operation has extended into the adjacent mangrove

forest to the south. Currently mining is progressing to

the east.

6.3.3 GEOLOGY AND SOILS

The coastal zone deposits mined in this site

consist of Quaternary Beach deposits (Qb), Alluvium

(Qa), and Swamp deposits (Qs); all of Holocene age

(Krushensky and Monroe, 1978) (Fig. 13). The Qb and Qa

deposits contain sand, cobbles, pebbles, clay and sandy

clay is found in the alluvium. The swamp deposits are

largely mangrove swamps, having a mixture of sand, clay,

and carbonaceous debris from mangrove trees.

The limestone fill was mostly obtained from the

Ponce Limestone (Tp) of Tertiary (Miocene) age. This

limestone is described to be very pale orange to

grayish-orange generally crystalline calcarenite,

containing abundant fossils; thickness is more than 200m

(Krushensky and Monroe, 1978).

The Soil Conservation Service (1979) has defined

the following units in the mined area (.Fig. 13):

Mr- Meros sand. Nearly level soil on benches

along the coast at an elevation slightly above

sea level. The soils formed in textured

sediment that was derived from volcanic rock,

sea shells, and coral. Mapped areas include a

few narrow strips of beach sand that has been

reworked by waves, and small areas of soils that

have a calcareous surface layer. Runoff is

slow; this soil is not subject to erosion. Very

low available water capacity and natural

fertility. Good roadfill; fair sand amounts;

poor topsoil due to its sandy texture.

Se- Serrano sand. Also a nearly leveled,

poorly-drained saline soil on the coastal plains

near the beach in the semiarid area. The soils

formed in coarse textured to moderately fine

textured sediment over coarse textured sediment.

Mapping includes narrow strips of beach sands

that are reworked by the waves and a few areas

of nonsaline Meros soils. Runoff is slow.

6.3.4 HYDROLOGY

Five test wells were drilled in this site to gather

lithologic, water quality, and water-level data. "slug it

injection tests were performed in all wells to determine

relative hydraulic conductivities and/or transmis-

sivities of the site. Well distribution, methodology,

results of tests and well monitoring are described and

summarized in tables and figures in Appendix V.

Test wells number 1 and 2 were drilled in

backfilled areas; wells number 3, 4, and 5 were

installed in unmined areas.

6.3.5 FLORA

The aerial photo interpretation (1971, 1986, 1987)

of this site reveals that pre-mining site conditions

were significantly modified (Fig. 14). In 1971, before

mining began, three major floristic associations were

present in the study site (Fig. 14, 15a.). The upland

portion sustained a deciduos seasonal forest interrupted

by a seasonal marsh. In the southern portion of the site

there was a mangrove forest.

The aerial photos of 1986-87 show that upon

extraction, the seasonal marsh areas became: salt flats,

shallow ponds (Photo 3b), upland areas covered by scrubs

and mangrove swamps dominated by Conocarpus erectus

(Fig. 14)(Photo 3c). The deciduous seasonal forest

changed to sparse young-thorn scrub mixed with salt

flats (Fig. 15b)(Photo 3d). The inner part of the

mangrove swamp, recently extracted and backfilled, is

being covered by sparse pioneer vegetation, although a

great portion of the backfill is still unX7egetated

(Photo 3e, 3f, 3g).

The northern portion of the extracted area was

backfilled approximately ten years ago. At present, the

mining is taking place in the southern section in an

east-west direction over the salt flat areas (Photos 3h,

3i). As the open pit is being filled, material is

deposited on adjacent mangroves and mudflats (Photos 3j,

3k).

Historically, the mangrove swamp deposits were

subject to hand shoveling (Fig. 15b). This type of

mining created several shallow ponds that up to this

date lack emergent vegetation (Photo 31). The effect of

this extraction will not be considered in this study.

PONCE: PLANT SPECIES ADJACENT To THE MINING AREA

I Land dune vegetation

Calotropis procera Ipomoea pes-caprae

Canavalia maritima Spartina patens

Coccoloba uvifera Sporobolus virginicus

11 Basin Mangrove

Avicennia germinas Rhizophora mangle

La uncularia racemosa

III Berm

Batis maritima Spartina patens

Sesuvium portulacastrum Sporobolus virginicus

IV Seasonal marsh

Frimbistylis cymosa Sesuvium portulacastrum

Lippia nodiflora Sporobolus virginicus

V Deciduous Seasonal Forest mixed with seasonal marsh

3@ Bucida buceras Frimbistilys Cymosa

Capparis flexuosa Lippia nodiflora

Cephalocereus royeni Malchra alceifolia

Cyperus ligrualis Pithecelobium unguis-cati

Eliocharis rostellata Prosopis pallida

Ficus citrifolia Sporobolus virgin-:Lcus

PONCE: PLANT SPECIES IN THE MINING AREA

I Salt Flat

Avicennia germinas Sesuvium portulacastrum

Batis maritima

II Pioneer successional vegetation over backfill

Amaranthus an. Heliotropium curassanicum

Argemone mexicana Ricinus communis

Chloris barbata Sonchus oleraceus

Cleome viscosa Sporobolus virginicus

Datura sp.

III Young thorn scrub

Leucaena glauca Prosopis Pallida

Leucaena leucocephala Sesbonia sericea

6.3.6 Fauna

A total of 63 species were reported for this site

as a result of surveys conducted on July 14-17, 1987 and

January 22-23, 1988. The following animal groups and

numbers of species were represented: Crustaceans (5),

Amphibians (2), Reptiles (4), Birds (48) and Mammals

(4).

Five species found are endemic, two are listed by

Federal and State Laws as endangered or threatened.

Another species is included in the Watch List of the

PR NHP.

The salt flats and shallow pond areas were heavily

utilized by herons, egrets, plovers and sandpipers as

feeding and roosting habitats. The periferal zone served

as nesting for Least Tern. Four active nests were found

during the July 15, 1987 survey. Mangrove swamp and

associated unvegetated shallow ponds were used by crabs,

semi-acuatic and terrestrial avian species. The remnant

of a deciduous seasonal forest served as habitat for

resident avian species and is of primary importance in

attracting migrating birds such as the wood warblers.

Avifaunal use of the backfilled area closer to Road PR-2

was limited to exotic species. Reptiles, amphibians and

mammals were found throughout the extraction site and

adjacent areas as well. No fauna was found at the active

mining operation area.

PONCE: FAUNA OBSERVED

Crustacea

Goniopsis cruenttata Uca burgersi

Sesarma sp. U. rapas

U. thayeri

Amphibia

Eleutherodactylus coqui (Endemic)

Leptodactylus albilabris

Reptilia

Ameiva exsul Anolis pulchellus

Anolis cristatellus A. stratulus (Endemic)

Aves

Actitis macularia Eqgretta caerulea

Ardea herodias Eqgretta thula

Arenaria interpres Egretta tricolor

Bubulcus ibis Falco soarverius

(PR NHP Watch List)

Buteo jamacencis Fregata magnificens

Butorides striatus Himantopus mexicanus

Casmerodius albus Lonchura cucullata

Cathartes aura Loxigilla portoricensis

Charadrius wilsonia Mimus polyglottos

C. semipalmatus Mniotilta varia

C. vociferus Myiarchus antillarum

Coereba flaveola (.Endemic)

Columbina passerina Myiopsitta monachus

Crotophaga ani Quiscalus niger

Dendroica adelaidae Pandion haliaetus

D. coronata Parula americana

D. palmarum Passer domesticus

D. petechia Pelecanus occidentalis

D. tigrina (Endangered)

D. striata Pluvialis squatarola

Seiurus noveboracensis

Setophaga ruticilla

Sterna antillarum (Endangered)

Tiaris bicolor

T. olivacea

Tringa melanoleuca

Tyrannus dominicensis

Vireo latimeri (Endemic)

Zenaida asiatica

Z. au,rita

Mammalia

Herpestes auropunctatus Rattus norvegicus

Mus musculus R. rattus

SAN JUAN

MAYAGUEZ

P 0 N C E

lz
Tuq [email protected]
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AP
oz

4N
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lye

. . . .......

CA R (3 E A N S E A

FIG. 12. LOCATION OF PONCE SITE (PIT NO. 16)
Tuq e'

(U.S.G.S. 1962)

Ma
YCC
EnC
Te

CAR 1 6 BE AN S E A

SOI L MAP OF PONCE SITE (PIT NO. 16)

TO Qa
as

Q0 as
Qb

as
Qb

CA RIB BEAN S E A

G E 0 L 0 G I CMAP OF PONCE SITE (PIT NO. 16)

FIG.13. SOIL AND GEOLOGIC MAPS OF PONCE SITE
(S.c.S. 1979; KRUSHENSKY, R.D. AND
MONROE, W. H. 1978)(Key to symbols: Appendix VI)

...........
................
................
.............
.............
4C"SS4 Cc( A S

SOURCE: AERIAL PHOTO 194 T (UPO-TEO)
SOURCE: AERIAL PHOTO I*F( SOURCE: AERIAL PHOTO 1946
FIG.14. V E G E T AT I ON M A P 0 F P 0 N C E S I T

G-71 MANGROVE SWAM
THORN SCRUB EXTRACTION OPE
$A N 0 BEACH SCRAPING 8- EXT
U J-- WATER TABLE (P
El SPARSE SCRUB JUNK SPARSE P(ONEIE
BACKFILLED ACTIVE OPEN PI
SEASONAL MARSH SCRAPING AREA I-JAW., 19 8 6 2
Vn
D(CIDUOS SEASONAL FOREST

FIG.15. CROSS SECTION ILLUSTRATING CHANGES IN PLANT ASSOCIATION AT PONC

DECIDUOUS SEASONAL. FOREST

BASIN MANGROVE

SEASONAL
ECOTONE MARSH
:."I, 'Q
BERM CTIV
OPEN DUNE
WATER
EX TRACTION
PIT

BASIN MANGROVE
SPARSE PIONEER VEGETATION

1-YOUNG THORN SCRUB-1-SALT FLAT-1

OPEN ACTI
WATER OPEN DUN
WATER
ACTIVE EXTRACTION
E X TRAC TION B E LOW WATER TABL E-1 PIT
(BAC K FI L L E D EXTRACTION
PIT
@
PEN
0

Photo 3a Ponce site (Pit #16). Panoramic view
towards the south.

AIP

Photo 3b Partial view towards the south. Created
shallow ponds being filled with limestone.

311W

Photo 3c Partial view towards the east. Backfilled
area. To the left, a stand of Conocarpus
erectus, surrounded by salt flats species;
remnants of the deciduous seasonal forest is
seen in the background.

64 40@

Photo 3d Partial view towards the south. Created
salt flats being covered with limestone
1W backfill ; sparce young-thorn scrub is
seen in the background.

1h
F

Photo 3e - Partial view towards the west. Inner part
0 of the mangrove swamp being covered with
limestone fill.

Ak
W

Phot:03f Sparce pioneer vegetation growing on limestone
backfill.

Photo 3g Partial view towards the east. Unvegetated
backfilled area; remnant of the deciduous
seasonal forest is seen in the background.

niji"
jl"Ai I

Photo 3h Partial view towards the west. Active
wet-pit found in the western portion of
the site. Mangrove and salt flats can be
seen in the background, to the left.
CIZ

Photo 3i Partial view towards the northeast.
Wet-pit found in the eastern section
is being backfilled. In the background,
to the right, is a deciduous seasonal
forest; to the left, a stand of
Conocarpus erectus.

1, . .

Photo 3j - Partial view towards the north. Filled
0 area adjacent to mangrove, mudflats and
shallow ponds.

-WW'

..........

Photo 3k Close-up of mangrove, mud flats and shallow
ponds being covered by limestone fill.

Photo 31 Partial view towards the south. Shallow
ponds created in the inner area of the
mangrove forest.

7.0 PARTIAL MONITORING SITES

7.1 LOIZA

7.1.1 GENERAL INFORMATION

MUNICIPALITY: Loiza PR DNR REGION: San Juan

TOPOGRAPHIC MAP: Can6vanas Quadrangle SITE ACCESS: Road PR-187,
(Fig. 16.) Km 8.5, Bo. Mediania Baja

PIT NUMBERS: 2,3,4 PIT CODE: A Abandoned
Open Pit

APPROX. EXTRACTED AREA AVERAGE DISTANCE FROM:
Same as size of Pits MZ (*): Pit #2: 80m
indicated below Pit #3: 20m
Pit #4: 880m

APPROX. SIZE OF PIT PIT DEPTH:(**)
Pit #2: 157,160m2 (40 cdas.) Max.: Pit #2: 22.7m
Pit #3: 43,219m2 (11 cdas.) Min.: Pit #2: 1.0m
Pit #4: 35,361m2 (09 cdas.)

TYPE OF BACKFILL: N/A

RESTORATION STAGE: None ECOSYSTEMS AND USES:

Pre-mining: Palm groves
Agriculture

Post-mining: Open-water
and herbaceous swamp;
Recreational and fishing

FLOODING SUSCEPTIBILITY
Pit #2: Within the 100 and 500YR floodplain
Pit #3: Within the 500YR floodplain
Pit #4: Within the 100YR floodplain

STORM WAVE SWASH: Not documented

Source: January 24, 1987 aerial photograph.
Source: Bathymetry map prepared by Surveying
Section, PR DNR (September 1977)
Source: FEMA (1981b)

104

7.1.2 MINING HISTORY AND USES

According to available information, sand extraction

in these pits took place before 1972. The pits were

never backfilled and they now serve various purposes as

indicated in Table 1.

7.1.3 FLORA

Mining, agriculture, residential and turistic

ML
developments have modified the floristic components of

the area since mining took place. Therefore, it is

difficult to determine the direct changes resulting from

the extractions. However@ the open bodies of water and

the surrounding swamps can be attributed as being

products of wet-pit operations.

Prior to mining and development, the site

vegetation consisted basically of Palm groves.

Currently, as shown in figure 17, there are many plant

associations present at this site.

105

7.1.4 FAUNA

Fourteen species were recorded for pits *2 and *3.

The following animal groups and number of species were

represented: amphibians (2), reptiles (3), birds (4),

and fishes (5).

Fresh-water fish was recorded for pit #2 during

April 4, 1988. Common gallinule used this pit for

nesting. Three chicks and two adults were observed.

Terrestrial and semi-aquatic birds, amphibians, and

reptiles were seen using transitional areas for

roosting, cover, and feeding.

Several individuals of antillean painted turtle

were observed around wet-pit margins covered by Typha

dominguensis.

In pit *3 only two aquatic birds were observed:

common gallinule and caribbean coot, which is one of the

critical elements of the PR NHP and a candidate to the

Federal List under category number two.

106

LOIZA: FAUNA OBSERVED

Amphibia

Bufo marinus

Leptodactylus albilabris

Reptilia

Anolis cristatellus

A. pulchellus

Pseudemy terrapen

Aves

Bubulcus ibis

Butorides striatus

Fulica caribaea (PR NHP Watch List)

Gallinula chloropus

Piscis

Gobiomorus dormitor

Lepomis sp.

Micropterus salmoides

Tilapia mossambica

T. rendalli

107

Pta
lglesia

3 It
3
1. 7
Hcilndu@as "Ill i1i;
(187)
it

it
7
S drdz
;I' it 711
if .11. if
0 N13.
it 1r,
Ir
7
I,,
if
.... ..... .. ...
38
IT jL ......
1, .6
12. 7.

:IL N
M:,,V 'D 1. A

ra
It*

SANJUAN
RIO GRANOE

LOIZA

FIG. 16 LOCATION OF THE LOIZA SITES (PTTS NO 2.3,4)
(U.S.G.S. 1963)

108

@
FIG. 17. V E G E T A T 1 0 N M A P 0 F
L 0 1 Z A S I T E

..........
@7F

.. . ....

..... . ....
. .. . ...

.........

........ ...

ID-ERBACfOUS SWAMP OLITTORAL- EVERGREEN WOODLAND "I
@!j
SOEVELOPEO AREA a-GRICULrURAL LAND
F----lPALM GROVE BOPEN PIT

R E C R E AT 10 NA LFA C I LI T I E S
ED P ASTURE LAND
MPALm 6 CASUARINA GROVE USCRAPING AREA
EICOAST41. T H I C K E 7 OSANDY BEACH

SOURCE: AERIAL PHOTO JAN.. 190T UPDATED

o 5oo

MtTERS
F

109

8.0 IMPACTS ON WILDLIFE HABITAT

Mining directly affects the ecological succesion of

plants and animals and wildlife habitat. Study findings

that support this are discussed below:

1. Wetlands turned into upland systems. At the
Ponce site, a mangrove swamp and a seasonal marsh were
filled as a result of mining operations that raised land
level.

2. Xerophytic upland systems turned into wetland
and open water systems. The Camuy and Loiza sites,
where wet-pits have been left open, are examples.

3. Man-modified wetlands improved wildlife use of
these areas. As a result of sand scraping in Ponce the
existing wetland was altered, creating shallow ponds and
salt flats favorable for sustaining semi-aquatic fauna.

4. Unmanaged man-made wetlands provided limited
wildlife support. Use of the Camuy site by
characteristic wetland species was poor. No fish were
found in the abandoned wet-pit. This may be partly
explained by: a) the absence of diverse habitats, b) low
nutrient concentrations and organic matter input to the
pond, c) small size of the abandoned pit, in addition to
d) it being a closed system. In contrast, the number of
characteristic wildlife wetland species found in the
Loiza pits was greater; fish species found were
introduced. Both sites sustain a comparable overall
number of species, although the Loiza sites are about
fifteen years older than the Camuy site. This suggests
that unless abandoned wet-pits are specifically managed
to support wildlife, their potential use for this
purpose will be greatly reduced.

5. Removal of food, nesting sites and escape cover
areas for wildlife through the mining process. In Ponce,
a Least Tern nesting area was destroyed and roosting
and feeding areas for various aquatic and semi-aquatic
organisms were dug out and backfilled. In Aguada, forage
areas for the Zenaida Dove and exotic finches were
backfilled, and ghost crab burrows were destroyed.

6. Removal of secondary succesion vegetation and
destruction of wetland at several sites. Deciduous
seasonal forest, seasonal marsh, mangrove swamp, and
coastal thicket were completely removed.

110

7. Natural vegetation succesion occurred at sites
where restoration had not been completed or at abandoned
sites. Invasive pioneer vegetation spread rapidly and
hindered the regeneration of pre-existing vegetative
cover. In Camuy, most of the area is covered by
herbaceous pioneer vegetation that was established at
least five years ago. In contrast, the vegetation cover
found in the northern part of the Ponce site (one of
the oldest mining areas) is sparse and dominated by
Prosopis. Because of the dry climate, natural succession
is expected to be slow in the south coast,

8. At active extraction sites, natural succesion is
hindered when the restoration process, interrupted for a
time, is resumed. Generally, there is a time lapse
between the begining and completion of the restoration
process, that may extend many months, even years. During
this time, pioneer vegetation is established. This
attracts wildlife, especially avian species that feed or
nest in early succession vegetation, as observed in the
Ponce and Aguada sites. Because restoration procedures
are not aimed to create or preserve wildlife habitat,
most incidental habitats created at these times are
later destroyed when restoration is resumed.

9. Areas under active mining were found to have no
wildlife. Similar findings have been described by
Spaulding and Ogden (1968). Surface mining activities
cause constant disturbance and displacement of wildlife.
In some areas this situation is more critical than
others, depending on species diversity, population size
and whether the area was used for foraging, nesting or
roosting activities.

9.0 SUMMARY OF FINDINGS AND CONCLUSIONS

1. Twenty wet-pit mining operations were identified
within the limits of Puerto Rico's coastal zone. Twelve
(60%) wet-pits have been left open; three (15%) have
been backfilled; and five (25%) are active operations.

2. Wet-pit mining operations have proliferated
during this current decade. Most of the operations have
concentrated in the northwest coast of the island.

3. The current regulations to control the
extraction of materials from the Earth's crust do not
contain specific criteria for permit evaluation,
operational methods and restoration requirements for
wet-pit mining.

4. Review of the mining history at selected sites
reveals several management problems:

a. There is a lack of
consistency in the mining and
mitigation procedures established in
different mining permits, even for the
same or similar sites.

b. Extraction, backfilling and
restoration procedures are not always
enforced;

C. Extraction operations are
permitted to continue, even though
violations persist.

5. There are inadequate technical data to properly
evaluate proposed mining sites, techniques and
environmental impacts.

6. Sand mining operations disrupt the natural
coastal zone landforms. Many past extractions have left
open pits; the PR DNR has never executed a Performance
Bond to backfill and restore mining sites.

7. Land levels are lowered by mining. Therefore,
flooding probabilities increase in already flood-prone
areas. The PR PB has confirmed the applicability of
Regulation No. 13 to mining operations. They require of
the PR DNR to determine if the proposed mining activity
will significantly increase flood levels or velocities.

112

8. Wet-pit mining of coastal sand deposits can
locally affect the ground-water hydrology of coastal
zones. It can result in the lowering of water levels at
the dune area with eventual migration inland of the
freshwater-saltwater interface. The extent to which
this will occur depends on climatic and hydrogeologic
conditions of the area. With the information obtained,
it is not possible to determine a critical pit size or a
maximum length of time a pit should remain open before
significant changes begin to take place.

9. At present, wet-pits are required to be
backfilled. The general practice has been to backfill
extracted sites to the minimum requirements (1m above
MSL). The most common fill material used is limestone,
followed by residual sand, volcanic sand and topsoil.
Construction debris, junk, and cement dust was
corroborated to have been used in some places.

10. Backfill used to restore the site will not
severely alter the ground-water system, as long as the
fill material has similar hydraulic properties as the
original extracted sand. When local hydraulic
conductivities in the aquifer are significantly altered
by the backfill used, natural ground-water flow
patterns will be permanently distorted.

11. In the area of Camuy, the sand-extraction site
has been partially backfilled with apparently high
permeable material. As a result, surrounding heads in
the local shallow aquifer have probably been permanently
depressed.

12. In Aguada, sand mining operations appear to
have caused local changes in the hydrology of the site.
The area where sand extractions have occurred was
backfilled with materials of lower permeability than the
original sand deposits. As a result, a water-table
mound apparently has developed which seems to have
inhibited a decline of water levels in the adjacent
dune. The water-table mound could probably have also
inhibited migration of seawater into the open pit.

13. The wet-pit in Ponce has locally increased the
aquifer permeability. As a result, surrounding water
levels in the aquifer and in the dune have dropped by as
much as 3 feet.

14. Mining processes directly affect wildlife
habitat and the ecological sucession of plant and animal
population:

113

a. In Ponce, a productive system
in terms of structure and function
that provided habitat for aquatic,
semi-aquatic, and terrestrial species
was altered. The extraction modified
and expanded part of the wetland,
turning it into feeding and nesting
areas. Final restoration displaced the
species found in the wetland.

b. Although the coastal vegeta-
tion once present at the Aguada site
was described by Lugo (1983) as
apparently unproductive in terms of
its low structural complexity, it
provided stability to the beaches and
30 dunes. Using adjacent areas exhibiting
similar pre-mining conditions for
comparison, it can be determined that
fauna species present in the extracted
area previous to mining was scarce.
Naturally revegetated extraction sites
became a source of food and attracted
an increased number of terrestrial
species. Final restoration displaced
the species found in the extracted
area.

C. The Camuy and Loiza sites,
both originally upland systems, were
turned into wetland and open-water
systems.

15. Current restoration practices do not
incorporate efforts to mitigate loss of fish or
terrestrial habitat through either selective planting
of appropiate species or creation of replacement
habitats.

16. Wet-pit mining impact on wildlife habitat is
site specific and is dependant on extraction and
restoration procedures. Unless abandoned wet-pits are
specifically managed to support wildlife, their
potential use for this purpose will be greatly reduced.

114

BIBLIOGRAPHY

Brooks, Denis R., 1988. Wetlands rehabilitation
following mineral sands mining in Australia, in
1988 Mine Drainage and Surface Mine Reclamation
Conference. American Society for Surface Mining and
the United States Department of the Interior,
Bureau of Mines and Office of Surface Mining
Reclamation and Enforcement, Pittsburgh, PA.
pp. 146-153.

Dittberner, P. L., Schamberger, M., and Haynes, R.,
1983. A reclamation, planning and evaluation
process based on the habitat evaluation procedures,
in Proceedings of the Reclamation and Phosphate
Industry Symposium, Clearwater Beach, Florida, 26-
28, January, 1983. Florida Institute of Phosphate
Research Publication No. 03-036-010. pp. 411-427.

DuBois, R., and Towle, E.L., 1985. Coral harvesting
and sand mining management practices, in Clark,
J.R., ed., Coastal resources management development
case studies. Renewable Resources Information
Series, Coastal Management Publication No.3, 289 pp

FEMA, 1982. Flood Insurance Rate Map. Community-
Panel number 720000-0010B. Panel 10 of 325.

, 1981a. Flood Insurance Rate Map. Community-
Panel number 720000-0277B. Panel 277 of 325.

1981b. Flood Insurance Rate Map. Community-
Panel number 720000-0065B. Panel 65 of 325.

1 1978. Flood Insurance Rate Map. Community-
Panel number 720000-0025A. Panel 25 of 325.

Gilbert, T., Kinm, T., and Barnett, B., 1981. An
assessment of wetland habitat establishment at a
Central Florida Phosphate Mine Site. U. S.
Department of the Interior, Fish and Wildlife
Service. FWS/OBS-81/38. 96pp.

Haynes, Ronnie J., Bassin, Jay N., and Huber, Richard
T., 1982. Noncoal minerals reclamation and resource
issues in the southeastern United States, in 1982
Symposium on Surface Mining Hydrology ,
Sedimentology and Reclamation. University of
Kentucky, Lexington, Kentucky. pp. 365-376.

115

Hudy, M. and Gregory, R. W., 1984. Some Limnological
Characteristics of eight limestone excavations in
South Florida. U. S. Department of the Interior
Fish and Wildlife Service. FWS/OBS-83/34. 84 pp.

* Jaca, Sierra and Rivera, 1985. Results of five test
borings: Potential sand borrow area. El Tuque Ward,
Ponce, Puerto Rico. Jaca, Sierra, and Rivera
Geotechnical Engineers and Testing Laboratories.
3pp.

* Krushensky, Richard D., and Monroe, Watson H., 1978.
Geologic map of the Pefiuelas and Punta Cuchara
Quadrangles, Puerto Rico. Scale 1:20,000. U.S.G.S.
Map 1-1042.

* Lugo, A. E., 1983. Coastal Forests of Puerto Rico, in
Lugo, Ariel, ed., Los Bosques de Puerto Rico.
Institute of Tropical Dasonomy, U. S. Forest
Service and Puerto Rico Department of Natural
Resources. pp. 177-203.

* Monroe, Watson H., 1969. Geologic map of the Aguadilla
Quadrangle, Puerto Rico. Scale: 1:20,000. U.S.G.S.
Misc. Geol. Inv. Map 1-569.

9 1963. Geology of the Camuy
Quadrangle, Puerto Rico. Scale: 1:20,000. U.S.G.S.,
Map GQ-197.

Morrison, D. G. 1982. Principles of Revegetating
Mined Lands, in Wildlife Values of Gravel Pits
Symposium Proceedings. University of Minnesota
Crookston, Minnesota. Miscellaneous Publication 17-
1982. Agricultural Experiment Station University of
Minnesota at St. Paul, Minnesota. pp. 51-58

Newport, B. D. and Moyer, J. E., 1974. State-of-the-
Art: Land and Gravel Industry. National
Environmental Research Center. U. S. Environmental
Protection Agency, Office of Research and
Development. Carvallis, Oregon. EPA 660/2-7-74-066.
40pp.

Potter, Janit Llewellyn, 1983. Reclaiming sand and
gravel pits for wildlife, in 1983 Symposium on
Surface Mining, Hydrology, Sedimentology and
Reclamation. University of Kentucky, Lexington,
Kentucky. pp. 315-319.

116

* PRCMP, 1978. Puerto Rico Coastal Management Pro-gram
and Final Environmental Impact Statement. U. S.
Dept. of Commerce, National Oceanic and Atmospheric
Administration, Office of Coastal Zone Management.

* Puerto Rico Department of Natural Resources (PR DNR),
1978. Reglamento para regir la extracci6n de
materiales de la corteza terrestre. PR DNR, 44 pp.

* Puerto Rico Planning Board (PR PB), 1972. Reglamento
sobre control de edificaciones y desarrollo de
terrenos en zonas susceptibles a inundaciones. PR
PB, 22pp.

* Soil Conservation Service (SCS), 1982. Soil Survey of
Arecibo Area of Northern Puerto Rico. 169pp.

1979. Soil Survey of
Ponce Area of Southern Puerto Rico. 80pp.

1975. Soil Survey of
Mayaguez Area of Western Puerto Rico. 296pp.

* Soto, Alejandro E., 1982. Evaluation of beach erosion
in relation to sand extraction along a 258 meter
stretch of coast in An'asco Bay. 3 pp.

* Spaulding, W. M. and Ogden, R. D. , 1968. Effects of
surface mining on the fish and wildlife resources
of the United States. U. S. Department of the
Interior, Fish and Wildlife Service. 51 pp.

* U.S.G.S., 1972. Topographic map of the Camuy
Quadrangle, Puerto Rico. Scale: 1:20,000.

1963. Topographic map of the Rio Grande
Quadrangle, Puerto Rico. Scale: 1:20,000.

1962. Topographic map of the Punta Cuchara
Quadrangle, Puerto Rico. Scale: 1:20,000.

P 1960. Topographic map of the Aguadilla
Quadrangle, Puerto Rico. Scale: 1:20,000.

VAzquez-Ifiigo, Leovigildo, 1979. Actividades de
extracci6n en Areas costaneras: Su efecto en las
aguas subterrAneas. 5 pp.

117

V61ez, Pedro, 1983. Estudio preliminar geol6gico para
la extracci6n de arena sobre y bajo el nivel
freAtico, en la finca del Sr. Francisco Raffucci,
localizada en el Barrio Rfo Grande, Aguada, Puerto
Rico. 13pp.

Zack, Allen, 1983. Sand removal and resulting effects
on ground-water flow in the vicinity of the Camuy
Mangrove Forest, Puerto Rico. U.S.G.S. Water
Resources Investigations 83, 21 pp.

Referred to in text

118

-1

d1b,

APPENDIX I:
"NOTE TO THE FILE" AUTHORIZING EXTRACTIONS
BELOW THE WATER-TABLE,
MARCH 12, 1981

119

NATURALES 1981
PARA EL EXPEDIENTE

En cl dia de hoy 12 de marzo de 1987 se efectus wra reunion con cl dr. Fred v
Soltero Harrington , Secrctario del Departameto de Recursas Naturales, para someterle
conteza terrestre baja el nivel frearico (ver carts del 11 de marzo de 1987). A esta
reunion asisticron; esl Sr. Edgar Rosario, Secretario Auzilar Tnt. del Area De Opera-
ciones, el Tna. Carlos M. Sanitara, Ascesr Tecrico del Area de Operaciones y La scrora
Glenda Hernandez, Director de la Oficina Regional de Aguadilla.

De esta reunion se desprende lo siguicrte:
1. El Dr. Fred V.Soltero Harrington autoriz6 a que se extraycre material
bajo cl nivel freatico.
2. Se le exigira un "Performance Bond" de $100,000 d6lares. ok
3. Se le pcrmitira crear fosas no mayores de 30M x 30M
4. Sc dividera la finca en tres (3) partes iguales y se autorizara la
extraccion en la pimera tercera parte (1/3). Una vez efectuado los
trabajos en esta parte, se efectuara una inspection para determinar si
amerita o si merece, desde el punto de vista tecnico i continuar los
trabajos en el resto de la finca.
5. Debcra presentar al departamento un plan de restauracion y reforestaci6on
al area para la consideracion del mismo.
6. Debra presentar al Departamento un plan de trabajo para la consideracion
del mismo.
7. Debera prescntar al Departamento evidencia le los contratos que efectae
para obtencer el relleno que utilizaran el los trabajos de restauracion.
8. Se le asignara un guardian de la Region de Aguadilla, el cual estara
presente en el lugar de extracion y sometera un informe semanal de
los trabajos alli autorizados.
9. Debera someter recomendncioncs de la oficina de conservacion de sucles
para la restauracion de ara.

Rafacl Same, Jefe Seccion
Corteza Terrestre

I-1

estado lubre asociado de pueric rico, Departamento de recursos naturales
officina avendia de munoz rivera, parade 3, san juan putero rico
deircoronal 5887, pureta do tierra, Puerto Rico 00906

-N

.-N

APPENDIX II:
PLANNING BOARD LETTER
DATED JUNE 24, 1980
ok

120
0

24 de junio de 1980

Hon.Fred V. Soltero Harrington
Secretarion
Departamento do Recursos Naturales
Apartako 5887
Puerta de Ticrra, Puerto Rico 00906

Estaimado senor Soltero Harrington:

En atencion a lo planteado en su conumicaticion del 13 de
junio de 1980, le confirmamos que ofectivamente el Reglamento
Sobre Control de Edificaiones y Desarrollo de Terrenos en
Zonas Susceptibles a Inundiciones aplica a los permisos para
la extraccion de material de la corteza terrestre.

La extraccion en zona inundable 1 se podria autorizar si
se determinara previamente que dicha activadad no tendra el
efecto de aumentar el nivel de inundacion o la velocidad de
las aguas. Cada caso debe ser estudiado y evaluado en sus
meritos.

Cordialmente,

Miguel A Rivera Rios
Presidente

1979 ANO DE LOS PANAMERICANOS
II-1 24496

-1

90,

APPENDIX III:
PLANNING BOARD LETTER
DATED NOVEMBER 22, 1985

121

ESTADO LIBRE ASOCIADO DE PUERTO RICO Contro Gubernamental Minillas, Edif. Norte
OFICINA DEL GOBERNADOR Ave. De Diego, Pda. 22
JUNTA DE PLANIFICACION Aptdo 41119, San Juan, P.R. 00940 - 9985

22 de noviembre de 1985

Ing. Ruth D. Carreras
Secretaria Auxiliar
Area de Planificaci6n
Departamento de Recursos Naturales
Apartado 5887
San Juan, Puerto Rico 00906

Me refiero a la solicitud que nos hace en su reciente comu-
nicacion en cuanto a la aplicabilidad de las disposiciones del
Reglamento de Planificaci6n Num. 13 a los casos de solicitudes
de permisos de extracci6n de material de la corteza terrestre
en terrenos que radiquen en zonas inundables.

Sobre el particular le informo que las disposiciones del
referido reglamento aplican a todas las areas inundables para
las cuales esta Junta de Planificacion haya adoptado Mapas de
Zonas Susceptibles a Inundaciones o Mapas de Zonas Provisionales
Inundables. Los usos que se propongan en estas areas, sean en
estructuras o sobre el terreno, deben cumplir con las disposicio-
nes reglamentarias establecidas. En el caso que nos ocupa, son
de particular aplicacion, sin limitarse a ellas, las disposicio-
nes contenidas en la Subseccion 6.02 (Usos en Zona-l).

Aunque normalmente, estas charcas no restan capacidad hidrau-
lica, en la Zona-2 se debe requerir que se demuestre mediante un
analisis hidraulico que otras areas adyacentes en Zona-2, no pasa-
ran a formar parte del cauce mayor del rio o quebrada y por ende
deban ser reclasificadas a Zona-1.

Estamos a su disposicion para servirle.

Cordialmente,

Adalberto Colon
Vice-Presidente
III-1

APPENDIX IV:
OUTLINE: TASK 7.2

-1

122

OUTLINE: TASK 7.2

LITERATURE SEARCH

1. Library research in local agencies and universities

2. Information request from selected agencies and
organizations outside Puerto Rico

3. Preparation of reference file

4. Acquisition of relevant articles

5. Reading, analysis and application of articles

DEVELOPMENT OF METHODOLOGY AND DATA BASE

1. Island-wide inventory of extraction sites

a. Permit file research (Permits Office, DNR)

b. Form preparation in large index cards to include
key file information per study case

c. Aerial photo evaluation and field inspection of
areas to verify file information, as needed

d. Preparation of inventory map of extraction sites
to include general site location, pit code

2. Evaluation and selection of monitoring sites

3. Individual monitoring site study and description

a. Detailed analysis of maps (topographic, geologic,
hydrologic, soil, ecologic, others) and photos
(aerial and land)

b. Field work to collect data to prepare detailed
site description: study of the physical, chemical,
biologic, and ecologic parameters of each site

c. Determine quantity and location of observation
wells to be installed per selected site, establish
a monitoring program

IV-1

OUTLINE: TASK 7.2 (CONT.)

d. Tabulation of collected pit data to include
but not be restricted to the following:

1) Open-pits active/inactive

a) bathymetry b) flora/fauna distribution
c) adjacent ground-water levels/conductivities
d) conductivity e) experimental fishery

2) Closed pit areas

a) type and distribution of backfill
b) around-water level in filled areas and
adJacent terrain
c) ground-water conductivity
d) flora/fauna distribution
e) land use

e. Preparation of detailed map of each monitoring
site to include identification of past and present
extent of work area, fill, vegetation and well
distribution, location of nearby bodies of water,
and other pertinent data

f. Detailed study of gathered monitoring site
information

a) Integration and analysis of collected data
b) Summary of findings
c) Recommendations based on findings

IV-2

APPENDIX V:
PROGRESS REPORT: GENERAL HYDROGEOLOGY OF SELECTED
COASTAL SAND EXTRACTION SITES IN PUERTO RICO
0

123
a

PROGRESS REPORT

General Hydrogeology of
0 Selected Coastal Sand
Extmction Sites in
Puerto Rico

0 By
Arturo Torres-Gonzalez,
Bruce Green
and
0 Angel Roman-Mas

UNITED STATES GEOLOGICAL SURVEY
WATER RESOURCES DIVISION
SAN JUAN. PUERTO RICO

V-i

CONTENTS

Page

Introduction ............................................... 1
Test wells ................................................. 3
General lithology ..................................... 3
Water quality .............................................. 24
Water levels ............................................... 27
Hydraulic Tests ............................................ 35
Results of hydraulic tests at wells in sand extraction
sites at Ponce, Camuy and Aguada ..................... 37
Summary and conclusions .................................... 43
Appendix A ................................................. 45
Appendix B ................................................. 51
Appendix C ................................................. 58

ILLUSTRATIONS

Page

Figure-1. Map showing location of sand extraction sites . . . 2

2. Map showing location of test wells in the Ponce
sand extraction site . . . . . . . . . . . . . . . 5

3. Map showing location of test wells in the Camuy
sand extraction site . . . . . . . . . . . . . . . 6

4. map showing location of test wells in the Aguada
sand extraction site . . . . . . . . . . . . . . . 7

5. Graph showing lithology and water quality data
for test well 1 at Ponce . . . . . . . . . . . . . 8

6. Graph showing lithology and water quality data
for test well 2 at Ponce . . . . . . . . . . . . . 9

7. Graph showing lithology and water quality data
for test well 3 at Ponce . . . . . . . . . . . . . 10

8. Graph showing lithology and water quality data
for test well 4 at Ponce . . . . . . . . . . . . . 11

V-ii

ILLUSTRATIONS Continue

Page
Figure 9. Graph showing lithology and water quality data
for test well 5 at Ponce . . . . . . . . . . . . . 12

10. Graph showing lithology and water quality data
for test well 6 at Camuy . . . . . . . . . . . . . 13

11. Graph showing lithology and water quality data
for test well 7 at Camuy . . . . . . . . . . . . . 14

12. Graph showing lithology and water quality data
for test well 8 at Camuy . . . . . . . . . . . . . 15

13. Graph showing lithology and water quality data
for test well 9 at Camuy . . . . . . . . . . . . . 16

14. Graph showing lithology and water quality data
for test well 10 at Camuy . . . . . . . . . . . . 17

15. Graph showing lithology and water quality data
for test well 11 at Camuy . . . . . . . . . . . . 18

16. Graph showing lithology and water quality data
for test well 12 at Aguada . . . . . . . . . . . . 19

17. Graph showing lithology and water quality data
for test well 13 at Aguada . . . . . . . . . . . 20

18. Graph showing lithology and water quality data
for test well 14 at Aguada . . . . . . . . . . . . 21

19. Graph showing lithology and water quality data
for test well 15 at Aguada . . . . . . . . . . . . 22

20. Graph showing lithology and water quality data
for test well 16 at Aguada . . . . . . . . . . . . 23

21. Graph showing specific conductance distribution
in the Ponce sand-extraction site . . . . . . . . . 25

22. Graph showing specific conductance distribution
in the Aguada sand-extraction site . . . . . . . . 26

23. Map showing water-table configuration in the
Ponce sand-extraction site . . . . . . . . . . . . 28

24. Graph showing hydrogeologic cross section along
the Ponce sand-extraction site . . . . . . . . . . 29

25. Map showing water-tables configuration in the
Camuy sand-extraction site . . . . . . . . . . . . 30

V-iii

ILLUSTRATIONS Continue

Page

Figure 26. Graph showing hydrogeologic cross section along
the Camuy sand-extraction site . . . . . . . . . . 31

27. Map showing water-table configuration in the
Aguada sand-extraction site . . . . . . . . . . . 33

28. Graph showing hydrogeologic cross section along
the Aguada sand-extraction site . . . . . . ... . 34

29. Map showing hydraulic conductivity computed for
test wells in the Ponce sand-extraction site . . . 39

30. Map showing hydraulic conductivity computed for
test wells in the Camuy sand-extraction site . . 40

31. Map showing hydraulic conductivity computed for
test wells in the Aguada sand-extraction site 42

Appendix A Hydraulic conductivities from slug tests in
test wells 1-5 at Ponce . . . . . . . . . . . . 45-50

Appendix B Hydraulic conductivities from slug tests in
test wells 6-11 at Camuy . . . . . . . . . . . . 51-57

Appendix C Hydraulic conductivities from slug tests in
test wells 12-16 at Aguada . . . . . . . . . . . 58-63

TABLES

Page
Table 1. Hydraulic conductivities at test wells in sand
extraction sites at Ponce, Camuy, an Aguada . . . 38

V-iV

INTRODUCTION

In July 1987, the Puerto Rico Department of Natural
Resources (PRDNR) requested the assistance of the United States
Geological Survey (USGS) to conduct a hydrologic investigation
of sand extraction sites along the coast of Puerto Rico. The
PRDNR regulates the sand extraction industry by granting permits
and approving extraction sites, techniques and rehabilitation
methods. The department lacked the technical means to evaluate
the effects of sand extraction by open-pit mining on the ground-
water hydrology of coastal zones.

The USGS study addresses the lithology, water quality,
water levels, flow patterns, and hydraulic properties of coastal
aquifers in sand-extraction areas located in Ponce, Camuy and
Aguada (fig. 1). These comercial sand extraction sites represent
different coastal ecological zones on different stages of the
open-pit mining process. Previous studies (Zack 1982) indicate
that sand extraction from dunes can lower water tables and cause
degradation of adjacent environments.

A total of sixteen test wells were drilled to depths ranging
from 8.5 feet to 37 feet. The wells were monitored for changes in
water level and water quality from August to December 1987.
Hydraulic tests (slug-injection) were completed in September 1987
to define the hydraulic properties at each well site. Data
compilation and analysis, through early 1988, culminated in this
final report.

V-1

67*00, es 30' 66 000,

18*30' CA Y 6AN JUAN

-4
AQUADA

rv 18600, PONCE

0 10 20 30 KILOMETE
11 2,
.JSAND EXTRACTION AREA
0 10 20 .30
I

Figure I.-- Location of send extraction areas Included In this study

TEST WELLS

A total of 16 shallow test wells were drilled in the Ponce,
Camuy, and Aguada study areas (fig. 1) to gather lithologic,
water quality, and water-level data .

Test wells no. 1, 2, 3, 4, and 5 were drilled in Ponce, east
of Laguna de las Salinas and south of El Tuque community in Barrio
Canas (fig. 2). The wells were drilled to depths ranging from
14 feet to 37 feet, generally in a sandy matrix. All test wells
except no.3 collapsed at the bottom when drill stems were removed
out of the borehole. Casings of PVC with 5-ft long screens were
installed at each hole (figs. 5 to 9).

Test wells no. 6, 7, 8, 9, 10, and 11 were drilled in Camuy,
south of Punta Penon in Sector Membrillo (fig. 3). The wells
were drilled to depths ranging from 9 feet to 19 feet in a site
mostly characterized by limestone fill material. Wells no. 6, 10,
and 11 collapsed at the bottom when drill stems were removed. Loc-
ation of screens are shown in Figures 10 through 15.

Test wells no. 12, 13, 14, 15, and 16 were drilled in Aguada
between Rio Grande on the west and Cano de Santi Ponce on the east
(fig. 4). The wells were drilled to depths between 15 feet and
42 feet into sand deposits and limestone. Test wells no. 12, 14,
and 15 collapsed at the bottom when drill stems were removed from
the hole. Location of screens are shown in figures 16 through 20.

General Lithology
----------------
The general lithology of test wells 1 to 16 is described
below:

TW-1 PONCE: The upper 5 feet of the well was fill material con-
sisting of dark-yellow sand mixed with organic mat-
ter and limestone rubble. The lower 7 feet were med-
ium-grained sand changing to fine sand mixed with
gravel.

TW-2 PONCE: From 0-4 feet medium to fine sand with organic mate-
rial, from 4-9 feet fine sand with increasing quanti-
ties of shells.

TW-3 PONCE: Clay mixed with fine sand and shells from 0-4 feet
changing to dry to moist clay with limestone rubble
and shell fragments to the bottom at 37 feet.

TW-4 PONCE: Dark-yellowish sand was found from 0-4 feet followed
by fine to medium gray-green sand to 29 feet. Lime-
stone occured from 29-34 feet.

V-3

TW-5 PONCE: Gray-green sand mixed with shells changing to predo-
minantly sand to 10 feet.

TW-6 CAMUY: Light brown coarse sand mixed with some organic mate-
rial 0-4 feet. This changed to cemented sand to the
bottom of the hole at 9 feet.

TW-7 CAMUY: A dark yellow-brown sandy clay mixed with topsoil was
found to 3 feet. Cemented sand to the bottom at 8.5
feet.

TW-8 CAMUY: The entire depth of 11.5 feet was composed of silty.
sand with some cemented sand.

TW-9 CAMUY: Topsoil with limestone fragments and sand to 3 feet,
followed by sandy, silty clay to 7 feet. From 7 feet
to the bottom, coarse-cemented sand was encountered.

TW-10 CAMUY: The entire length was composed of dark yellow-brown
silty sand mixed with limestone rubble.

TW-11 CAMUY: Yellow-brown clay with topsoil predominated from 0-4
feet. From 4-9 feet clayey sand changed to mostly
sand. Cemented sand with yellow-orange clay followed
to the bottom at 16 feet.

TW-12 AGUADA:Predominantly yellow-brown sand with traces of cemen-
ted sand the entire hole.

TW-13 AGUADA:Dark yellow-brown fine sand from 0-3 feet. Dark yel-
low limestone was found to the bottom of the hole at
14 feet.

TW-14 AGUADA:Mostly fine sand with traces of limestone rubble 0-3
feet. A dark orange limestone followed to the bot-
tom of the hole at 15 feet.

TW-15 AGUADA:Sand with topsoil was found 0-3 feet. Medium-grained
sand changing to coarse grained sand continued to the
bottom at 11 feet.

TW-16 AGUADA:A hard yellow-orange limestone was found the entire
23 feet of the well.

V-4

VjA
IC
0

C/
A g k i a
J 9

13.0

It
3

I it

f
C2)

EXPLANATION

t1 0 LOCATION AND NUMBER
vill

CROSS SECTION A-A'

bign na 0f

f 10
fle las SaliMIS OPEN PIT

0 .5

Figure 2.--Location of test wells ln4he Ponce sand-extraction site,

Pehon de Aft jera

Pta Punfilla 7

lou
/0 (Dar-

F
'ERR

x)7 35 It

to
It It "I
OPO
T161 'IF
it. al. K Im! 11
;@ It
Mc'mb jJ1
It
4, 'Y A R "j, i
501\ Y
Pit
75

141
EXPLANATION

4.
F_ I)
LOCATION AND NUMBER OF TEST WELL

CROSS SECTION A-A' it

it
it

OPEN PIT

wa-

KIL
U, -6 OMETER

Figure 3.--Location of test wells In the Camuy sand-exitraction site.

2 1d 00-

4
- r * D)E
T@ 1
FR AN
RfO G R A. -;d
3 1

48
j00

xG
Matlas Y
(7

EXPLANATION

LOCATION AND NUMBER OF TEST WELL

CROSS SECTION A-A'

OPEN PIT

0
KILOMETER

Figure 4.-Location of test welLs in the Aguada sand-extraction site.

V-7

TWIIPONCE

0 SPECiric

CONDUCTANCE CHLORIDES

2980 950

SAND

3600 1125

5 5250 1750

ZSCREEN

6000 2000

SAND, GRAVEL

FIGURE 5.--LITHOLOGY AND WATER-QUALITY DATA

FOR TEST WELL 1 AT PONCE

v- a

TW2 PONCE

0 SPECIFIC

CONDUCTANCE CHLORIDES

FINE-MEDIUM SAND

SAND WITH SHELLS
SCREEN::

825 154

FIGURE 6.-- LITHOLOGY AND WATER-QUALiTY DATA

FOR TEST WELL 2 AT PONCE

V--q

TW3 PONCE

SPECinc
CONDUCTANCE CHLORIDES
0

SAND WITH CLAY

CLAY 625 103

CLAY WITH LIMESTONE 980 220

15 740
21PO

25 CLAY

SCREEN
3 5

40L

rIGURE 7.--LITHOLOGY AND WATER-QUALITY DATA

rOR TEST WELL 3 AT PONCE

V- 10

TW4 PONCE

SPECIFIC
CONDUCTANCE CHLORIDES
0

SAND AND GRAVEL
3850 1350

5 4050 1000

4300 1090

15
FINE-MEDIUM SAND

30
SCREEN LIMESTONE

35 9250 2500

FIGURE 8,--LITHOLOGY AND WATER-QUALITY DATA

FOR TEST WELL 4 AT PONCE

v- 11

TW5 PONCE

0 SPECIFIC

CONDUCTANCE CHLORIDES

FINE SAND

13,500 5,500

5 1S,000 6600

MEDIUM-COARSE SAND

SCREEN 38,000 >10,000

50,000 >10.000

FIGURE 9.--LITHOLOGY AND WATER-QUALITY DATA

FOR TEST WELL 5 AT PONCE

V- 12

TW6 CAMUY

0 SPECIFIC

CONDUCTANCE CHLORIDES

340 40

COARSE SAND

750 50

1000 2 5 0

SCREEN

CEMENTED SAND

1250 300

FIGURE IO.--LITHOLOGY AND WATER-QUALITY DATA

FOR TEST WELL 6 AT CAMUY

V- 13

TW7 CAMUY

0 SPECinc

CONDUCTANCE CHLORiDCS

SANDY CLAY 1050 225

1300 250

1600 500
CEMENTED SAND
ZSCREEN_

1900 700

FIGURE ii.-- LITHOLOGY AND WATER-QUALITY DATA

FOR TEST WELL 7 AT CAMUY

V- 14

TW8 CAMUY

0 SPECiric
CONDUCTANCE CHLORIDES

350 35

SILTY SAND WITH 350 3 5

CEMENTED SAND 550, 40

SCREEN

900 225

FIGURE 12.--LITHOLOGY AND WATER-QUALITY DATA

FOR TEST WELL 8 AT CAMUY

V- 15

TW9 CAMUY

0 SPECIFIC
TOPSOIL AND SAND CONDUCTANCE CHLORIDES

1000 260

5
SANDY-SILTY CLAY

1000 260

10 1600 500

COARSE AND

2400 800

CEMENTED SAND

15 2600 900
SCREEN

2775 925

FIGURE 13.--LITHOLOGY AND WATER-QUALITY DATA

FOR TEST WELL 0. AT CAMUY

V- 16

TW10 CAMUY

0 SPECIFIC
CONDUCTANCE CHLORIDES

900 220
SILTY SAND WITH

LIMESTONE RUBBLE

1025 250
SCREEN

1175 260

FIGURE 14.--LITHOLOCY AND WATER-QUALITY DATA

FOR TEST WELL 10 AT CAMUY

V- 17

TW11 CAMUY

0 SPECIFIC

CONDUCTANCE CHLORIDES

CLAY

625 54

CLAYEY SAND

1000 260

1200 265

CEMENTED SAND

@ZSCREEN:: WITH CLAY

15 1200 265

FIGURE 15.--LITHOLOGY AND WATER-QUALITY DATA

FOR TEST WELL 11 AT CAMUY

V_ In

TW12 AGUADA

0 SPECIFIC
CONDUCTANCE CHLORIDES

15
FINE SAND
3490 1325

5100 2000

20 &250 2400

24,000 E000

-30 ZSCREEN_
37,500 LESS THAN 10,000

4 0

FIGURE 16.--LITHOLOGY AND WATER-QUALITY DATA

FOR TEST WELL 12 AT AGUADA

V-19

TW13 AGUADA

SPECIFIC

CONDUCTANCE CHLORIDES

FINE SAND

900 250

1000 260

LIMESTONE

1400 320

L
@CREE

-7 1800 400

FIGURE 17.--LITHOLOGY AND WATER-QUALITY DATA

FOR TEST WELL 13 AT AGUADA

V-20

TW14 AGUADA

0 SPECIFIC

CONDUCTANCE CHLORIDES

FINE SAND

2490 800

2800 900
LIMESTONE

3450 1100

SCREEN-

6000 2000

FIGURE 18.--LITHOLC)GY AND WATER-QUALITY DATA

FOR TEST WELL 14 AT AGUADA

V- 21

TW15 AGUADA

0 SPECIFIC

CONDUCTANCE CHLORIDES

SANDY SOIL

MEDIUM-COARSE

SAND

550 100

15
0 FIGURE 19.--LITHOLOGY AND WATER-QUALiTY DATA

FOR TEST WELL 15 AT AGUADA

V- 22

Ilk

TW16 AGUADA

SPECIFIC

CONDUCTANCE CHLORIDES

LIMESTONE

370 36

405 45

20
--SCREEN

700 E5

25
FIGURE 20.--LITHOLOGY AND WATER-QUALITY DATA
FOR TEST WELL 16 AT AGUADA

V- 23

WATER QUALITY

Water quality analyses for this study were limited to specific
conductance and chloride determinations for specific depth samples
collected at each test well during a field trip on November 1987
(figs 5 to 20). Samples were also collected for active open pits found
in Ponce and Aguada (figs. 21 and 22). Specific conductance was field
measured while chloride analysis was conducted at the USGS laboratory
using the specific-ion probe technique.

Chloride and specific conductance increase toward the coast and
with depth as a result of seawater intrusion. In Ponce, as a response
to the drier climatic conditions, a very thin freshwater lens and a
more inland freshwater-saltwater interface is observed in comparison
to Aguada and Camuy. The thicker freshwater lenses at Camuy and
Aguada, due to higher rainfall, inhibit the inland migration of the
interface.

The highest values for specific conductance and chloride were
obtained at Ponce. In test wells at Ponce, specific conductance values
ranged from 625 to 50,000 microsiemens per centimeter, whereas
chlorides ranged from 103 to greater than 10,000 miligrams per liter
(figs. 5 to 9). Specific conductance in the open pit at Ponce increased
with depth from 1350 at the surface to a maximum of 14,000 usiemens/cm
at a depth of 6 feet (fig.21). In Camuy test wells specific conductance
ranged from 340 to 2,775 usiemens/cm whereas chlorides ranged from 40 to
925 mg/l (figs. 10 to 15). In the Aguada test wells specific conductance
ranged from 370 to 37,500 usiemens/cm and chlorides ranged from 36 to
slightly less than 10,000 mg/l (figs. 16 to 20). In the open pit at
Aguada, values of specific conductance remained constant at 500
usiemens/cm both areally and with depth (fig.22).

Based on a conceptualized model of coastal zones, it is possible to
infer that sand extraction by the open-pit method may affect the rela-
tive position of the freshwater-seawater interface. The removal of
saturated sand deposits can locally alter the permeability of the
aquifer matrix thus, allowing the interface to either move inland or
seaward. The overall displacement of the interface will be defined by
the duration of the open pit mining and the hydrogeologic characteris-
tics of each site. The inland migration of the interface and the
resulting increase in salinity may stress the local ecosystems. In
arid areas, such as Ponce, displacement of the interface results in the
development of hypersaline conditions. This would result in damage to
the nearby mangrove forest which is already at the limit of its adaptive
capabilities. The displacement of the interface also affects the
freshwater lens within the sand dunes and its plant community. The
health of the plant community and its stabilizing function on the dunes
would be compromised.

V-2 4

som -1350- 1350
0 OPEN PIT
PONCE
LAJ 1400 1400 1400

2000 1900 1800 2100 1900 1900
-2
ON 2700 2300 2700 2800
-3 -
:6 -4 360 4000 3860
V
Lag 5500 12000 14000
-5 1100) 12500
-6 000 00 1200 12000
to
-7 11 00 13000
-8 6 0 1 1 - I - --- I I I I I
0 20 40 60 so 100 120 140 160 180 200

DISTANCE IN FEET

Figure 21--Specific conductance distribution for open pit in the Ponce
sand extraction area. 13000

EAST
Soo Soo Soo 50C
0
30C
500
500
-2

500 500
-3

-4
500 500
-5

-6
-7 500 500
-8 1 1 1 1 1 1 1 1
0 20 40 60 so 100 120 140 160 ISO

DISTANCE IN FEET

Flgure 22--Specific conductance distribution for open pit In the Aquada
sand extraction area.

WATER LEVELS

All test wells were measured for water levels on at least two
separate occasions. The first set of measurements was obtained
immediately upon completion of the drilling and development of the
wells. A second set of measurements was conducted on December 1-5,
1987 during a field reconnaissance with personnel of the P.R.
Department of Natural Resources.

Water levels were plotted on topographic maps (scale 1:20,000)
to delineate water-table contours and ground-water flow lines (figs.
23, 25, and 27). Cross sections were also constructed to describe
general hydrogeologic features of the sites (figs. 24, 26, and 28).

Sand extraction operations in Ponce apparently have caused a
distortion in the direction and movement of ground water at the site.
Flow lines near test well no. 5 appear to converge (fig. 23) to an
open-pit excavation that acts as a drainage feature to the local
ground-water system. Prior to the excavation, local flow lines in the
vicinity of the pit were generally parallel. The effects of the open
pit on the water-table surface can also be observed in the hydrogeo-
logic section shown in figure 24. The water level in the dune, near
test well 5, dropped about 3 feet as a result of the excavation pit.
This pit has locally increased the permeability in the aquifer and
acts as an open-evaporation reservoir which drains water from
the local ground-water system thus depressing the surrounding heads
in the aquifer.

In the Camuy sand-extraction site the configuration of the water-
table surface (fig. 25) apparently responds to the high permeability of
the backfill material. The test wells were drilled and developed in an
area which had been completely excavated and subsequently partially
backfilled with foreign material (limestone rubble and boulders). The
fill, with its corresponding structural arrangement making it relatively
permeable, replaced sand deposits apparently of lower permeability. As
a result of this backfilling with permeable material, surrounding heads
in the aquifer probably could have been depressed not only temporarely
but, also on a permanent basis. Although the regional pattern of ground-
water movement is northward, the flow lines in figure 25 suggest a loca-
lized movement slightly northwest toward the extraction zone. The aquifer
at this site exhibits a relatively flat water table (fig. 26) which is
typical of highly permeable zones. The hydrogeologic cross section shows
also the difference in elevations between the previous and existing land
surfaces.

Sand extraction operations in the Aguada site apparently have
caused changes in the hydrology of the area. Three existing hydro-
geologic features in the area seem to exert some control,to varying
degrees, in the hydraulics of the ground-water system;. (1) the
unextracted sand deposits' on the east that are of relatively

V-27

A).!kIA

1.1y
Tlp

.00 -01

3 3.0

(3.01)
60)_ ..0
N) 0.9
OD
. .... 50)

'104-
6 EXPLANATION
.69) LOCATION AND NUMBER OF
(1.50) NUMBEH IN PARENTHESIS
_VATION OF WATER-LEV
A
OVE MEAN f2A LEVEL
B

WATER-TABLE CONTOUR IN
ABOVE MEAN SEA LEVEL

GROUND WATER FLOW LINE
de his SoltIft.-;
CROSS SECTION A-A'

OPEN PIT

KI
0

Figure 23 Water-table configuration map In the Ponce sand-extraction site..

30 -
Ld

Ld
z z
:3
L W
z Ge
10 Lo 0
was x
0
pow
>
0
ID
49
ra WATER TABLE WATER TABLE
La (121V87) (7/20/"
z

z
0
BEACH DEPOSIT

-30 ......
1000 2000 3000 4000 5000
DISTANCE IN FEET

Figure 24--Hydrogeologic cross section A-A' along the Ponce sand-wctraction

flehuii do Ahwia

la Pcfloll

Na Puntilh
7

2.5 (3.8)
10

3.0

1,
01 k--
X

lip,

ff
CA) 11
0 Sov I
75

EXPLANATION
T4
7

K. -4
d, LOCATION AND NUMBER OF TEST WELL
(2.4) NUMBER IN PARENTHESIS INDICATES
ELEVATION OF WATER LEVEL ABOVE
MEAN SEA LEVEL

WATER TABLE CONTOUR IN FEET
ABOVE MEAN SEA LEVEL

GROUND WATERAOW LINE
CROSS SECTION A-A' J

OPEN PIT
IIt i`i(

Figure 25 Water-table configuration map In the Camuy sand-extraction site

At
30 00 (p C) (0 LAND SURFACE BEFORE
SAND-EXTRACTION OPERATIONS iz
0
20

z EXISTING
LAND
SURFA
-------------- -------------------------------------------
0

-10 SWAMP AND BLANKET SAND DEPOSIT
z WATER TABLE REPLACED BY FILL (LIMESTONE)
z (12/4/67)
0 -20

CAMUY FORMATION
Lid -30
0 200 400 goo Soo 1000 noo 1400 1600 1800
DISTANCE IN FEET

Figure 26--Hydrogeologic Cross Section A-A' In the Camuy sand-extraction s
_SURFA@CE@
..................

high permeability, (2) the limestone unit underneath Cibao Forma-
P4 tion) that is also very permeable, and (3) the backfilled material
apparently of relatively low permeability. The sand deposits seems to
be the most conspicuous hydrologic feature. Their high permeability
permits greater movement of ground water through this area causing the
flow lines to converge (fig. 27). Hydraulic gradients along these sand
deposits are relatively flat (fig. 28). On the other hand, the western
portion of the study area, where sand extraction operations have
occurred and the site backfilled with lower permeability material, is
characterized by steeper slopes and the existance of a localized water-
table mound. Flow lines in this particular area exhibits a pattern
of divergence (fig.27). Water levels in the dune apparently have not
been depressed by sand extraction operations (contrary to what occurred
in Ponce) as they still remain high (fig. 28). The water-table mound
described above probably has maintained the water levels from dropping
in the dune.

v- 32

3 6/, ........

14
RIO GRANT)F_1_, (8-0)
J

L
A

ot.
16

EXPLANATION

d LOCATION AND NUMBER OF TEST WELL
(5) NUMBER !N PARENTHESIS INDICATES
ELEVATICN OF WATER LEVEL ABOVE
MEAN SEA LEVEL

WATER TABLE CONTOUR IN FEET
S ABOVE MEAN SEA LEVEL
/o,
GROUND WATER F'_OW LINE

CROSS SECTION A-A'

OPEN PIT

0 .5
KILOMETER

Figure,27 Water-table configuration map in the Aguada sand-extraction site.

V_ 33

30
w
>
!I La
20 z
U)
Ix
10 0 OPEN PIT
0 U)
>
0
WATER TABLE

rk
-10 POSIT
z XCWA DEF --Iw ? CIBAO FORMATION
z ?
0 -20 ?
I W--@ ---*- -."
-30 ' ' ' I . I . .- . -1 -.
0 200 400 Goo Boo 1000 1200 "00 1600 1500 2000
DISTANCE IN FEET

Figure 28--Hydrogeologic cross section A-A' along the Aguada 3and-extractlo

Hydraulic Tests

"Slug injection" tests were performed at all 16 well sites
on Sept. 1-3, 1987 to determine relative hydraulic conductivities
and/or transmissivities of the formations near the screened area
of the wells.

The basic premise of the "slug method" as defined by Cooper,
et. al.(1967) in "Response of a Finite-Diameter Well to an Ins-
tantaneous Charge of Water" is: "In areas lacking either flowing
wells or wells equipped with pumps, it may be desireable to obtain
at least an estimate of the transmissivity of the aquifer by use
of the so-called "slug method". In this method a known volume or
"slug" of water is suddenly injected into or removed from a well
and the decline or recovery of water level is measured at repeated
intervals during the ensuingd minutes".

The equipment necessary to perform the tests is: 1) a calib-
rated bucket with a funnel tube on the bottom, 2) steel and elec-
tric measuring tapes, and 3) a pressure transducer coupled to a
micro-logger. The pressure transducer is a titanium alloy probe
connected to a 400 ft cable that reads water pressure above the
probe in pounds per square inch (PSI) and converts it to water
level in feet above the probe. This is connected to a portable
micro-logger that reads the signals from the transducer up to 30
times a second and displays the information in a time/water level
format. The micro-logger can be programmed to specific starting
water levels and ranges and measures changes in head to 0.01
inches.

At the beginning of a test, the probe is'placed to a speci-
fied depth below the surface of the water in the well and secured.
The static water level is then measured and noted. The calibrated
bucket is then filled with a certain quantity of water, usually 1
to 3 gallons. The bucket is then placed over the well with the
funnel tube inside the opening at the top of the well. At a prear-
ranged time, the micrologger is started and the plug pulled from
the bucket, allowing the water to fall "instantaneously" into the
well. The water level rises immediately and then starts to fall
as the water seeps into the formation. The micrologger reads the
changes in levels at specific intervals and converts them to a
semi-log cycle format. The "recovery" is plotted later as a
semi-log curve (Appendix A,B, and C) and serves as the basis for
the determination of transmissivity (T).

Water levels are monitored during the test and when they re-
turn to static conditions, the test is completed. The data from
each test is stored on a channel in the micro-logger and transfer-
red into the main United States Geological Survey computer.

v-35

H/Ho CURVE MATCHING METHOD
--------------------------

The basic transducer data is used along with a computer prog-
ram and a gra hics plotter to generate a semi-log graph of the re-
covery curve 9f each slug test. Due to the nearly vertical slope
of many of the curves, an extension of the type curves for values
2
of H/Ho and Tt/r=beta was developed from a table in an article by
Papadopulous,:et.al. (Aug.1963) titled, "On The Analysis Of Slug
Test Data" Water Resources Research p.1088,. The values for beta
-6 -8 . -10
are 10, 10, and 10. The time (t) point is determined using the
traditional matching curves method, except that the x-axis of both
curves are kept in line. Transmissivity (T) is derived using the
formula:

2
1.0(r
T w x 86,400 sec./day

Where r = the radius of the well in feet (4 inches)
w

t = time in seconds

V- 36

RESULTS OF HYDRAULIC TESTS AT WELLS IN
SAND EXTRACTION SITES AT PONCE, CAMUY AND AGUADA

The results of the slug tests are described in terms of hydraulic
conductivity (K) with units of feet per day (ft/d). Hydraulic
conductivity is defined as:

"A medium has a hydraulic conductivity of a unit length
(feet) per unit time (day) if it will transmit in unit
time a unit volume of ground water at the prevailing
viscosity through a cross section of unit area, mea-
sured at right angles to the direction of flow, under
a hydraulic gradiant of unit change in head through unit
length of flow."

There are many factors which affect the hydraulic conductivity
of a formation. Highly conductive materials such as sand, porous
limestone, shells, or gravel can be interbedded or intermixed with
clays, silt, or other marterials which will lower K. Compaction,
fractures, localized porosity, grain size, sorting and shape of sand
and/or gravel all influence hydraulic conductivity.

Computed hydraulic conductivities (K) for test wells 1 through 5
at Ponce ranged from 65 to 320 ft/d (Table 1 Figure 29 , Appendix A).
The wells with a lower K (test wells 1,3 and 4) are in fine to medium
sand and clayey sand. Test wells 2 and 5 have a higher K, 220 and 320
ft/d, respectively. The difference is due to coarse sand and shells
in the area, which are frequently associated with a higher conductivity
than clayey sand. Figure 29 delineates hydraulic conductivity contours
in the Ponce extraction site.

Test wells 6 through 11 at Camuy have hydraulic conductivities
ranging from 15 to greater than 320 ft/d ( Table 1, Figure 30,
Appendix B). These wells were drilled in loose, coarse sand to cemented
sandy material. As mentioned above, depending on the tightness, grain
size, etc., compaction and or fracturing of the cemented sands; K can
vary considerably. Test wells 7 and 11 have the lowest K (40 and 15ft/d,
respectively). Clay in test well 7 and the hard compacted nature of the
cemented sands in TW 11 contribute to the lower hydraulic conductivity.
Test well 10, with a K value of 105 ft/d, consists of hard silty sand,
more conductive than test wells 7 and 11 but is affected by its silty
nature. Test wells 6 and 8 both had higher K values (>320 ft/d).
Although the materials in which the wells were drilled consist of sand
and cemented sand, the disposition of sandy layers within the cemented
sand along with possible fractures, produce higher K values. Figure 30
delineates hydraulic conductivity contours in the Camuy site.

V-3 7

TABLE 1 HYDRAULIC CONDUCTIVITIES AT TEST WELLS IN SAND
EXTRACTION SITES AT PONCE, CAMUY AND AGUADA

-----------------------------------------------------------------------------

SCREEN TRANSMISSIVITY HYDRAULIC SCREEN INTERVAL
SITE DEPTH INTERVAL 2 CONDUCTIVITY MATERIAL
(ft) (ft) (ft/d) (ft /d)

-----------------------------------------------------------------------------
P 0 N C E
TW-1 12 7-12 340 65 MEDIUM SAND AND
GRAVEL TO FINE SAND

TW-2 9 4-9 1100 220 MEDIUM TO FINE
SANDS WITH SHELLS

TW-3 37 33-37 430 85 CLAYISH SAND

TW-4 9 4-9 360 70 FINE SAND

TW-5 10 5-10 1600 320 FINE-MEDIUM SAND TO
SHELLS,COARSE SAND

C A M U Y
TW-6 9 4-9 >1600 >320 EOLINITE-CEMENTED
SANDS

TW-7 8 3-5 200 40 SAND AND CLAY
CEMENTED SAND

TW-8 11.5 6.5-11.5 >1600 >320 SAND/CEMENTED SAND

TW-9 18 13-18 345 70 COARSE AND CEMENTED
SAND

TW-10 12 7-12 530 105 HARD SILTY SAND

TW-11 16 11-16 80 15 HARD CEMENTED SAND

A G U A D A
TW-12 33 28-33 35 7 SI'LTY SAND

TW-113 14 9-14 320 65 LIMESTONE AND
CEMENTED SANDS

TW-14 15 10-15 160 30 LIMESTONE

TW-15 11 6-11 775 150 MEDIUM GRAIN SAND

TW-16 23 18-23 >1600 >320 LIMESTONE WITH CLAY
-----------------------------------------------------------------------------

V-38

2
(220)

CA)
co
(70)

0
EXPLANATION
(32
LOCATION AND NUMBER OF
NU
(70) MBER IN PARENTHESIS W
HYDRAULIC CONDUCTIVITY IN
/,.:70--' HYDRAULIC CONDUCTIVITY
IN FEET PER DAY

OPEN PIT
de 1" S1! 1 It I I S

IL K I
0 .5

Figure 2a Hydraulic conductivity computed for test wells In the Ponce sand-extraction site.

It! I to I I d
4 k

I'Ll PU11111h 7 - -----
4320)

l
00
oo
0
10 1105
_61 200
1, (
f L

0-:>, tjtt,
T C,

d I

501", .7

..to
EXPLANATION

LOCATION A14D NUMBER OF TEST WELL
d 1 .1'. . I.I.
(40) NUMBER IN PARENTHESIS INDICATES
po
HYDRAULIC CONDUCTIVITY IN FEET PER
DAY
I/ :, .. -.
00 HYDRAULIC CONDUCTIVITY CONTOURS IN
FEEI PER DAY

CROSS SECTION A-A'
),j
OPEN PIT
01
7 1343 0)

10
10.
Zoo*

0 .6 1
KILOMETER

Figure 30 -Hydraulic conductivity computed for test wells In the Camuy sand-ext

The hydraulic conductivities of test wells 12 through 16 at Aguada
ranged from 35 to >320ft/d (Table 1, Figure 31, Appendix C). Test
well 12, with a K value of 7ft/d, consists of silty sand that limits
the flow of water. Test wells 13 and 14 with K values of 65 and 30 ft/d
are in limestone with varying amounts of clays or interbedded cemented
sands which influence K values. Test well 15, with a K of 150ft/d, is
composed of relatively pure medium-grained sands with little silt or
other materials to lower K values. Test well 16, with a K value of
>320 ft/d, has mostly pure porous limestone with some clay. The
porosity was not greatly affected by the clay, resulting in the higher
hydraulic conductivity. Figure 31 delineates hydraulic conductivity
contours in the Aguada site.

v- 41

(150) '200
Q i@o
2 ........
(65) (320)
14
DE
R, A N
I D i@ "V
P10 GKA
3 -ou

-1000, V

*40V

EXPLANATION

d LOCATION AND NUMBER OF TEST WELL
(30) NUMBER IN PARENTHESIS INDICATES
HYDRAULIC CONDUCTIVITY IN FEET PER
DAY

IYDRAIJLIC CONDUCTIVITY CONTOUR
IN FEET PER DAY

OPEN PIT

0 .5
KILOMETER

Figure 31 Hydraulic conductivity computed for test wells in the Aguada saAd-extraction site.

V-42

SUMMARY AND CONCLUSIONS

A total of sixteen test wells were drilled in sand-extraction
areas at Ponce, Camuy and Aguada. These were cased, screened, and
surveyed to mean sea level. The depth of wells ranged from 9 feet
to 37 feet. The lithology varied slightly among the three areas and
consisted mainly of combinations of sands, clays and/or'limestone.

Water quality samples were taken from the sixteen wells and two
open pits at Ponce and Aguada and analysed for specific conductance
and chlorides. Specific conductance from the wells varied from 340 to
50,000 usiemens/cm in Ponce, 340 to 2775 usiemens/cm in Camuy, and
370 to 37,500 usiemens/cm in Aguada. Chlorides ranged from a minimum
of 36 mg/l in a well at Aguada to a maximum of over 10,000 mg/l in
Ponce. Water samples from the open pits revealed a pronounced strati-
fication with depth of specific conductance at the pit in Ponce
(from 1400 to 14,000 usiemens/cm) and a uniform distribution (500
usiemens/cm) both areally and with depth in the pit at Aguada.

Water levels were measured twice during the period of study.
Water-table contour maps and cross sections were constructed to
describe ground-water flow patterns at the sites and how these could
have been affected by the sand-mining operations.

"Slug" injection tests were performed to determine hydraulic
conductivities at all well sites. The lowest value of 7 ft/d was found
at. Aguada in a silty sand matrix. Values of over 320 ft/d were found
in all three areas in sites containing sand deposits mixed with shells
or other highly permeable materials.

Open-pit mining of coastal sand deposits seems to locally affect
the ground-water hydrology of coastal zones. It can result in the
lowering of water levels at the dune area with the eventual migration
either inland or seaward of the freshwater-saltwater interface. The
extent to which this will occur depends on climatic and hydrogeologic
conditions of the area.

Backfill techniques to restore the site will not severely alter
the ground-water system, as long as the fill material has similar hy-
draulic properties as the original extracted sand. When local hydraulic
conductivities in the aquifer are significantly altered by mining ope-
rations, ground-water flow lines are distorted either temporarely
or permanently, depending on existing hydrogeologic conditions.

The open pit in Ponce, near test well 5 remains uncovered with
backfill material and has locally increased the aquifer permeability.
As a result, surrounding water levels in the aquifer and consequently
in the dune have dropped by as much as 3 feet.

V- 43

In the area of Camuy, the sand-extraction site has been partial-
ly backfilled with apparently high permeable material. As a result,
surrounding heads in the aquifer probably could have been depressed not
only temporarely but, perhaps also permanently.

In Aguada, sand mining operations appear to have caused local
changes in the hydrology of the site. The area where sand extractions
have occurred was backfilled with materials of lower permeability than
the original sand deposits. As a result, a water-table mound apparently
has been developed which seems to have inhibited a decline of water
levels in the adjacent dune. The mound could probably has also inhibi-
ted migration of seawater into the open pit.

V-44

APPENDIX A

Hydraulic Conductivities from Slug Tests
In Test Wells 1-5 at Ponce

V- 45

0.8

T I.Or

T 340 ft /d
0.

0
K 65 f t/d
Hill
0.4

0.2

0-
1 10 100 1000 10000 100000
T1 ME IN SECONDS
1i'T

HYDRAULIC CONDUCTIVITY FROM "SLUG" TEST
IN TEST WELL I AT PONCE

V- 46

0.8-

T 1.0r Vt

1I-T 1100 ft /d
0.6

j!
0
lj;K 220 f d

141
Iij
0.4--

110
0.2-

j:11

0
1 10 100 1000 10000 100000
TIME IN SECONDS
v

HYDRAULIC CONDUCTIVITY FROM "SLUG" TEST
IN TEST WELL 2 AT PONCE

V- 47

0.8
T
Q

'2
T I.Or /t

0.6 T 4310 f.,. 2/d
oi

0.4 `-K 8 5, f 0'

0.2
iol iiii

0
1 10 100 1000 10000 100000
TI ME IN SECO NDS

HYDRAULIC CONDUCTIVITY FROM "SLUG" TEST
IN TEST WELL 3 AT PONCE

V- 48

T 1.0r'/t

2/d
''IT 360 ft
0.6 tit
iki

70 f t1q

0.4

0.2

0 rrrrrf
1 10 100 1000 10000 100000
TIME IN SECONDS

HYDRAULIC CONDUCTIVITY FROM "SLUG" TEST
IN TEST WELL 4 AT PONCE

V- 49

0.8

IT 1.0r'/t

2/d'
T= 1600 ft
0.6-

@'K 329 f t/d I

0,4--

0.2
1

0 -
1 10 100 1000 10000 100000
TIME IN SECONDS
-L@4

HYDRAULIC CONDUCTIVITY FROM "SLUG" TEST
IN TEST WELL 5 AT PONCE

v- -15 0

APPENDIX B

Hydraulic Conductivities from Slug Tests
In Test Wells 6-11 at Camuy

V-51

0.8

2-
T 1.'0 r /t

ft2
0.6 :T +1600 /d

0
j,11K +3.20 f t/d

0.4

0-2

0
1 10 100 1000 10000 100000
TIME IN SECONDS

HYDRAULIC CONDUCTIVITY FROM "SLUG" TEST
IN TEST WELL 6 AT CAMUY

V- 52

10, 1 @d,
0.8
0,
01
ol 1.'0r2
/t
0
0
01
T 2'00 f tl-/d
0.6

0 j:
ic
'K 40 it@d
0:

0.4-

0. 2

-PAL
0
1 10 100 1000 10000 100000
TIME IN SECONDS

HYDRAULIC CONDUCTIVITY FROM "SLUG" TEST
IN TEST WELL 7 AT CAMUY

V- 53

oj
0.8

@!j 1

2/*
1.0r t

2
.4-T +16 00 ft /d
0.6

K 32
m: 0 il/d

0.4 -

0 .2

J:i

0
1 10 100 1000 10000 100000
TIME IN SECONDS

HYDRAULIC CONDUCTIVITY FROM "SLUG" TEST
IN TEST WELL 8 AT CAMUY

V- 54

q,
0.8

2
1.0r /t

2
0.6 T 345 ff /d

lid
K 70 f t/d

0.4 i 0

0.2

0 .7 r i
1 10 100 1000 10000 100000
TIME IN SECONDS

HYDRAULIC CONDUCTIVITY FROM "SLUG" TEST
IN TEST WELL 9 AT CAMUY

V- 55

(DOE)

01
oi

!T l.Cr'/t

2
0--. T 530 f t 1/d
0.6

lilt
105 ft

H
0.4

01
0.2--
) di

0 1
1 10 100 1 C 0 0 loccio 100cco
TIME IN SECONDS
Iwo
d

HYDRAULIC CONDuCTIVITY FROM "SLUG" TEST
IN TEST WELL 10 AT CAMUY

V- 56

0.8 -

2 A
T l.Or
06

0.6- L-T 80 ft /d

K 15 f t/d
Ns"

0.4 -

0 nT' -n I
1 10 100 1000 10000 100000
11ME IN SECONDS

HYDRAULIC CONDUCTIVITY FROM "SWG" TEST
IN TEST WELL 11 AT CAMUY

V- 57

APPENDIX C

Hydraulic Conductivities from Slug Tests

In Test Wells 12-16 at Aguada

V- 58

0.8-

2
0 T 1 0irt
0.6- (D T 35 ft

cl K 7 ft

0.4-

0.2-

0 Ll I I 1@@I I
sit r
1 10 100 1000 10000 100000
TIME IN SECONDS

HYDRAULIC CONDUCTIVITY FROM "SWG'* TEST
IN TEST WELL 12 AT AGUADA

V- 59

0.
T 1Or@l

0. 1 11 k I i I-IT 320 ft /d-

0
K

0. C)
-1

111.11 fill
0.2-

0-
1 10 100 1000 10000 100000
TIME IN SECONDS

HYDRAULIC CONDUCTIVITY FROM "SLUG" TEST
IN TEST WELL 13 AT AGUADA

V- 60

0.8

2 a
T I.Or

Ill. CD 11 1 1 IT 160 ft
0. /d

K 30

0.4

0.2-

0
1 10 100 "1060, 10000 100000
T
M S
IE IN ECONDS

HYDRAUUC CONDUCTIVITY FROM "SLUG" TEST
IN TEST WELL 14 AT AGUADA

v- 61

0. T 775 ft /d

0
I K 150 ft/,
3@:

0.4--

0.2-

0--
1 10 100 1000 10000 100000
TIME IN SECONDS

HYDRAUUC CONDUCTIVITY FROM "SLUG" TEST
IN TEST WELL 15 AT AGUADA
v- 62

0.8-

T I.OrA

T +1600 ft2/d
0.6

0
K +320 1.

0.4

0.2

0
1 10 100 1000 10000 100000
11ME IN SECONDS

HYDRAUUC CONDUCTIVITY FROM "SWG" TEST
IN TEST WELL 16 AT AGUADA

v- 63

APPENDIX VI:
0 GEOLOGIC AND SOIL NOMENCLATURE

124

GEOLOGIC NOMENCLATURE

*Qa- Quaternary Alluvium

*Qb- Quaternary Beach Deposits

*Qd- Quaternary Sand Dunes

*Qe- Quaternary Eolianite Deposits

*Qs- Quaternary Swamp Deposits

*Qbs- Quaternary Blanket Sand Deposits

*Tc- Tertiary Cibao Limestone

*Tcu- Tertiary Camuy Limestone

*Tp- Tertiary Ponce Limestone

Referred to in text

VI-1

SOIL NOMENCLATURE

CAMUY

*TP- Tropopsamments

HD- Hydraquents

*RlC- Rio Lajas Series, sand

ClE2- Colinas Series, clay loam

RsF- San German Series, gravelly clay loam

SgD- San GermAn Series, gravelly clay loam

EbB- Espinosa Series, sandy clay loam

EcC- Espinosa Series, clay

AmC- Almirante Series, clay

VeB- Vega Baja Series, silty clay

EbC- Espinosa Series, sandy clay loam

GeC- Guerrero Series, sandy clay

CID2- Colinas Series, clay loam

PONCE

EnC- Ensenada Series, gravelly clay

Ma- Machuelo Series, clay

Te- Teresa Series, clay

*Mr- Meros Series, sand

*Se- Serrano Series, sand

Hz- Hydraquents, saline

YcC- Yauco Series, silty clay loam

VI-2

SOIL NOMENCLATURE (Cont.)

AGUADA

Ch- Cidral Series, coastal beach sand

*Cd- Cataiio Series, sand

Sn- Santoni Series, clay

Ba- Bajura Series, clay

MaB- Mabi Series, clay

ClE- Colinas Series, clay loam

Nad- Naranjo Series, clay

Es- Espinal Series, sand

Cn- Coloso Series, silty clay loam

Referred to in text

VI-3

AihL

3 6668 14101 2551 ,