Ground-water protection report for Dorchester County

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

GROUND-WATER PROTECTION. REPORT
FOR DORCHESTER COUNTY

PREPARED FOR:

DORCHESTER COUNTY DEPARTMENT
OF PLANNING AND ZONING
DORCHESTER COUNTY DEPARTMENT OF HEALTH

JUNE 1988 COASTAL ZONE
INFORMATION CENTER

PREPARED BY:

GERAGHTY & MILLER, INC.
TD GROUND-WATER CONSULTANTS
426 ANNAPOLIS, MARYLAND
G76
1988

GROUND-WATER PROTECTION REPORT
FOR DORCHESTER COUNTY

PREPAF16ED FOR:

DORCHESTER COUNTY DEPARTMENT
OF PLANNING, AND ZONING
DORCHESTER COUNTY DEPARTMENT OF HEALTH

JUNE 1988

U - S - DEPARTMENT OF COMMERCE NOAA
COASTAL SERVICES CENTER
2234 SOUTH HOBSON AVENUE
CHARLESTON -SC 29405-24 13

PREPARED BY:

GERAGHTY Sk MILLER, INC.
GROUND-WATER CONSULTANTS
ANNAPOLIS, MARYLAND

troperty of CSC Library

ACKNOWLEDGEMENTS

The preparation of this report was funded under a grant
from the Maryland Department of Natural Resources, Coastal
Zone Management Program, with financial assistance provided
by the Coastal Zone Management Act of 1972, as amended,
administered by the Office of Ocean and Coastal Resource
Management, National Oceanic and Atmospheric Adminstration.

TABLE OF CONTENTS

PAGE

INTRODUCTION ........................................... 1

Report Preparation* ......................... 2

BACKGROUND INFORMATION ............................ 3

Contaminant Migration... .................... 3
Treatment Zone Concept ............... 6
Conditions for Relaxing Treatment
Zone Requirements ....................... 9
Current Practices .................. o ......... 9

MANAGEMENT STRATEGIES .........o........... oo ....... .. 11

Management Area Delineation ................... 11
Management Strategy: Area A ................. 14
Management Strategy: Area Bl ................ 18
Management Strategy: Area B2 ................ 20
Management Strategy: Area C ................. 22
Innovative and Experimental on-Site Sewage
Disposal Systems ........................ 25
variances .................................... 25

REFERENCES .............................. *... *......... 27

APPENDIX A: SUMMARY OF GROUND WATER CONDITIONS

APPENDIX B: INVENTORY OF NITRATE LEVELS IN GROUND-
WATER SAMPLES FROM DRINKING WATER WELLS

APPENDIX C: NITROGEN LOADING CALCULATIONS

APPENDIX D: HYDROGEOLOGIC GUIDELINES

APPENDIX E: STATUS REPORT ON INNOVATIVE AND ALTERNATIVE
@ON-SITE SEWAGE DISPOSAL PROGRAM

APPENDIX F: WELL DATA SHEETS

LIST OF FIGURES

1. Management Areas for Dorchester County ......... 13

2. Aquifer Use Areas for Dorchester County ........ 15

3. Generalized Geology of the Maryland Part of
the Delmarva Peninsula. (From Bachman, 1984 -
Adapted from Owens and Denny, 1979 and Owens
and Minard, 1979)... ..... ...... 0 ... A-7

4. Generalized Geologic Cross-Section for North-
east Dorchester County. (From Rasmussen and
Slaughter, 1957) ................. ............. A-9

LIST-OF' TABLES

1. Elimination constant and 99.9% Elimination of
Some Relevant Bacteria and Viruses in-Ground
Water (USEPA, 1987) .... *00 ....... 0 ............. 7

2. Management Strategy Area A ....... 40 ............ 16

3. Management Strategy Area B1 ..................... 19

4. Management Strategy Area B2 .................... 21

5. Management Strategy Area i@ a...0... 9.0 ... 24

6. Coastal Plain Stratigraphic Nomenclature and
Aquifers of the Eastern Shore of Maryland
(From Bachman, 1984) .......... 0............ A-6

7. Maryland Ground-Water Quality Standards. ........ A-14

8. Soil Profile Description of Ingleside Soil
Series with Silty Restrictive Unit at 56 to 72
Inches (Courtesy of USDA Soil Conservation
service ................................ A-17

LIST OF PLATES

Map Sheet 1. Well Log Locations

Map Sheet 2. Ground Water Management Areas

Map Sheet 3. Aquifer Use Areas

Map Sheet 4. Water Quality Data Point Locations

INTRODUCTION

The State of Maryland is committed to protect the physical,
chemical. and biological integrity of the (State's) ground-water
resources in order to protect human health and the environment. to
insure that an adequate supply of the resource is available and that
in all situations to manage that resource for the greatest beneficial
use of the citizens of the state.

Maryland Ground-Water Steering Committee

Ground water is an extremely valuable natural resource
to the citizens of Dorchester County. Ground water is the
sole source of drinking water and is essential for both
industry and agriculture. The protection of the Dorchester
County ground-water resources involves the control of many
potential sources of contamination such as underground
storage tanks, landfills, lagoons, and the subject -of this
report, on-si te wastewater disposal.

Maryland's regulations for on-site sanitary wastewater
disposal in areas where public. sewer systems are unavailable
were modified in 1985 to better account for the protection of
ground-water resourcesi. These regulations address the
siting and design of on-site sanitary wastewater disposal
systems. The principal mechanism for protecting ground-water
resources is the recognition of a 'treatment zone' to occur
beneath a septic system infiltration trench. The mandated
treatment zone consists of four feet of unsaturated, uncon-
solidated material sufficient to attenuate effluent below the
bottom of the on-site sewage disposal system prior to the
waters recharging the uppermost ground-water unit.

1 COMAR 10.17.02, entitled "sewage disposal systems for
homes and other establishments in the Counties of
Maryland where a public sewage system is not
available."

The 1985 regulations allow for on-site sanitary
wastewater disposal systems to be sited in areas where less
than four feet of treatment zone is present under specific
hydrogeologic conditions, providing a management plan to
protect ground-water resources is in.place. Such a reduction
in the treatment zone thickness is commonly referred to as
"ground-water penetration." The Dorchester County Commission
has chosen to allow such siting where these specific
conditions are met. This ground-water protection report
describes those areas in Dorchester County where such
conditions may likely occur and presents the proposed
management approach to protect the County's vital ground-
water resources in the context of on-site sanitary wastewater
disposal.

The intent of the ground-water protection reporting
effort in Dorchester County was to systematically assess
available ground-water resources, in order to develop water
supply and on-site sanitary wastewater disposal management
strategies appropriate to protect near surface ground-water
aquifers for their current and potential use as water
supplies. The management plan presented in this report
provides a tool for both the development community and public
health authorities to achieve needed on-site wastewater
disposal and water supply. The report reflects county-wide
differences in hydrogeologic conditions and accepted
sanitary wastewater disposal practices. The proposed
management practices were selected in order to meet State of
Maryland criteria and are considered to be protective of
groundwater resources.

Report Preparation

The preparation of the Dorchester County Ground-Water
Protection Report involved collecting information on existing
soil and hydrogeologic conditions, delineating management

areas on the basis of information collected, and developing
appropriate management strategies for each area.

Geraghty & Miller, Inc. (G&M) was responsible for
collecting information pertainin g to management Areas A and C
(see Figure 1). This information was included in a Phase I
report completed in July 1987. Information pertaining to
Area B was collected by the Maryland Department of the
Environment, Division of Residential Sanitation. Using the
information obtained,, G&M developed management strategy
options for each area. These options were used by the
Dorchester County Division of Environmental Health, in
conjunction with the Maryland Division of Residential
Sanitation, to develop a final, county-wide management plan.

BACK GROUND INFORMATION

contaminant migration

The contaminants of concern associated with on-site
sanitary wastewater disposal are bacteria, viruses and
certain inorganic compounds such as chloride, sulfate,
phosphate and primarily, nitrate. The soil is capable of
treating these contaminants to such a degree, providing the
proper conditions are met, that the water is of acceptable
quality for discharge to the groundwater (USEPA, 1980).
Attenuation mechanisms influenced by soil properties include
mechanical filtration, volatilization, dispersion, chemical
and biochemical alterations, oxidation-red uction, ion
exchange and biodegradation.

Soil media characteristics including grain size/
texture, porosity (primary and macro/secondary), and
permeability influence contaminant transport and both
mechanical and chemical attenuation processes. A longer path
length and contaminant travel time through the soil allows
for the maximization of attenuation processes.

In general, a smaller grain size provides more
mechanical filtration than a larger grain size. The decrease
in porosity and slower permeabilities of fine-grained
materials also increases contaminant travel times and thus
increases. the contact time of the contaminant with oxygen or
the surrounding media.

Oxidation/reduction reactions are controlled by the
presence of oxygen in the soil. media. Redox reactions may,
in some cases, help to attenuate certain contaminants by
decreasing their solubility. For example, some heavy metals
are prevented from leaching because of the formation of
insoluble metal oxides that result from oxidation. However,

other oxidation/reduction reactions produce highly soluble
salts that can be easily leached to the groundwater.

The oxidation of ammonium to nitrate is of particular
concern to on-site wastewater management. Nitrate is the
most common contaminant identified in groundwater and is
becoming increasingly widespread because of agricultural
activities and sewage disposal on and beneath the land
surface. Nitrate is the stable form of dissolved nitrogen in
the oxygen-rich groundwater environment and is not attenuated
to any significant degree (Freeze and Cherry, 1979).

The elimination of bacteria and viruses from the
wastewater results from the combined efforts of physical
(including temperature), biological, and chemical conditions.
Elimination is faster at high temperatures, at pH values of
about 71 at low concentrations, and at high levels of
dissolved carbon. These conditions activate natural bacteria
which act antagonistically towards the pathogenic
microorganisms in the waste material (USEPA, 1987). Virus
survival is controlled by the climate, clay content and
moisture-holding capacity of the soil. viruses are very
persistent and can migrate considerable vertical and
horizontal distances. In general, longer residence times in
the soil allow for natural die off to occur, thus diminishing
virus concentrations (USEPA, 1.987).

All of the above mentioned attenuation mechanisms
continue to occur in the saturated zone. They are, however,
less effective under saturated conditions (USEPA, 1987).
Thus a high water table diminishes the treatment capacity of
the soil by decreasing the unsaturated zone (USEPA, 1987).
The principal attenuation mechanism operating in the
saturated zone in dilution. Nitrate concentrations, in
particular, are controlled by dilution. Bacteria and virus
die off also continues to occur in the saturated zone (see

Table 1) Research appears to indicate, however, that
certain organisms can persist for longer periods of time in a
low temperature, oxygen-rich ground-water environment (USEPA,
1987).

Treatment Zone Concept

A combination of soil texture and permeability, in
combination with distance to the water table,, provides'the
basis for the treatment zone concept employed to treat waste
water from on-site disposal systems. The bulk of available
data and research indicates that a two- to four-foot depth of
suitablef unsaturated soil material will provide a high
degree of treatment of septic tank effluent. It has been
reported that such a treatment zone provides that almost
complete removal of Chemical oxygen Demand, (COD), Biological
Oxygen Demand (BOD), suspended solids, and phosphorus and
significant removal of bacterial contaminants can be achiev-
ed. Data to support similar reduction of viruses are not as
conclusive.

other chemical constituents, such as nitrogen, exchange-
able cations, chloride, sulfates, sulfides, other anions and
trace organics, undergo various reactions in the soil treat-
ment zone and may be attenuated to different degrees. Many
of these chemical constituents are not attenuated to any
great extent and over time will move downward with soil
waters and mix with underlying ground waters. Increases in
total dissolved solids, chlorides and nitrate-nitrogen of
ground waters may be experienced. The significance of these
impacts and the resulting degradation of ground-water quality
becomes more important as densities of on-site wastewater
disposal systems increase. Cumulative effects of impacts
from on-site wastewater disposal systems, and other sources
of contaminants associated with -suburban land use, have

99.9% Elimination or I I a,
in Water After 27S ; 710 A 23 16 14 12 10 9
140 1 1
50 Days 10 Dirs
Shigells Lp. Coliform bacteria

Salmonella faecalis

E. coli
;4ean of Evaluareo, Investigarions

More Persistent than E. coli a Less Persistent than E. coli

S. typhi

Viruses (Polio.. Hepatitiv. Entero-)

S. pararyphi

S. Typh;rnuriurn

Elimination I a I- - 4-
Constant (1/day) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 O-E 0.9 1.0

SOURCE. *A-%,tk *1 0, 198S

Table 1. Elimination Constant and 99.9% Elimination of Some
Relevant Bacteria and Viruses in Ground Water.
(USEPA, 1987)

produced significant ground-water pollution in some areas
along the Atlantic coast.

The depth of unsaturated soil material below the bottom
of on-site systems that is needed for adequate treatment is
primarily dependent on site-specific soil properties. soil
properties, such as clay content and mineralogy, percent of
rock fragments, and permeability, will have the greatest
effect on the degree of treatment of septic tank effluent.
Generally, soils with rapid. permeabilities may require
greater unsaturated depths than soils with slow permeability
to achieve the same level of treatment. In some instances of
rapid and very rapid permeabilities, even four feet will not
provide adequate treatment. It is generally recognized that
two to four feet of unsaturated soil provides effective
treatment.

With the 1985 regulations, the State has adopted a four-
foot treatment zone, not only to provide a high degree of
treatment, but for two additional, practical reasons. These
reasons involve 1) the difficulty of estimating accurately
depth to the seasonal high water table based on minimal
observations, and 2) typical installation problems that often
result in actual treatment zone depths being less than design
depths. Use of a four-foot treatment zone allows for a
reasonable margin of safety when considering the practical
limitations of evaluating sites and installing systems.

The presence of an unsaturated soil treatment zone will
not provide complete treatment: of all constituents in septic
system effluent waters. Some alteration of ground-water
quality in the vicinity of the infiltration field will occur
regardless of thickness and soil properties of the treatment
zone. While the majority of pathogens and particulate will
be removed, various species of nitrogen (particularly
nitrates) and inorganic ions such as chlorides will not be

significantly removed. For this reason, other management
practices, in addition to the treatment zone requirement
(i.e., density controls, and well construction controls), may
be necessary to more fully protect ground waters that serve
as sources of drinking water.

Conditions for Relaxing Treatment Zone Reauirement

Maryland Health regulations allow for the use of on-site
sanitary wastewater disposal systems with less than four feet
of treatment zone if
a) The receiving aquifer had been designated as Type III
(other than Type I or Type II) , pursuant to COMAR
10.50.01; or

b) The receiving aquifer has limited potential to serve
as a drinking-water source. Criteria for determining
that an aquifer has a limited potential to serve as a
drinking-water source are:

i) Provision of insufficient potable water to
serve as a year-round supply due to seasonally
fluctuating water tables,

ii) Interconnect ion with tidewater such that if
pumped for water supply, brackish water or
saltwater intrusion into the aquifer has or would
occur,

iii) Depth to ground water would preclude on-site
wastewater disposal except by ground-water
penetration and there is evidence the aquifer has
already been polluted by, or is in imminent danger
of being polluted, by, agricultural or other
potentially polluting activities in the area.

Current Management Practices

Many areas within Dorchester County have a seasonally
high water table at depths that cannot provide the' four-foot
treatment zone. Previous regulations have allowed Dorchester
county, along with Talbot, Wicomico, Somerset, and Worchester
Counties, to discharge septic-tank effluent directly into
shallow aquifers under the following conditions:

1. Areas of utilization should be confined to those
portions of each county where surface soil formations
consist of a thick layer of impermeable clay
underlain with extensive deposits of water-bearing
sand.

2. A minimum separation distance of 150 feet should be
maintained between any individual water supply and
sewage disposal facilities.

3. Maximum density of housing in these areas should not
exceed 160 residences per square mile.

4. Systems are to be empirically sized based on county
experience.

5. Wells for potable water supply utilizing shallow
aquifers .-may not be permitted if on-site systems
discharge directly to ground water.

This practice has been referred to as ground-water
penetration and is used routinely in these counties on necks,
peninsulas and islands.

other coastal plain counties, while prohibited by
regulation from using ground-water penetration, have utilized
treatment zones that vary from less than one to greater than
four feet. Several of these counties have been granted
variances to allow ground-water penetration. In addition,
many counties have had to resort to ground-water penetration
occasionally to remodel failing on-site systems when no other
conventional alternative was available.

Local county health departments that routinely use
ground water penetration have not associated any major public
health problems with these systems. Extensive monitoring and
well-documented studies of the impact of these systems on
ground water or surface waters, however, have not been
conducted.

MANAGEMENT' STRATEGIES

Management Area Delineation

Management area evaluation and delineation was made on
the basis of hydrogeologic conditions and existing aquifer
water quality and use patterns. Hydrogeologic conditions
considered included the presence of confining layers and
existing soil conditions. The presence of a confining layer
between the waste disposal system and the water supply
aquifer can act to inhibit or prevent downward migration of
contaminants. In, cases where there is no confining unit,
soil conditions become more important in management area
delineation. The thickness and type of soils present in the
unsaturated zone controls, primarily, the.degree of treatment
provided to the wastewater. A thick unsaturated zone with
fine-grained soils (loamy texture) provides better treatment
than one that.is less deep or has sandy soils.

Aquifer water quality and use patterns were also
considered when delineating management areas. Stringent
protection must be provided to those areas where the
uppermost unconfined aquifer is being used as a water supply
source. Less stringent protection may be applied to those
areas where the uppermost aquifer is of poor quality, or
where there is a deeper, confined aquifer of sufficient
quality and yield to be a drinking water source.

Pertinent existing hydrogeologic information was
compiled to determine the presence of shallow confining
units, determine ground-water quality in the surficial
aquifer, examine ground water use for drinking water, and to
determine, in general, soil types and depth to the water
table. Map Sheet 1 shows the location of well logs that were
used to assess ground water conditions in Dorchester County.

See Appendix A for a detailed discussion on investigation
methods and information obtained from the study.

Three management areas were identified as shown in
Figure 1 and Map Sheet 2. Area A can be characterized as
having little or no shallow confining material and is subject
to maximum protection of the near surface water-supply
aquifer. Area B includes those areas where more than 5 feet
of shallow confining material separates shallow permeable
layers used for disposal of sewage effluent from deeper
water-supply. Area B appears to require less stringent
protection than Area A. Area C encompasses a portion of the
county for which insufficient data are available to map an
areally extensive shallow confining unit of at least 5 feet
in thickness. An interim management strategy has, therefore,
been developed until sufficient data is obtained. It is
anticipated that Area C will eventually be reclassified as

Area B.

Area B has been subdivided into two subareas: Area B2
in the southwestern part of the County where ground-water
elevations are commonly near ground surface and septic
systems may penetrate ground water year-round, and Area Bl in
the northwestern part of the County bordering the Choptank
River where septic systems may have a reduced treatment zone,
and will likely penetrate ground water only on a seasonal
rather than year-round basis.

It should be stressed that areas outlined on the map in
Figure 1 are generalized and based on limited data in some
places. Within each management area there may be localized
areas which require reclassification when additional data
becomes available. The distribution of the management areas
will be discussed in greater detail subsequently.

Federalsbu
AREA BI -AREA A
Cambridge Hurlock

ienna

AREA C

Imckgo
AREA B2@ Pbnd

FIGURE 1.

MANAGEMENT AREAS FOR DORCHESTER COUNTY

:1.3

A management strategy, based on the likelihood of
ground-water contamination due to on-site waste disposal
systems, has been developed for each of the four management,
areas. This strategy seeks to combine knowledge of existing
hydrogeologic conditions, available treatment zone geometries
and aquifer use and quality information with certain
management practices to insure that existing and potential
water supplies are fully protected. Management practices
include consideration of land development densities, well
construction practices, on-site waste disposal methods, and
site investigation requirements.

Management Strategy: Area A

Management Area A is outlined on Figure 1. It is
comprised of the northeastern portion of the County.which is
underlain by thick, permeable sands and gravels of the Kent
Island, Beaverdam Sand and Pensauken Formations. Few areally
extensive confining units are found at shallow depth (i.e.,
within 251 of ground surface) across Area A. These
formations currently provide water supplies and have future
water supply potential (see Figure 2), but have limited near-
surface confining material to provide protection of the
aquifer from near-surface sources of contamination.

To protect the existing and potential water supplies
available from shallow aquifers in Area A, sewage disposal
practices which maximize effluent treatment should be
employed. Table 2 presents on-site sewage disposal and water
supply options which are appropriate 'to provide the required
protection. The most ai plicable technology must be
determined through on-site evaluation of each site (including
soil, topography, and drainage characteristics). A reduction
of the minimum four-foot soil treatment zone can be allowed
where finer soil textures or fill materials along with in-
situ soils can provide adequate sewage effluent renovation

PLEISTOCENE?
CHOPTANK Federalsbu
a
PINEY POINT AREA A
AREA BI
Hurlock
Cambridge
PLEISTOCENE
a
CHOPTANK

ienna

AQUIA
J
AREA C
PINEY POINT
.4
k9c CHOPTANK
Pond
AREA B2 __j

NO DA TA

FIGURE 2.

AQUIFER USE AREAS FOR DORCHESTER COUNTY

TABLE 2. MANAGEMENT STRATEGY AREA A

Unsaturated Natural Soil SEWAGE DISPOSAL OPTIONS
Thickness Beneath Bottom AND REQUIREMENTS Minimum Separation
of Sewage Disposal Minimum Lot Distance: Wells L Minimum
Trenches Soil Texture Size Conventional Alternative Aquifer Type SDS/SRA Minimum Depth Grouting Depth

1. > 41 All Based on Gravity trench Shallow Unconfined 100, 50' Top of Screen
zoning Pressure Dosing
COMAR Trench Confined 50' N/A COMAR 10.17.13
10.17.02 Requirements
10.17.03
requirements

2. 2' - 4' All Based on Sand Mound Unconfined 100, 50' Top of Screen
zoning
COMAR Confined NIA COMAR 10.17.13
10.17.02 Requirements
10.17.03
Requirements

3. 2' - 4' Sandy Loam or 2 acres Gravity trench Shallow Unconfined 100, 50' Top of Screen
Finer Pressure Dosing
Trench (a) Confined N/A COMAR 10.17.13
Requirements

(a) At grade sand mounds may be utilized provided all other requirements are met.

for most wastewater constituents of concern (e.g.,
microorganisms, organic matter, solids, and phosphorus).
Protection of valuable surficial aquifers from nitrogen
pollution is provided by controlling on-site system density
with minimum lot sizes. Minimum lot sizes of two acres
provides a mechanism for dilution which should help ensure
ground-water levels of N03-N will remain at or below 10 mg/l
where this level is not already exceeded (see Appendix C for
nitrogen dilution calculations).

Sewage disposal trenches should always be installed to
maximize the soil treatment zone (i.e., as shallow as
possible) utilizing above-grade fill, if necessary. At grade
sand mounds may be utilized provided all other requirements
are met. The thicker the treatment zone utilized, the better
the sewage effluent renovation derived.

A minimum well depth of 50 feet is recommended to
provide protection against nitrate pollution from surface
sources in the recent past. Additional protection should be
afforded to wells in Area A by requiring well construction in
the unconfined aquifers to include grouting to the top of the
screen. Grouting should be completed from the top of the
screen up to the surface, using a tremie pipe to insure that.
a complete seal is obtained.

In areas such as Area A, in which there are valuable
surficial ground-water supplies, care should be taken to
eliminate introduction of household chemicals (e.g.,
solvents, degreasers, pesticides, etc.) into the ground
through septic systems. Homeowners should be informed of the
risks to sewage disposal systems and to water supplies, in
particular their own, from such activities and appropriate
alternative disposal options.

1.7

Management Strategy: Area Bl

Management Area Bl is outlined on Figure 1. It is
comprised of a small portion of Dorthester County which lies
just to the west of Management Area A bordering the Choptank
River. It is underlain by dip-posits of the Kent Island
Formation lying atop older Miocene sediments of the
Chesapeake Group. Confining beds in the Kent Island
Formation may seasonally perch ground-water which cannot
provide year-round water supplies. Confining material within
a 25-foot depth below ground surface provides for protection
of-the underlying Miocene water-supply aquifers.

Table 3 presents on-site sewage disposal and water
pply options which are appropriate for the hydrogeologic
conditions prevalent in Area Bl. These options allow for
su

direct penetration of shallow ground water which may often be
of a seasonal nature. Given proper well construction
requirements, existing and potential water supply resources
available in the underlying confining aquifers should be
adequately protected.

As in Area A, soil treatment zone thickness should be
maximized to reduce pollutant impacts on surface waters from.
shallow ground-water discharges and to optimize system
hydraulic performance. Minimum lot sizes of two acres are
set in order to achieve dilution where less than 4 f eet of
unsaturated soil treatment zone is employed (see Appendix C
for nitrogen dilution calculations). Again, the most
applicable disposal technology within the options given must
be determined from site-specif ic characteristics assessed in
a field evaluation.

Well construction practices shall preclude the use of
unconfined aquifers and require wells to be grouted through
the disposal stratum to the top of the screened interval

1.8

TABLE 3. MANAGEMENT STRATEGY AREA B1

Unsaturated Natural Soil SEWAGE DISPOSAL OPTIONS
Thickness Beneath Bottom AND REQUIREMENTS Minimum Separation
of Sewage Disposal Minimum Lot Distance: Wells Minimum
Trenches Soil Texture Size Conventional Alternative Aquifer Type SDS/SRA Minimum Depth Grouting Depth

1. > 41 All Based on Gravity trench Shallow
zoning Pressure Dosing
COMAR Trench Confined 100, N/A Top of Screen
10.17.02
10.17.03
requirements

2. 2' - 4' All Based on Sand Mound Confined 100, N/A Top of Screen
zoning
COMAR
10.17.02
10.17.03
Requirements

3. V - 4' All 2 acres Gravity trench Shallow
Pressure Dosing
Trench (a) Confined 100, N/A Top of Screen

4. 0' All 2 acres Sand Lined
Trench Confined 150' N/A Top of Screen

(a) At grade sand mounds may be utilized provided all other requirements are met.

using a tremie pipe. The well driller shall inf orm. the
Dorchester County Health Department prior to the grouting of
wells constructed in Area B1 such that they may send a
representative to inspect the grouting operation. The Health
Department has set, as a minimum goal, the inspection of 10%
of all wells constructed in Management Area Bl. A record of
inspection shall be maintained for their f iles. A minimum
separation distance of 100 feet shall be maintained between
any sewage disposal or reserve wastewater area and any water
supply wells where an unsaturated soil treatment zone of 1 to
4 feet in thickness is employed. A minimum separation
distance of 1501 shall be maintained between any sewage
disposal or reserve area and any water supply well where
direct ground-water penetration will occur.

Management Strategy: Area B2

Management Area B2 is outlined on Figure 1. It is
comprised of the southwestern portion of Dorchester County.
It is characterized by areally extensive surficial confining
beds of the Kent Island Formation which protect the
underlying confined aquifers from the downward movement of
surface and near-surface contaminants. Water supplies in
Area B2 are derived principally from confined aquifer wells
in the Piney Point and the Aquia formations (see Figure 2).

Table 4 outlines on-site sewage disposal system and
water supply options which are appropriate for the
hydrogeologic conditions prevalent in Area B2. These options
allow for direct penetration of shallow ground water which,
given proper well construction requirements, should protect
existing and potential water supply resources available in
the underlying confined aquifers. Large areas of poorly
drained and slowly permeable soils, such as the Othello
series, predominate in Area B2 and indicate the most likely
option to be employed, as it has in the past, will be direct

TABLE 4. MANAGEMENT STRATEGY AREA B2

1. > 4' All Based on Gravity trench Shallow
zoning Pressure Dosing
COMAR Trench Confined 100, N/A Top of Screen
10.17.02
10.17.03
requirements

2. 2' - 4' All Based on Sand Mound Confined 100, N/A Top of Screen
zoning
COMAR
10.17.02
10.17.03
Requirements

3. l' 4' All 2 acres Gravity trench Shallow
Pressure Dosing
Trench (a) Confined 100, N/A Top of Screen

4. 0 All 2 acres Sand-Lined
Trench Confined 150' N/A Top of Screen

All 4 acres for
5. 0' Parcel of Record
5 acres in a
subdivision bermed infiltration Confined 150' N/A Top of Screen
ponds

(a) At grade sand mounds may be utilized provided all other requirements are met.

ground-water penetration. However, where surface soils are
better drained and more permeable, wastewater disposal
systems employing an unsaturated soil treatment zone should
be utilized as the favored alternative given reasonable
indication of satisfactory hydraulic performance. Minimum
lot sizes are required to provide dilution and filtration to
minimize degradation of ground and surface water resources
(see Appendix C for nitrogen dilution calculations).

As in Area Bl, well construction practices shall
preclude the use of unconfined aquifers and require wells to
be grouted through the disposal stratum to the top of the
screened interval using a tremie, pipe. Well drillers shall
inform the Dorchester County Health Department prior to
grouting. The County has set', as a minimum goal, the
inspection of 10% of all wells constructed in Area B2. A
record of inspection shall be maintained for their files.

A minimum separation distance of 1001 will be required
between water supply wells and sewage disposal systems and
reserve areas employing an unsaturated soil treatment zone.
A minimum separation distance of 1501 will be required
between water supply wells and sewage disposal systems and
reserve areas utilizing direct ground-water penetration.

Management Strategy: Area C

Management Area C is outlined on Figure 1. It is
comprised of the southeastern portion of Dorchester County.
It is underlain by deposits of the Kent Island Formation
lying atop the sands and gravels of the Beaverdam Sand and
Pensauken Formations. Inadequat,e data exist for Management
Area C to characterize the areal extent of near-surface
confining beds and their thickness. Existing well records
indicate water supplies are derived primarily from deep
confined aquifers such as the Piney Point (see Figure 2).

2:2

The exception is Elliott Island., where shallow driven wells
tap the unconfined Parsonburg Sand atop the Kent Island
Formation. Hydrogeologic studies required for major
subdivisions (5 lots or more) and physical logging of near
surface sediments by the Environmental Health Division,
Dorchester County Health Department, for new water supply
wells should augment existing data sufficiently to allow an
eventual reclassification of Area C as either a Management
Area A or B; the latter being most likely.

Table 5 outlines on-site wastewater disposal system and
water supply options appropriate to protect existing and
potential water supply resources until further data can be
collected.

Soil treatment zone thickness should be maximized to
reduce pollutant impacts on surface and ground waters and to
optimize system hydraulic performance. A minimum one-foot
thick unsaturated soil treatment zone will be required.
Minimum lot sizes of 2 acres are required where a treatment
zone of less than 4 feet is utilized in order to provide
dilution and filtration to minimize degradation of ground and
surface water resources (see Appendix C for nitrogen dilution
calculations).

Well construction practices shall preclude future use of
unconfined aquifers and require wells to be grouted through
the disposal stratum to the top of the screened interval
using a tremie line. Well drillers shall inform the
Environmental Health Division, Dorchester County Health
Department, prior to installing new wells and grouting, to
allow County personnel to physically log near-surface
sediments 'during drilling and inspect grouting. The
Environmental Health Division, Dorchester County Health
Department, has set as a minimum goal the inspection of 10%
of new well construction grouting. A record of inspection

TABLE 5. MANAGEMENT STRATEGY: AREA C

1. > 4' All Based on Gravity trench Shallow -
zoning & Pressure Dosing
COMAR Trench Confined 100, NIA Top of Screen
10.17.02
10.17.03
requirements

2. 2' 4' All Based on Sand Mound Confined 100, N/A Top of Screen
zoning
COMAR
10.17.02 &
10.17.03
Requirements

3. b,c 1 - 4' All 2 acres Gravity trench Shallow
Pressure Dosing Confined 100, NIA Top of Screen
Trench (a)

(a) At grade sand mounds may be utilized provided all other requirements are met.

(b) The sanitarian assigned to evaluate the applicant's lot shall determine if adjacent properties have shallow wells likely to be in the same stratum that is to
receive the sewage effluent. If the adjacent property has a shallow well, a 200 ft. separation between shallow welll and septic system is required.

(c) An alternative to the 200 ft. separation is to require the applicant to replace the neighboring shallow well with a deeper well screened in a confined aquifer.

shall be retained for their files. A minimum separation
distance of 1001 will be required between water supply wells
and sewage disposal systems and reserve areas.

Innovative and EXRerimental On-Site Sewage Disiposal Systems

The State Department of the Environment has an effective
program to develop innovative/alternative on-site sewage
disposal systems. Although the experimental systems are not
listed in Tables 2 through 5, their use where site conditions
warrant and County personnel are available for site
evaluation and monitoring is encouraged. Systems which are
considered experimental will change with time as the
successful systems become conventional and the unsuccessful
systems are no longer used. Appendix E, Status Report to the
Governor and General Assembly on the State of Maryland
Innovative and Alternative On--Site Sewage Disposal Progra ,
dated February 1987, will provide an overview of the State's
program and descriptions of the innovative and alternative
s
ystems with which the State is working. This should prove
seful in describing the alternative systems listed in Tables
2 through 5 as well as providing an understanding of the
experimental systems being developed.

Variances

One goal of adopting a county-wide ground-water
protection strategy is to employ a comprehensive rather than
a piecemeal approach to ground-water resource management.
Therefore, it is prudent to minimize small scale variance to
the broad management areas mapped. However, as previously
noted, management area boundaries are necessarily imprecise
and should be subject to revision as additional data warrant.
Decisions on management area placement for properties located
along area boundaries will be made at the discretion of the
Environmental Health Division, Dorchester county Health

Department, and supported by site-specif ic f ield data.
Applicants who disagree with this determination in management
fringe areas have the opportunity to provide site-specif ic
hydrogeologic information to support a more appropriate
determination.

Inclusions of one management area within the confines of
another will be restricted to areas in which the total
ground-water flow pattern can be adequately characterized and
supports the altered area designation. Appendix D provides
guidance for conducting hydrogeologic evaluations to support
management area determinations and subdivision requests
requiring detailed hydrogeologic information.

REFERENCES

Bachman, L.J., 1984. Nitrate in the Columbia Aquifer,
Central Delmarva Peninsula, Maryland. U. S. Geological
Survey, Water Resources Investigations Report 84-4322,
Towson, Maryland.

Bachman, L.J. and J.M. Wilson, 1984. The Columbia Aquifer of
the Eastern Shore of Maryland. Maryland Geological
Survey, Report of Investigations #40, Towson, Maryland.

Freeze, R.A. and J.A. Cherry, 1979, Ground Water, Prentice-
Hall, Inc., Englewood Cliffs, New Jersey 07632.

Mack, F.K., W.E. Webb, and R.A. Gardner, 1971. Water
Resources of Dorchester and Talbott Counties, Maryland.
Maryland Geological Survey, Report of Investigations
#17, Towson, Maryland.

Matthews, E.D., 1963. Soil Survey of Dorchester County,
Maryland. U.S.D.A. Soil Conservation Service. U.S.
Government Printing Office, Washington, D.C.

Owens, J.P. and C.S. Denny, 1979. Upper Cenozoic Deposits of
the Central Delmarva Peninsula, Maryland and Delaware.
U.S. Geological Survey, Professional Paper 1067-A. U.S.
Government Printing Office, Washington, D.C.

Owens, J.P. and C.S. Denny, 1986. Geologic Map of Dorchester
County. Maryland Geologic Survey, Towson, Maryland.

Rassmussen, W.C. and T.H. Slaughter, 1957. The Water
Resources of Caroline, Dorchester and Talbot Counties.
Maryland Geological Survey Bulletin 18, Baltimore,
Maryland.

Woll, R.S., 1978. Maryland Groundwater Information, Chemical
Quality Data. Maryland Geological Survey, Basic Data
Report #10, Towson, Maryland.

U.S. Environmental Protection Agency, 1980, Design manual:
Onsite wastewater treatment and Disposal Systems.
Office of Research and Development, Municipal
Environmental Reasearch Laboratory, Cincinnati, Ohio.

U.S. Enviromental Protection Agency, 1987, Guidelines for
Delineation of Well Head Protection Areas, Office of
Ground-Water Protection, 'Washington, D.C.

I
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APPENDIX A
I SUMMARY OF GROUND WATER CONDITIONS
I
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APREITDIX A

SUMMARY OF GROUND WATER CONDITIONS

Methods of Investigation

Pertinent existing hydrogeologic information was
compiled to determine the presence of shallow confining
units, determine ground-water quality in the surficial
aquifer, and to examine ground-water use for drinking water
within the study area. These criteria were used to concisely
determine the areas where a less than four-f eet treatment
zone may be allowed and to establish appropriate management
practices to protect ground-water quality and underground
drinking water sources.

Information and data relating to each delineation
criteria were collected by the Maryland Department of
Environment, Division of Residential Sanitation (Areas B1 and
B2) and by Geraghty & Miller, Inc. (Areas A and C) . The
following is a discussion of each criteria and the methods
and references used to obtain pertinent information.

Shallow/Confining Unit

In order to determine, generally, the presence of any
confining units within 25 to 50 feet of land surface in the
study area, lithologic descriptions from well logs were
examined. Geologic logs published by the Maryland Geological
Survey and the U.S. Geological Survey were considered primary
sources of information (Mack. et al, 1971; Rasmussen and
Slaughter, 1957; Wilson, 1984). A search for lithologic data
was conducted in the records of the Dorchester County Health
Department, where copies of all well permits, and well
completion reports including water well driller logs, are

A - 1

f iled. Over 1000 logs were. reviewed. Approximately 50
percent of the water well driller logs were unusable due to
incompleteness or difficulties in interpretation. Water well
driller logs are not expected to provide detailed
descriptions of lithology,, but were considered reliable as
general indicators of geologic conditions. The log
descriptions are made based on cuttings in the drilling mud,
not on representative samples taken from discrete depth
intervals. Thin confining units are very difficult to detect
from drilling cuttings.

The collected logs were recorded on Well Data Sheets
along with other information, such as the results of water-
quality analysis. The log data sheets are found in Appendix
F. Each log data point was then plotted on a County map (see
Map Sheet 1) and the depths to the f irst clay or silt units
were noted where such information was available. Areas
likely to be underlain by a continuous confining unit within
approximately 25 feet of land surface were identified when a
confining layer of at least five-feet thickness was indicated
consistently at approximately the same elevation (within 10
feet) in at least ten contiguous logs.

Water Ouality

Water-quality data for the surficial unconfined aquifer
in the study area were assembled from two sources. Basic
data report No. 10 of The Maryland Geological Survey,
Maryland Ground-Water Information: Chemical Ouality Data
(Woll, 1978) summarizes previously published shallow-aquifer,
water-quality data at a small number of sites in the study
area. Additionally, Dorchester County Health Department
water-quality data for domestic supply wells was used. Given
the objective to characterize the chemical quality of water
from the surficial unconfined aquifer, data was accepted only

A -- 2

if the depth or screened interval of the sampled well was
recorded. No data from wells of 1.00-feet depth or greater
were accepted and only data from those wells greater than 25
feet deep with an accompanying log showing no confining units
above the screened interval were accepted. Data from all
drive-point wells, which were assumed to be in the water-
table aquifer, were accepted.

Nitrate concentration levels were the most frequently
reported chemical-quality indicators. other parameters
occasionally recorded in the Dorchester County files included
pH, iron, fluoride, chloride, hardness (as CaC03), ammonia,
and total solids. Nitrate level, by far the most numerous
data, was chosen as a general -indicator of shallow ground-
water quality in the study area.

Nitrate concentrations are reported in milligrams per
liter (mg/1) of elemental nitrogen. Nitrate concentrations
can also be reported as mg/l of N03, a value 4.5 times
greater than a elemental nitrogen value because the three
oxygen atoms are included in the weight. The nitrogen
content of fertilizer is also routinely reported as elemental
nitrogen. The nitrate concentration at each data point was
plotted on a county-wide map and areas of apparent elevated
nitrate levels (i.e.,. greater than 5 mg/l in at least 10
contiguous data points) were generally delineated. Map Sheet
4 shows the location of water quality data points as well as
areas of elevated nitrate concentrations. Note that this map
was taken from the Phase 1 report and does not reflect recent
refinements of the management area boundaries. Also note
that no data was available for shallow ground waters in Area
B. Elevated levels of nitrate (i.e., concentrations above 3
to 5 mg/1) can be generally associated with human activities
resulting in reduced ground-water quality conditions.

A -- 3

Ground-Water Use for Drin ing water

Well completion records submitted to the State of
Maryland were used to determine the drinking water use of
various aquifers in the study area. The State of Maryland
Department of Health and Mental Hygiene provided a computer
printout of information on all well permits, i.e., well depth
and screened intervals, by Maryland grid coordinates. This
information was examined for each Maryland grid cell, an area
10,000 feet by 10,000 feet. The presence of wells in each of
the major aquifers was noted and mapped (see Map Sheet 1).
in Area B only two representative wells in each grid cell
were mapped; however,, all wells listed in the well permit
computer printout were used to determine aquifer use. Map
Sheet 3 shows the general aquifer use patterns in Dorchester
County.

Ground-Water Conditions

Information on the geology, soils, and ground-water
availability in Dorchester County is available from a number
of different sources. Information on soil resources can be
found in the Soil Survey of Dorchester County, Maryland
(Matthews, 1963). Maryland Geological Survey Report of
Investigations #17 (Mack et al, 1971), #18 (Rasmussen and
Slaughter, 1957), and #40 (Bachman, 1984) provide information
on the hydrogeology and water resources of Dorchester County.
A description of the uppermost geologic deposits and
corresponding stratigraphy are found in U.S. Geological
survey Professional Paper 1067-A (Owens and Denny, 1979) and
the Geologic Map of Dorchester County (Owens and Denny,
1986). These resource documents provide a basic
understanding of the distribution of the shallow
hydrogeologic conditions in Dorchester County important to

A -- 4

the management of ground-water resources and on-site sewage
disposal systems.

Dorchester County lies on the Atlantic Coastal Plain, a
wedge-shaped mass of unconsolidated sedimentary deposits
which overlie hard crystalline rocks. The stratigraphy and
associated nomenclature for geologic units of the eastern
shore coastal plain are indicated in Table 6. Geologic units
found in Dorchester County vary somewhat from that shown in
Table 6. The shoreline complex geologic unit refers to the
Kent Island Formation. The upper Miocene complex (Pocomoke
Aquifer, ocean City Aquifer, and Manokin Aquifer) are absent.
The surficial geologic units are the Beaverdam Formation, the
Kent Island Formation, and units of the Chesapeake Group, as
shown in Figure 3.

Within these geologic units are layers of water-bearing
sands and gravels, referred to as aquifers, that readily
supply ground water to wells. Between the aquifers are silty
and clayey layers referred -to as aquitards or confining
units. The principal aquifers found in the study area are:

1) Pleistocene deposits referred to as the Beaverdam
sand or the Columbia Formation. This aquifer also
includes the Pensauken Formation from Owens and Denny
(1986). The Parsonsburg sand may provide water to
drive point wells in a' f ew locations in Area C,
Elliot Island, for example.

2) Sandy and shelly aquifers in the thoptank and Calvert
Formations (Miocene age). In descending order, these
aquifers may be refer-red to in other literature as
the Frederica Aquifer (Choptank Formation),
Federalsburg Aquifer (Calvert Formation), and
Cheswold Aquifer (Calvert Formation).

3) Sands of'the Piney Point Formation (Eocene).

4) The Aquia Formation.

A - 5

TABLE 6
COASTAL PLAIN STRATIGRAPHIC NOMENCLATURE AND
AQUIFERS OF THE EASTERN SHORE OF MARYLAND
(FROM BACHMAN, 1984)

System Series (Group) Geologic Unit Thickness Hydrogeologic Unit(s) Dominant Lithologic Character
(feet)

Holocene Holocene deposits 0- 40 Sall. alluvial sand and silt. dune sand. and peat.
Disconformable base.

Shoreline complex Lenticular deposits of "sand. silt. clay. end past.
Pleistocene Some beds of coarse send and fine gravel. Tan;
game tray and blue clay.
and Pliocene Beaverdam Fm. 0 - 230 Columbia equifer
-
and Beaverdam Sand: Light gray to light tan, fine
(Columbia
Pensauken Fm to coarse grained. moderately sorted. feldapathle
Group) of Owens sand.
and Denny Pennsuken Formation: Light tan to orange tan.
medium to coarse grained. moderately to poorly
(1979) sorted. pebbly feldepathic sand.
0- 50 Upper Lenticular silt*. clays. and flue sands. Green-
confining bed blue silt and flue gray sand most common. but
Upper Miocene occasionally includes blue-green pebbly clay.
Aquifer Complex 0 - 80 Pocanoke aquifer Sand. gray or tan-gray; coarse and pebbly generally.
but locally fine.

Lower Blue and gray clayey silt and sand; some peat.
confining bed Use beds of shell and calcite and/or limestone.
Miocene orktown and Cohanse 0 - 65 Ocean City Coarse gray sand. fine gravel.
Formations (?) aquifer
(Chesapeake of Rasmussen and
Slaughter (1955) Fine to very coarse gray sand. and some lignite or
1 0 - 240 Manokin aquifer past. Same silty sand and clay. Occasional beds
Group) of shell and/or "rock".
St. Marys Formation 0 - 190 Confining layer Cray fossiliferous clay. silt. fine send. and
silty and sandy clay.

Cray fine sand. Thin bed of shell and calcite.
Frederica aquifer
and
Choptank formation 0 - 240 confining Layer Green at brown clay and fine sand. Thin beds of
shell and calcite or limestone.
0 - 680 Cheswold aquifer Gray sand and diatomaceous silt and clay. Shell
and
Calvert Formation confining layers beds.
Piney Point Formation 0 - 220 Piney Point aquifer olive-green to greenish-gray quartz sand. slightly
Eocene to moderately glauconitic; shell beds.
Nanjemoy Formation 0 - 294 Confining layer Gray to dark gray. glauconitic. silt. sand. and
clay.

Aquia and Hornerstown Green to brown, fine to coarse grained. glauconitic
Paleocene Formations (undivided) 0 165 Aquia aquifer sand; Interstratified with grayish-green silt and
lays; calcite cemented sands and fossil beds.
Brightseat formation 0 - <100 Confining layer Dark gray clay and fine. silty. micaceous sand.

Matawan and Monmouth Dark greenish-gray to reddish-brown. fine to
Formations (undivided) 0 - 960 Matawan-Monmouth occasionally coarse quartz sand. Facies say be
Upper aquifer glauconitic. micaceous, shelly and/or clayey.
Cretaceous Light gray to white -sugary". medium to coarse
Magothy formation <50 - 100 Magothy aquifer grained quartz sand and fine gravel; interbedded
dark gray clays in upper pact.

Interbedded. variegated (gray. brown. and red) silt
Aquifers and
Lower Patapsco Formation <50 - 1,750 and clay. and argillaceous, subrounded. fine to
confining layers
Cretaceous medium quartz sand.
White to light gray to orange brown. moderately
(Potomac Group) Arundel and Aquifers and sorted. angular and subrounded quartz sand; also
<50 - 2,950 gray to ocherous silt and clay beds. which occur In
Patuxent Formations confining layers amounts ranging from less than 25% to greater than
(undivided) 75% of formation.
2
go White quartzite conglomerate. dark star. reddish-
green and apple green shales. sandy shales.and
Unnamed 0 - 135
arkosic sandstones. Does not outcrop at the
Eastern Share.

Believed to be chiefly schist. granite. gabbro.
Basement Complex and gneiss.

- The nomenclature Is that of the Maryland Geological Survey-
2/
Compiled from Rasmussen and Slaughter (1957). Hansen (1972 oral commun.. 1982). and Weigle (1974).

A- 6,

76' 75'

20 30 40 AGArs

PENNSTtVANIA

AAARVIAND

C E C-1 L

Cher cow,

V.-

fee

Baltimore

DELAWARE BAY
C4..
%
EXPtANATION!

ESTUAFAW- FLUVWL
39*
35r Annapolis
@wrier beach dePashe jj

IP-1 S S.4pos-a Fw-etian
save Island faria.
-4A
10 kwshire fw@qion

Far."';O.

0
fc-ation

-d
rn S.,

C
Chesapeake Grow

rn Cieclogic comoct. dashed wh-e

,k
0C...
*4 ------- City

76- 75,

Figure 3. Generalized Geology of the Maryland Part of the Delmarva
Peninsula. (From Bachman,, 1984 - Adapted from Owens and
Denny, 1979 and Ownes and Minard, 1979).

A-7

A generalized cross-section showing these aquifer units and
the confining units between them are shown in Figure 4. The
uppermost aquifer throughout the majority of the study area
is the Pleistocene aquifer. A brief description of each of
these aquifers taken from Mack et al (1971) follows:

The Pleistocene Aquifer contains the Beaverdam sands and
Pensauken Formation, often collectively referred to as the
Columbia Formation. Within Area A, the Pleistocene Formation
ranges from a few feet to up to 100 feet in thickness. This
aquifer is known to have a very high permeability and
transmissivity, meaning it can provide large quantities of
water to wells providing that there is sufficient available
drawdown. Wells in the Pleistocene are reported to be
capable of yielding as much as 1,500 gallons-per-minute.
Water quality in the Pleistocene Aquifer is generally good.
Iron levels are relatively low, the water is soft, and low in
total dissolved solids. The Pleistocene Aquifer may have
locally elevated concentrations of nitrates, as will be
discussed in the water-quality section.

The Miocene Aquifers are found in the Choptank and
Calvert Formations. The aquifer in the Choptank Formation is
commonly referred to as the Frederica Aquifer. Within the
Calvert Formation are two aquifers commonly referred to as
the Federalsburg Aquifer and the Cheswold Aquifer. Available
information suggests that the Miocene aquifers may be highly
interconnected and, therefore, behave as a single aquifer,
although in some areas the degree of interconnection may be
limited and each of these aquifers, if present, would behave
as a single aquifer. The water-bearing sands in the Miocene
formations lie approximately 200 to 300 feet below land
surface. Generally, the tratismissivity of these sands is
relatively low, sufficient to support single-family wells,
but have limited yield for larger capacity wells. Water

A 8

ARYLANi) DEPARTMENT OF GEOLOGY- Mom AND WATER REsOURC=
Sw A TEST HOLE
Dor- Dor-
Dor- BfI Bf 24
Dor- Ce3
Cd35

River
z!
SEA LIEVEL 0 _1@@ __T=_KZ EnEll
-77:

30 2
- t�__G.Z
100

ISO - - - - - - -

too

-1:12

too

300

330
7 Z3

400

EXPLANATION
450 PLEISTOCENE AND.- Sand. medium, gravelly;
some silt and clay
Cott-F43 PLIOGENE Q) SERIES
cat -Aw MIOCENE SERIES
st Marys formation clay
Dot mUALOCK Sand. coarse- medium.
Oot-bft4l
shells
r -C.3 sEcReTAFty Choptank formatiots
AMBSUDGE Silt
DORCHESTER CO.
Sand. fine- silty,
A c"uFcm CREEK
shells
Dar-cj 35 to Calvert formation M
_j MILES Silt and clay, diotomaceous
SCALE
EOCENE SERIES tion Sand, coarse-medium
Piney Point forma 01

Figure 4. Generalized Geologic Cross-Section for Northeast Dorchester
County. .(From Rasmussen and Slaughter, 1957)

quality in these aquifers is generally soft. Iron
concentrations are generally higher than those of the
Pleistocene Aquifer. Southeast of Salem in Area C, the total
dissolved solid concentrations are reported to be higher than
the recommended limit of 500 mg/l.

The Piney Point Formation (Eocene age) contains water-
bearing sands from 400 to 500 feet below land surface. It is
the main source of water for Cambridge and is the most
important artesian aquifer in Northeastern Dorchester County.
The transmissivity of the Piney Point aquifer is relatively
high, with one well in the Cambridge area yielding 1,120
gallons-per-minute. However, 'water levels in the Piney Point
aquifer have been lowered extensively in the Cambridge area.
Water quality in the Piney Point aquifer is sufficient for
domestic and industrial purposes withouttreatment in Area A.
In Area C, the dissolved solids content is reported to be
greater than the drinking water standard (500 mg/1) . Water
quality does vary significantly in the Piney Point aquifer
f rom very hard to soft. The very hard waters often contain
excessive iron and are high. South of the Choptank River,
water from the Piney Point Formation typically has an odor of
hydrogen sulfide which requires treatment such as aeration to
remove the gas.

The Aquia Formation Aquif er (Paleocene Age) is present
in the northwestern portion of Area B2, west of Cambridge and
appears to pinch out on a line north of the Choptank River in
Talbot County. It is locally important as a source of
drinking water. The Aquia Aquifer occurs approximately 500-
620 feet below the land surface and varies in thickness
across the study area from 40 to 65 feet. The aquifer is
composed of green quartz sand, moderately glauconitic with a
few lenses of clay and occasional hard (cemented) layers.
The transmissivity of the aquifer is approximately 2000 gpd

A - 10

per foot. Water quality from the Aquia is generally good and
is suitable f or domestic use without treatment. It is soft,
low in iron and contains approximately 300 mg/l dissolved
solids.

Very little is known about the geologic or water-bearing
characteristics of the aquifers below the Aquia Piney Point
Formation throughout the study area. One well penetrating
the Magothy Formation (Cretaceous Age) in the Cambridge area
found the water quality to be relatively soft with acceptable
dissolved solids and iron levels. This aquifer may be
present throughout the area of study, but should not be
considered as a source of drinking water until additional
information is available.

Ground-Water.Use for Drinking Water

Ground water is the sole source for drinking water in
Dorchester County. A general treatment of ground-water
resources of Dorchester County is f ound in the Maryland
Geological Survey Report of Investigations No. 17 (Mack, et
al, 1971) and Bulletin 18 (Rasmussen and Slaughter, 1957).
As reported, the principal aquifers are the Pleistocene
deposits, Miocene aquifers, (i.e., sandy zones in the
Choptank and Calvert Formations), the Piney Point Formation
and the Aquia Formation. The general pattern of use for
drinking water of these four aquifers is shown on Map Sheet
3. Within Areas A & C, the primary sources of drinking water
are the Pleistocene Aquifer and Miocene age aquifers. Use of
the deeper Piney Point Aquifer is principally in Areas Bi and
B21 although wells screened in this unit are found in
scattered locations elsewhere. The Aquia Formation is solely
used in the northwest portion of Dorchester County. The
suitability of deeper aquifers, including the Magothy
Formation as a source of drinking water, has not been fully

A -- 11

determined. At least one well. is known to withdraw from the
Magothy in the Cambridge area. Mack, et al, (1971) indicates
it may be a significant source.

The available information suggests that, should the
surf icial aquifer become contaminated, there appears to be
deeper confined aquifers capable of supplying limited
quantities of drinking water. In Area B the Miocene age
aquifers (Choptank and Calvert Formations) appear to be
discontinuous across the area and may not always be present
as a deeper replacement source to the Pleistocene Aquifer.

The uppermost aquifer is rarely used in Areas B1 and B2.
In most cases, wells are screened in the Piney Point
Formation and, where available, the Aquia Formation. Because
of its limited use, little information is available
concerning water quality of the surficial aquifer in Areas B1
and B2.

Within Area C, the uppermost aquifer may be a thin sandy
zone within the Kent Island Formation or within the thin
Parsonsburg sand deposits, as is the case at Elliot Island.
These units are used as sources of drinking water in
scattered locations. The Miocene age aquifers are also used
and, rarely, the Piney Point aquifer. The available
information indicates that both the Miocene age aquifer and
the Piney Point aquifer may not in many, cases meet secondary
Drinking Water Standards (i.e., total dissolved solids less
than 500 mg/1) in Area C.

Ground-Water Ouality in the Surficial Acruifer

The quality of ground water in the surficial aquifer
within the study area is generally reported to be good and
can be used for most purposes without treatment (Mack, et al,

A -- 12

1971). However, little information is available on the many
constituents of concern to human health. The principal
ground-water-quality concern for drinking water is the
elevated nitrate levels in the Pleistocene Aquifer (Area A).

Bachman (1984) reports that of 604 water samples taken
from wells in the Pleistocene Aquifer across the Delmarva
Peninsula, over half of the samples had nitrate
concentrations of 3 mg/1 as nitrogen or higher, indicating
that the water in the aquifer has been affected by human
activity. He also reported that nitrogen concentrations
exceeded the primary drinking water standard of 10 mg/l in 15
percent of the samples. Nitrate concentrations were found to
be higher in areas of urban and agricultural land uses and
well drained soils.

Bachman (1984) concluded that the major factors
affecting nitrate concentration are the presence of a
nitrogen source, hydrogeologic conditions, and soil drainage.
Areas with poorly drained soils may have a lower nitrate
concentration due to a soil chemical environment t hat
promotes denitrification. Sources of nitrate that enter the
ground water with recharging infiltration include on-site
wastewater disposal, lagoons, agricultural fertilization,
feed lots, and poultry production facilities and lawn
fertilization. The high nitrogen levels in some areas were
thought to occur due to the rapid leaching through sandy
soils. Sandy, well-drained soils have a chemical environment
that promotes the nitrification of the other fo rms of
nitrogen and limits chemical processes that remove nitrates
(i.e., denitrification).

Water-quality standards for ground-water in Type I and
Type II aquifers have been set as part of COMAR 10.50 (see
Table 7) . These standards include heavy metals, selected

A - 13

TABLE 7.
MARYLAND GROUND-WATIER QUALITY STANDARDS
COMAR 10.50

Inorganic Chemicals

Arsenic 0.05 mg/l
Barium 1.0 mg/l
Cadmium 0.010 mg/1
Chromium 0.05mg/1
Lead 0.05 mg/l
Mercury 0.002 mg/l
Nitrate (as N) 10.0 mg/l
selenium 0.01 mg/l
silver 0.05 mg/l
Fluoride 4-.0 mg/l

organic chemicals

Endrin 0.0002 mg/l
Lindane 0.004 mg/l
Methoxychlor 0.1 mg/1
Toxaphene 0.005 mg/l
2,4-D 0.1 mg/l
2,4,5-TP, Silvex 0.01 mg/l
Total trihalomethanes 0.10 mg/l

Radioactivity
combined radium-226 and 5 pCi/l*
Radium-228
Gross alpha particle activity 15 pCi/l
activity (including
radium-226 but excluding
radon and uranium)
Average annual concentration 4 millirem per year
of beta particle and photon
radioactivity not to produce
annual dose equivalent
greater than

pCi/l=picocuries per liter

A-1 L

inorganic parameters (including total dissolved solids) and a
f ew volatile organic chemicals and pesticides. With respect
to on-site wastewater disposal systems,, the principal
constituents of concern are nutrients, (e.g.,, nitrates and
phosphates) and pathogens (i.e., bacteria and viruses).

Nitrates are commonly used as an indicator of the
presence of other constituents of concern to public health.
For example, in agricultural areas, nitrate-contaminated
ground waters may also be found to carry leachable
pesticides. For this reason, G&M chose to focus on nitrate
levels in -the surficial ground waters and shallow ground
waters. The water-quality data included approximately 87
wells where nitrate concentrations were available and the
lithology or the zone of well withdrawal could be clearly
determined. The location of these wells and the nitrate
content, mg/l, is displayed on Map Sheet 4. These samples
were primarily taken front the Pleistocene Aquifer.
Approximately 12 percent of the well samples had a nitrate
content greater than the drinking water standard of 10 mg/l.
The mean nitrate concentrations in surficial ground waters in
the area of study was 5.7 mg/l. These results are similar to
those reported by Bachman (1984).

Two distinct areas were delineated where the nitrate
concentrations appear to be elevated, (i.e., concentrations
greater than 5 mg/1) as shown on Map Sheet 4. One such area
is in the vicinity of Hurlock and Solomon's Temple. A second
area of elevated nitrate concentrations occurs to the north
and east of Eldorado. Because of the limited use of the
surficial aquifer in Areas BI. and B2, nitrate data is not
generally available. A listing of nitrate values are
provided in Appendix B.

A - 15

Presence of Confining - units within 25 Feet of Land

Surface

A major emphasis of the investigation was to determine
the presence of continuous confining units within 25 feet of
land surface that are five :feet or greater in thickness.
Examination of lithologic logs, including well completion
logs, indicates that such units, if present, are relatively
sparse in Area A. Data obtained from well completion logs
and back hoe pit descriptions have been compiled and are
maintained by the Dorchester County Department of Health.
This data indicates that there is a laterally extensive
confining unit present in Area B. The data were insufficient
to draw conclusions about Area C. For this reason, it is
recommended that specific site investigations be performed
where the presence of such a confining unit is suspected.

Information available from the U.S.D.A. Soil Conserva-
tion service indicates that large portions of Areas A and C
are underlain at shallow depth, i.e. within 5 to 10 feet, by
a thin, 6- to 24-inch, silty layer of varying thickness. A
typical soil description with such a layer is provided in
Table 8. The thin silty layer is present generally below the
elevation of 35 feet in Area A. The occurrence of this thin
silty layer is generally recognized but its presence at any
site should be field verified.

The thin silty layer may, provide additional protection
to underlying ground waters due to 1) a chemical environment
favoring denitrification, 2) fine pore sizes to enhance
filtering, and 3) an order-of --magnitude smaller permeability
than overlying sands that promotes lateral flow toward

surface waters.

A - IL 6

MUILE 8.
SOIL PROME IZSCRIMCN OF IN=SI]DE SOIL SERIES
WITH SILTY RESTRIMVE UNIT AT 56 TO 72 INCHES
(WJRrESY OF USDA SOM OONSMWMCN SERVICE)

Typical Pedcn: Ingleside sandy loan, on a smooth one percent slope in a
cultivated field. (colors are for moist soil).
Ap-0 to 10 niches; dark brown (10YR 4/3) sandy loam; moderate fine
granular structure; very friable, slightly sticky, slightly plastic,
ccMMOn very fine, and few fire, and medium roots; common very fine tubular
pores; slightly acid; abn:pt smooth b=x1ary. (7 to 3-1 inches thick)

E-10 to 15 inches; brown (10YR 5/3) sandy loam; weak medium
cq mngular blocky structure; very friable, slightly sticky, slightly
plastic; ccumon fine and very fine roots; many very fine, and common fine,
and few medium tubular pores; slightly acid; abrupt smooth boundary. (0
to 5 inches thick)

Btl-15 to 24 inches; dark yellowish brown (10'YR 4/6) sandy loam;
moderate medium subangular blocky structure; friable, slightly sticky,
slightly plastic; common very fine and fine roots; ccmm=i very fine and
fine tubular pores; common distiry-t clay film on faces of peds and clay
bridging between sand grains; slightly acid; very clear wavy boundary. (4
to 15 inches thick)

Bt2-24 to 33 inches; strong brown (7.5YR 4/6) sandy loan; moderate
medium. subangular blocky structure; friable, slightly sticky, slightly
plastic; few very fine roots; common very fine and fine tubular pores;
cammon prcminent clay films on faces of peds and clay bridging between
sand grains; slightly acid; clear wavy boundary. (6 to 15 inches thick)

BC-33 to 43 inches; yelladixdli brown (101M 5/6) sandy loam; wea&
medium subarqular blocky structure; very friable, slightly sticky,
slightly plastic; few very fine roots; common very fine and fine irregular
pores; clay bridging between sand grains; slightly acid: gradual wavy
boundary. (2 to 10 inches thick)

Cl-43 to 48 inches; yellowish brown (10YR 5/8) loamy sand; single
grain; loose; few very fine and fine irregular pores; moderately acid;
clear wavy boundary. (9 to 25 inches thick)

C2-48 to 56 inches; light yellowish brown (10YR 6/4) loamy fine
sand; common medium distinct light brownish gray (10YR 6/2) mottles, and
common medium prominent strong brown (7.5YR 5/8) mottles; single grain;
loose, moderately acid; clear smooth boundary. (6 to 10 inches thick)

2C3-56 to 72 inches; pale brown (10YR 6/3) silt loam; common medium
faint gray (10YR 6/1) rattles, and common fine prominent strong brown
(7.5YR 5/8) mottles; massive; friable, slightly sticky, slightly plastic;
moderately acid.

A- 1 7

I
I
I APPENDIX B

INVENTORY OF NITRATE LEVELS IN
I GROUND-WATER SAMPLES FROM DRINKING-WATER WELLS
I
I
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I
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I
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I
I

APPENDIX B

INVENTORY OF NITRATE LEVELS IN
GROUND-WATER SAMPLES FROM DRINKING-WATER WELLS

Screened Sample
Map-Parcel No. Interval Date Nitrate
(feet) (mcfzl)

43-60 37-42 7/75 10.6
43-146 79-89 3/1/78 0.38
43-180 <30 4/15/74 0.14
45-71 50-55 Unknown 3.0
45-82 70-80 11/19/79 8.4
45-121 <30 Unknown 0.15
46-17 47-51 Unknown 3.5
32-9 <30 11/25/80 7.1
33-49 <30 2/28/74 4.0
33-50 <30 10/9/74 .2.4
33-64 92-102 5/5/86 3.8
33-86 70-80 2/3/75 6.2
34-54 50-60 6/28/76 0.36
34-54 <30 12/20/84 <0.2
34-56 85-95 12/18/78 <0.2
34-71 34-38 8/25/82 0.7
34-81 <30 Unknown 0.14
34-98 <30 8/24/77 0.32
34-108 <30 3/10/86 <0.2
35-3 <30 Unknown 11.1
35-6 26-61 11/13/86 11.5
35-25 29-34 10/28/85 3.4
35-40 35-40 12/13/84 <0.2
35-41 28-33 10/23/78 0.1
35-59 32-37 10/1/74 8.0
35-72 55-65 8/12/84 9.6
35-85 90-100 9/6/78 0.32
36-2 93-103 7/15/87 3.9
36-19 65-70 2/19/87 3.9
36-31 65-72 3/19/81 4.7
36-39 45-50 4/21/80 3.3
36-64 34-39 8/11/76 1.0
36-68 45-50 1/27/83 7.6
36-84 38-43 1/17/85 6.4
36-121 58-63 12/2/82 8.8
36-144 25-30 8/9/76 6.32
36-152 55-60 4/14/86 8.8
36-156 45-50 9/18/80 4.0
36-161 59-64 2/3/83 4.9
36-1 50-58 2/27/73 0.0
36-76 75-85 6/6/85 7.4
36-160 <30 5/17/78 14.4
36-161 65-75 Unknown 3.6

El 1

APPENDIX B

INVENTORY OF NITRATE LEVELS IN
GROUND-WATER SAMPLES FROM DRINKING-WATER WELLS
(Continued)

Screened Sample
Map-Parcel No. Interval DAe Nitrate
(feet) (mg/1)

22-32 33-37 8/2/84 14.4
22-60 74-94 Unknown 3.38
22-137 <30 10/8/74 4.0
22-172 51-58 3/22/84 1.1
22-191 85-95 Unknown 4.4
23-3 39-94 3/12/79 11.6
23-10 84-94 11/8/79 5.2
23-18 50-54 2/19/81 5.7
23-87 46-48 Unknown 2.2
23-91 47-54 2/28/79 1.4
23-106 85-95 3/12/81 2.2
24-3 79-84 6/6/77 0.17
24-4 32-36 6/30/83 8.2
24-8 <30 9/21/81 4.9
24-12 82-90 12/10/81 4.8
24-17 <30 9/13/78 0.2
24-24 43-47 8/13/85 12.2
24-28 50-60 1/8/80 <0.2
24-79 <30 11/l/84 10.0
24-80 38-48 8/2/84 0.4
24-85 38-43 7/22/74 4.0
25-5 39-49 Unknown 7.5
25-42 70-80 1/16/80 0.6
25-60 70-80 Unknown 0.7
13-46 80-90 8/10/76 0.1
13-60 <30 5/19/75 28.8
13-63 54-94 6/17/76 5.6
13-64 <30 6/17/80 9.5
13-68 80-90 10/29/80 8.6
13-70 54-94 10/29/80 8.6
13-71 40-80 4/28/75 13.8
13-130 48-50 3/19/79 14.8
13-130 40-46 12/5/78 9.1
14-171 47-57 4/28/81 4.9
14-252 30-34 9/25/78 8.0
15-19 60-90 2/28/79 3.5
15-57 65-70 6/11/75 2.2
16-23 51-61 7/19/77 1.8
16-26 50-60 11/15/84 5.9
16-26 50-60 1/3/85 2.4
16-48 <30 2/4/75 56.3
16-49 <50 2/2/65 8.0
16-52 <50 9/30/74 4.0
16-57 47-51 12/2/82 2.3

11 2

I
I
I APPENDIX C
I NITROGEN LOADING CALCULATIONS
I
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I

APPENDIX C

NITROGEN LOADING CALCULATIONS

Method #1: Cornell Nitrogeri-Balance

W = (4.43) (C) + a(P-ET) - cP
(y - a) - y (d + n)

Where:
W = wastewater loading (acre/acre - year)
C = removal of nitrogen aS crop (lb/acre-year)= 0
a = allowable N concentration in percolat (mg/l= 10
P = precipitation (acre-inch/acre-year infiltration= 15
ET= potential Evapotranspiration (ac-in/ac-yr)= 0
c = concentration of N in precipitation (mg/l)= .5
y = concentration of N in wastewater (mg/l)= 60
d - fraction of N denitrified (% x 10-2)= 0 -2
n = fraction of N volatilitized as ammonia (% x 10' )= 0

W = (4.43) (0) + 10 (15 -- 0) - (.5).(15)
(60 - 10) - 60 (0)

= 0 + 150 - 7.5 = 142.5. = 2.85
50 - 0 50 acre - Inch/ac - yr.

Home WW generation 450 gpd = 164,250 gals/year
27,150 gallons/acre - inch = 6.05 acre - inch/ac - yr
2.85 acre - inch/ acceptable loading

2.12 acres/home required to maintain acceptable N
loadings to groundwater.

NITROGEN LOADING CALCULATIONS

Method #2: Douglas - Trela Nutrient Dilution Model

DWQ 1 (CL)
640 (R) (CE) (QE) P

where:

DWQ = development density based on H20 quality for
septic systems (DU/acre)
(mgd/mi2 infiltration to ground water recharge

C - 1

APP [DIX C

CL = pollutant concentration limit (mg/1) = 10
640 = conversion factor (acres/m12)

R = pollutant renovation factor (decimal
fraction) = .9 (Case 1) and .7 (Case 2')

CE pollutant concentration in septic effluent
(mg/1) = 60

QE = septic effluent, generation (gpcd) 450 gpd

P = unit occupation (persons/DU)

15 "/yr. x 27,150 g/acre - inch 407,250
gallons/acre yr. = .407250 mgy/ac. x 640 ac/mi2 365
.7141 mgd/Z

(.7141 x 106) 7141
60 (.9) (60) (450) 15.552

Case #1 (loamy sand)'
.5 Du/Acre 2 acres/DU

(2.18 ac/DU)

Case #2 (sandy loam)
(.7141 x 106) (10) (7.141)
640 (.7) (60) (450) 12.096
.6 DU/Acre 1.7 Ac/DU

C 2

1.
I
I APPENDIX D

HYDROGTEOLOGIC
I GUIDELINES
I
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I

APPENDIX D

HYDR03EOLOGIC
GUIDELINES

Introduction

A. Purpose of Study
B. Project Proposal

1. Project Description
2. Proposed Water Supply
3. Proposed Wastewater Disposal
4. Estimated Wastewater Design Flows

Site Description

A. Location
B. Topography and Surface Drainage
C. soils
D. Geology
E. Groundwater

1. Aquifers
2. Well Inventory

Subsurface InvestigLtion

A. soil Map

1. Detailed Map and Legend
2. Soil Profile Descriptions

a. Test Pits
b. Auger Holes

B. Geologic Framework

1. Areal Extent and Thickness of Substratum
Sands.

2. Hydraulic Conductivity Measurements -
estimated wastewater flows > 10,000 gpd
require pumping tests with (3bservation
wells; number and duration of tests to be
proposed by consultant based on
hydrogeologic framework.

D -- 1

APPE19DIX D

3. Areal Extent, Thickness, Nature, and
Continuity, of confining layer (s)
available to protect existing/potential
water supply aquifers from impact of
proposed sewage disposal where maximum
sewage treatment will be provided (e.g.,
direct penetration of groundwater.

4. Underlying, Aquifer - physical and water
quality description where maximum sewage
treatment will not be provided (e.g.,
direct penetration of groundwater).

C. Groundwater Conditions

1. Potentiometric Surface Map
2. Water Quality Data

IV. Analysis

A. Conceptual Design
B. Impacts

1. Treatment and Ground-Water. Movement away
from site

2. Surface Water Impacts if applicable based
on proximity, environmental sensitivity

V. Conclusions

Vi. Recommendations

VIII. Appendices

A. Well Survey Data
B. Well Logs
C. Soil Descriptions/Test Pits
D. Boring Logs and laboratory Analyses
E. Monitoring Well Construction Details
F. Mounding Analyses
G. Water Quality Analyses
H. Large Scale Maps/Geologic Cross Sections

D -- 2

APPENDIX E

STATUS REPORT
TO THE
GOVERNOR AND GENERAL ASSEMBLY
ON THE

STATE OF MARYLAND
INNOVATIVE AND ALTERNATIVE
ON-SITE SEWAGE DISPOSAL PR0GRAM

FEBRUARY 1987

DEPARTMENT OF HEALTH AND MENTAL HYGIENE
OFFICE OF ENVIRONMENTAL PROGRAMS
WATER MANAGEMENT ADMINISTRATION
INSPECTION AND COMPLIANCE PROGRAM
DIVISION OF RESIDENTIAL SANITATION

TABLE OF CONTENTS

PACE

ACKNOWLEDGMENTS .................................. I
EXECUTIVE SUMMARY ....... I
I NTRODUCT I ON ...................................... 9

BACKGROUND ... 9
PROGRAM DESCRIPTION ............................. 10
Purpose and Scope
Objectives
Evaluation Criteria
Activities
PRELIMINARY FINDINGS ......... .............. 17
TECHNICAL ISSUES ............................... 17

Site Limitations
Adequate Treatment
Construction Practices
Equipment Problems
Operation and Maintenance
Management of On-Site Systems
SYSTEMS UNDER EVALUATION ...................... 20
Soil Treatment Systems
Groundwater Penetration Systems
Solar Systems
STAFF REQUIREMENTS ............................. 25
PROBLEM INVESTIGATIONS .......................... 27
CONCLUSIONS ....................................... 28
RECOMMENDATIONS ................................... 29
REFERENCES ........................................ 31
APPENDICES

APPENDIX A

APPENDIX B

ACKNOYLEDCAIENTS

We acknowledge and appreciate the assistance of each of the
local county health departments and property owners throughout
the State that have cooperated and contributed to the progrcm.
In parficulor, we wish to thank Wayne Asplen, formerly of the
Dorchester County Health Department, Rich Piluk of the Anne
Arundel County Health Department, and Walter Raum, formerly of
the St. Mary's County Health Department, for their pioneering
efforts and voluabli contributions.

This report was prepared under the direction of
Jack R. Holthous, R.S., Ch?ef of the Division of Residential
Sanitation, by Clifford E. Stein, Soil Scientist, with
contributions from Ch.ing-Tzone Tien, Pjublic Health Engineer,
Jane C. Gottfredson, Geologist, Tom TeUtsch, Jay Prager, and
Barry Glotfelty, Sanitorions. Other Division staff who have
contributed to this effort are: John Cov'01t, Dave Kerr and
Norman Lowery, Regional Consultants; and Clyde Boatwright,
Environmental Health Aide. A special thanks is extended to
Theresa German for typing and word processing.

EXECUTIVE SUMMARY

ACCOMPLISHMENTS TO DATE

Since 1980, the program has accomplished the following:
1. Eight basic on-site experimental systems have been
identifiEd for evaluation:

Soil Treatment_Systems

sand mound
- shallow pressure dosing trench
- sand-lined pressure dosing trench.
- alternating fields

Groundwater Penetration Systems

- sand-lined trench
- sand filter trench
- bermed infiltration pond

Solar Systems

2. Two-hundred and seventy three (273) detailed site
evaluations have been conducted.

3. Seventy-nine (79) experimental systems have been or are
being installed. Seventy-two (72) for single family
resi dences and seven for larger, multi-use systems ranging
from 1,200 to 16,000 gpd.
4. State I/A grants of $37,500 have been provided to eight
counties including Anne Arundel, Kent, St. Mary's,
Washington, Allegany, Cecil, Charles and Wicomico
Counties. Harford; Carroll, Dorchester and Garrett' are
likely,to become grant participants by July 1987.

5. Training is being continuously provided to local health
departnien ts and con trac to rs .122 sanitarians have
participated in site evaluation training workshops which
continue to be held throughout the State on a regional
basis. Design and construction workshops are presently
scheduled for January, February, March and May in four
locations around 'the.State.

6. Currently, I/A staff of OEP directly monitor 20 experimental
systems throughout the State. By the end of calendar year
1987, this total is expected to increase to 50.

7. COMAR 10.17.02 was adopted in April 1986 incorporating
provisicns which provide for approval of I/A projects with
specific approval of sand mounds to accommodate high water
table situations. New grant regulations C014AR 10.17.16 were
also adopted which specify how State I/A grants are to be
made to local governments and how I-ocal governments in turn
distribute funds to homeowners.

SYSTEMS UNDER EVALUATION

The eight basic experimental systems under evaluation are all
designed to address specific site limitations which relate
either to hydraulic performance or soil treatment of
wastewater. Site limitations most often encountered include
slow to impermeable soils and high wa.-ter table or shallow soils
over fractured bedrock. In the first instance, water will not
percolate and ponding and runoff probleps are encountered,
whereas in the second instance' sewage may contaminate
groundwater. Following is a description of each of the eight
basic experimental systems and the site limitations which the
technology is designed to overcome.

Soil Treatment Systems

Systems in this category incorporate.a two to four foot
treatment zone which provides for re-novation of effluent
before it is discharged to groundwater or fractured bedrock.

Sand Mound. This system consists of a double-compartment
septic tank, pump,-pumping C*hamber and an absorption bed
elevated above the natural soil surface in a suitable sand
fill. Septic tank effluent is pumped into the bed through a
pressure distribution network. Treatment occurs as effluent
,moves downward through the sand fill and into the underlying
soil. This system has been studied intensively by a number-
of investigators and states throughout the country. The
Wisconsin site criteria and design are the most accepted and
are currently used in this program with two modifications.
A cylinder infiltrometer -test, that estimates vertical
permeability, is 6sed instead of a percolation test and the
sand fill specifications are more restrictive. It has been
reported that these systems can overcome the following site
limitations:

a. Permeable Soils with High Water Tables;

b. Shallow Permeable Soils Over Fractured Bedrock;

C. Slowly Permeable Soils.

Nineteen systems are currently under evaluation in the
program. Sixteen systems are on permeable soils with high
water tables and three are on slowly permeable soils. The
systems on permeable so'ils with high water tables have

Page 2

performed well and generally confirm available data. In
1986, the first step in converting sand mound systems to
conventional use was taken., Sand mounds for permeable
soils, with percolation rates less thin 30 minutes/inch and
high water tables two feet. or deeper, were included i n COMAR
10.17.02 as conventional systems. Two systems on the s I owl y
permeable soils are under-utilized and the 'third is
currently experiencing mechanical problems. Results for
slowly permeable soil are therefore not conclusive at this
time. Additional mound systems on slowly permeable soils
are needed to help answer questions regarding soil damage
and compaction during construction and the possible use of
up-slope interceptor drainage on sloping sites to divert.
perched water.
2. Shallow Pressure Dosing Trench. This system consists of a
double-compartment septic tank, pump, pumping chamber and
soil absorption trenches. The trenches generally range
between 0.5 and 2.0 feet in width., 1.0 and 1.5 feet. in depth
and are excavated with a ditch-witch. This system, has been
and studied primarily by North Carolina and several other
states. This system allows; shallow placement in the soil t o
maintain two feet or greater treatment Zones below the
bottom of trenches. PresSUre dosing-, provides uniform
distribution of effluent throughout. the trenches and dosing
and resting cycles. It has been reported that these system
c a novercome the following site limitations:

a. Permeable Soils with High Water Tables

b. Shallow Permeable Soils; Over Fractured Bedrock

C. Slowly Permeable Soils

Over forty-four of these systems have been installed or are
under construction. Six systems are currently under
evaluation in the program. Thirty-eight systems were
-installed in the Harney Project in Carroll County and were
evaluated by consultants. Four out of the six systems being
evaluated by the State, experienced construction related
problems with one chronic failure occurring. Additional
study of systems installed in Harney and other locations
throughout the State is planned. Treatment capability,
groundwater mounding and freezing problems that have been
reported by other States will be evaluated. On sloping
sites, up-slope interceptor drainage to divert pershed water
tables will also be studied.

3. Sand Lined Pressure Dosing Trench. This system consists of
a double compartment septic tank, pump, pumping chamber and
soil absorption system constructed in sand fill. Two-foot
treatment zones are being used. These systems can only be
used where underlying soils are sandy and will not be

damaged by construction. This system is similar 4#6-o sand
lined systems that are installed in Delaware and
Pennsylvania. This system is designed to overcome the
following site limitations:

a. Very Slowly to Nearly Impermeab-le Soils

b. Permeable Soils Over Fractured Bedrock

C. Slowly Permeable Soils

No systems are installed at this time. Plans are underway
to hav-e systems constructed in 1987. Evaluation of
treatment capability and construction methods'will be
undertaken.

4. Alternating Fields. This system consists of a double-
'lve and two soil
compartment septic tank, diversion va
absorption fields. -Wastewater is diverted to each field
alternately, allowing one to rest and be rejuvenated by
.j
biodegradation of the clogging mat. It has been reported
that this systen, will extend the design life of the soil
absorption field and would allow each field to be designed
with 25% less effective soil absorption area. Very little
data are available to support this claini. These systems are
being evaluated to overcome site limitations of slowly
permeable soils.

One system is being evaluated and plans for additional
systems to be installed are 'underway.

Groundwater Penetration Systems

These systems are constructed to discharge directly to
surficial groundwater'. They are similar to conventional
groundwater penetration systems with the exception that they
are designed to provide better treatment of effluent before it
is discharged. Areas in the Coastal Plai.n where these types of
systems may be utilized are to be further evaluated through the
process of preparing "Groundwater Protection Reports" (GPR's)
recently required in COMAR 10.17.02.

5. Sand-Lined Trench. This system consists of a double
compartment septic tank and soil absorption trenches. The
trenches are constructed to discharge directly to
groundwater but are backfilled with sand -fill instead of
gravel . The trenches may be elevated above the original
land surface in an impermeable fill in order to obt-ain
adequate hydraulic head for performance when the water table
is high. This system has been used in Maryland to overcome
site limitations of permeable to nearby impermeable soils
with high water tables.

Page 4

Hundreds of these systems have been installed in the past on
the eastern shore coastal plain. The majority are in parts
of Worcester, Dorchester, Somerset, and Talbot county. Two
systems are being evaluated in this program with plans to
include more. Treatment capability and design criteria are
being studied.

6. Sand Filter Trench. These systems consist of a double-
compartment septic tank, pump, pumping chamber, sand filter
and soil absorption trenches. Designs include buried, free-
access and recirculating sand filters that incorporate a
variety of modifications to reduce nitrogen, phosphorus and
fecal coliforms. These systems are designed to overcome
limitations of high ground water.

Seven systems are under evaluation with plans to install
more.

7. Bermed Infiltration Pond. A bermed infiltration pond is an
excavation approximately eight to ten feet deep with no less
than 10,000 square feet in surface area. The excavation
exposes a water-bearing substratum overlain by an
impermeable soil. Part of the excevated material is placed
around the pond perimeter to form a berm. The water from
the substratum rises and falls in the pond in accordance
with seasonal fluctuations in the water table. Septic tank
effluent is discharged near the bottom of the pond for
disposal. The biological organisms in the pond complete the
treatment process and the water moves into the surficial
groundwater surrounding the pond or evaporates.

Over fifty of these systems have been installed in the
Eastern Shore Coastal plain, primarily in Dorchester
County. They are reported to perform well and are proposed
to be converted into conventional use by the end of 1987. A
few questions regarding design and construction remain to be
answered.

Solar Systems.

These systems are for the most part independent of soil
conditions and therefore theoretically would overcome all site
limitations. They consist of a double-compartment septic tank
or aerobic tank with discharge within a greenhouse unit. Two
basic types have been identified, but only one type is being
evaluated. Four systems have been installed. Data collected
in 1985 indicated major problems with these systems. In
addition, the systems appear economically prohibitive. A
contract with the University of Maryland was entered into in
August 1986 to perform a more thorough technical evaluation.
The final report is due in July 1987 and will provide
information for future direction.

Page 5

SCFEDU_E FCR DECISICM

Each of the eight technologies are being installed in different
soil-hydrogeologic settings across the State. Some have more
potential than others and will offer greater opportunity for
success. Sand mounds offer the most opportunity and solar
systems the least. The attached chart entitled "Proposed
Decision Schedule" reflects the Department's best judgment as
to when decisions are likely to be made with regard to approval
of each of these new technologies. Systems for which decisions
will be made earlier than others reflects a greater data base
usually associated with a greater number of installations,
intensive monitoring and higher success rates.

It should be noted that OEP's next technology approval is
slated for July 1987 and consists of extending percolation
rates to 60 minutes for sand mounds. We also anticipate
approving bermed inf i I trotion ponds a"s -conventional technology
and making a final decision on the use of the solar system. By
Decernbe@r 1987, OEP expects to have enoubh operating data an
sand-lined trenches employing groundwater penetration to have
completed design criter*io which could be uniformily applied to
all Coastal Plain Counties. This criteria will be subsequently
included in Regulation 10.17.02 which should be finalized
within an additional four to six months.

CONCLUSICNS

1. Training and Staffiaq

Training local sanitarians to make site evaluations, review
designs, make const'ruction inspections and to advise
homeowners on O&M requirements for each new technology
translates into increased workloods.

2. Data Collection Process

Widely-varying hydrogeologic conditions throughout Maryland
require that new technologies be tried in a variety of
different settings before general criteria can be
established. Systems studied the most to date address high
groundwater problems. Slowly permeable to impermeable soils
present the greatest problem and fewer technologies have
been evaluated to address these site limitations. Costs of
large systems designed using lower permeability rates
preclude many from installing them for experimental
purposes. For these reasons, it is anticipated that
sufficient rn-onitori,ng data to make policy decisions may not
be available for several technologies until 1991 or 1992.

3. Construction Problems

Maryland's experience to date, along with that of many other
states, is that construction practices are critical to the
successful cperation of new technologies. In order to

Page 6

address this issue, UP is developing workshops for
installers and is developing capabilities within county
health departments to inspec t projects during construc tion.

4. Approvals of New Technolo ies in 1987

Existing evidence supports:

a . increasi ng perc rates to 60 minu tes for sand mounds and

b. allowing the use of bermed infiltration ponds.

Prel in. inary indications are tha t solar systems are not cost-
effective.

Pol icy statements on each are to be developed by July, 1987
with final rule making by December 1987.

5 . Operation and Maintenance

Each new technology is more-complex than existing
conventional systems and requires increased homeowner
responsibility and unders ta n d i n g .Educational proqrams and
materials need to be developed to provide the homeowner with
an understanding of these systems.

6. Costs

I/A technologies may.cost two to three tines as much as
conventional technologies. Although developers are anxious
to try anything which -dill allow for approval of new
projects, existing lot owners find these technologies
difficult to afford. As a result, not as many existing to-
owners are offering to try an I/A technology on an
experimental basis as was anticipated.

7. Regional Differences

Many of these I/A technologies may overcome site I imitations
in some hydrogeologic areas but not in others. Technologies
employing the use of soil treatment zones may prove useful
throughout the State, whereas groundwater penetration will
have limited application within areas of the Coastal Plain.

2/03/87

INTRODUCTION

This status report has been prepared for the Governor and
General Assembly in accordance with Sect.ion 2, Chapter 498, Acts
of 1986 (HB 828). The report describes the Department of Health
and Mental Hygiene's (DHMH) Innovative and Alternative On-Site
Sewage Disposal Program and presents preliminary findings,
conclusions, recommendations and a proposed decision schedule.
Information on sand-lined trench systems is included in this
report.

BACKGROUND

Reorganization of environmental programs within DHMH in July 1980
provided new opportunities to enhance the-*.study and use of
innovative and alternative on-site sewage disposal systems in
Maryland. An Innovative*and Alternative (I/A) section, within
the Division of Residential Sanitation, was created using
existing staff to identify and evaluate on-site technologies and
coordinate with local county health departments. Division staff
assigned to the I/A section consisted of three professionals that
devoted approximately hal f-time to evaluation of on-si te
technology. Increased staffing at the local county-health
department level was not funded.

In 1983, the EPA Chesapeake Bay Study recommended that the State
c.ontinue to evaluate the applicat-ion of innovative and
alternative technology to problems of wastewater disposal (1)
As a result, one of the 1984 Chesapeake Bay Program Point Source
Pollution Control Initiatives was to enhance the existing on-site
I/A program with additional staff and funding (21. One full-time
professional position was filled during FY85 and'three full-time
positions were filled during FY 86.

In addition to the Bay I/A initiative, authority and funding for
development of an on-site I/A grant program was established by
the legislature in 1984 (3). This program was to provide grants
to assist eligible applicants with construction costs of
experimental systems. DHMH was authorized to develop
regulations, manage the grant program and award grants to
eligible political subdivisions. Political subdivisions would
then in turn award grants to eligible applicants. Grant awards
of $37,500 were made to Anne Arundel , Kent, St. Mary's and
Washington Counties in FY85 and to Alleginy, Cecil, Charles and
Wicomico Counties in FY86. These funds were for construction
costs only and do not include funding for staff work and grant
program admi-nistration at the local county health deparf-ment
level .

Page 8

PROGRAM DESCRIPTION

Purpose and Scope
The purpose of the program is to identi fy and evaluate additional
ty pes of on-site sewage disposal systems that can be used to
remodel failing systems and overcome major site I imitations.
General el i gi bi 1 i ty requi rements for property owner pe rti c ipati on,
in the experimental program are as follows:

1. Public sewer is not available to the property.

2. Property is legally established and is:
a . Improved -with an existing structure but has a f a i l i n g
on-site sewaage disposal system that cannot' be repaired
using conventional methods; or
b Improved with an existing structure but lacks in d oo r
plumbing and cannot meet cUrrent requirements for
installing a conventional on-site sewage disposal
system; or

c Unimproved, was platted before 1972, and cannot meet
curren t requ i rements' for i ns tal 1 i ng a conventional on -
s i te sewa ge di spo sa l sys tem,

3. Property site limitations and conditions are such that an
innovative and alternative system could be designed and
wou l d prov i de us e ful da ta to the S ta tewi de ex pe r imen ta l
effort.

4. Pro pet- ty owne r a grees to cond i t i on s o f t he ex pe r iment and
en te rs i n to a legally b i nd i ng doc ument tha t i s reco rded with
the Deed to the.property.

5. Prope rty i s no t cu rrently proposed to be su bd i v i ded i nto
building lots in-accordance with COMAR 10.17.03.

6. Loca I county hea 1 th de partment has ava ila bl e sta f f to
perf orm de s i gn rev i ewis , cons truc t i on i nspec t i on s and rou t i ne
monitoring.

Final acceptance of eligible properties into the experimental
program and the total number in any one county will be primarily
dependent on meeting mi nim um si te screening cri criteria and
availabil i ty of local staf f for monitoring assi stance. Priori ty
for acceptance is given to improved properties with failing
systems and exist, ing pollution or publ ic health probl ems.
Exceptions to si te cri teria and monitoring requirements for
improved properties wi th pol lution or publ ic heal th problems can
be given on a case-by-case basis.

Experimental systems may be totally financed by the property
owner or, in certain counties, may be partially funded by a State
I/A grant or an indoor plumbing program loan. Eligibility
requirements for obtaining innovative an'd alternative grants and
details of the grant program are outlined in COMAR 10.17.16 and
attachments given in Appendix A.

Experimentation with large innovative and alternative on-site
systems is also within the scope of this program. State I/A
grant funds, however, are not available for these projects.

Objectives .:..

The specific objectives of the program include:

1. Identifying, installing, monitoring and reportin-g on
experimental systems'and the use of these data with field-
experience to develop new State guidelines, design criteria
and regulations.

2. Encouraging local health departments to use identified
technologies in remodeling systems-and for experimental
purposes in order to solve existing pollution-problems and
to enhance the eventual use of I/A technology for new
construction when feasible.

3. Assisting in training local health department staff in
obtaining the expertise necessary to review and approve
designs and inspect system construction.

4. Reviewing applications for construction permits in
cooperation with local health departments until local
expertise can be developed; and evaluating opportunities to
use centralized sewerage facilities as part of the EPA/State
facility planning program.

Evaluation Criteria

Innovative and alternative experimental systems, like
conventional on-site systems, must satisfy basic public health
and environmental protection criteria in addition to meeting
practical considerations. The following sections describe the
criteria that are used to ide.ntif-, and evaluate experimental
systems in Maryland.

Site Limitations. Experimental systems must have potential for
overcoming major site limitations that contribute to on-site
system failures or that preclude the use of land for conventional
on-site systems.

Page 10

Performance.- Experimental systems should meet or exceed existing
performance requirements of conventional on-site systems. The
two mos t important performance requirements are that Systems:

1. Hydraulically Function

System accepts wastewater flows generated throughout the
design life without discharging partially treated effluent
to the land surface or backing up into buildings and
discharging from the plumbing; and

2. Provide Adequate Treatment

A sufficient depth of suitable, unsaturated soil Material is
available below the bottom of the disposal system to provide
a hi gh degree o f treatment before wastewater reaches the
underlying groundwater.

R e I i a b, i I i t yExperimental systems must perform reliably
throughout the design life of the system. C omponents should meet
current industry standards i f available . Designs should maximize
the use of readily available components that have documented
performance records and should incorporate the most appropriate
but simplest control systems whenever possible.

Operation and Maintenance. Since in almost all cases
experimental systems are more complex than conventional systems,
design features should be incorporated to reduce operation and
maintenance requirements whenever possible.

cost. Since in almost all cases experimental systems are more
costly than conventional systems, design features and use of
suitable but inexpensive building materials should be
incorporated whenever po-ssible to reduce cost. In add ition,
minimization of utility energy requirements and maximization or
passive solar energy use should be investigated whenever
possible.

Activities
Activi ties of the program involve ten major types of work
t a s k s .The following sections describe these tasks and summarize
accompl ishments that have been made to date.

System Identification. Published research data, available data
from other States and new proposals are reviewed by OEP staff to
identify conceptually feasible systems for experimentation.
Preliminary site selection criteria, design criteria,
construction guidelines, and monitoring requirements are
developed and reviewed with assistance from county health
department staff. Currently eight basic types of experimental
systems have been identified for evaluation in Maryland. This
@ctivity is ongoing and as new experimental systems are
identified they will be incorporated into the program for
evaluation.

Site Evaluation and Select-ion. Potential sites are identified
and initially screened by county health department staff in most
instances. Identification of potential sites may result from
routine investigations of failing conventional systems, routine
disapprovals for new conventional systems, I/A grant program
public information meetings, or hearing decisions. Sometimes
potential sites are identified by direct requests from members of
the General Assembly * Potential sites that. have been screened by
co-unty health department staff' and recommended for further study
generally undergo a detailed site evalua,tion by OEP_before final
selection and accepta-nce an the program. Evaluations include
review of available data, making detailed soil descriptions and
conducting tests to measure soil permeability. The data are then
reviewed by OEP and county health- departments and a final
decision is made. If potential sites are eligible for I/A
grants, additional office screening and prioritization rankin-g
may be necessary to determine if a grant can be a-darded. In
either case, the property owner will also receive a letter report
that contains:

1. Preliminary Design Criteria

2. Design and Construction Guidel ines

3. Requirements for Submission of Plans and Specifications

4. Typical System Layout, Cross Section and Details

5. Monitoring Requirements

6. Legal Agreement

Over 273 screening and detailed site evaluations have been
conducted since FY 1981. Table I presents the number o-f
detailed evaluations conducted by OEP each fiscal year, including
the current fiscal year.

Page 12

Table I

Number of Detailed Site Evaluations

Fiscal Year Total Number

1981 2
1982 28

1983 48

1984 80
1985 20
1986 73
1987 17

It is expected that the number of evaluations for FY 1987 will
exceed all previous years.

Design and Construction If a property is selected, the owner
must have a consultant design the system and prepare the plans
and specifications according to the information contained in the
letter report. The plans are then submitted to OCEP and local
county heal th department for review. The initial design review
general 1 y resul ts in a need for at least one mee ting , a
submission of revised plans and a final approval letter. Larger
systems often require several design reviews, meetings, revisions
of plans and letters.

After final approval of the plans and specifications, the owner
must hire a qualified, contractor. If the owner was selected for
an I/A grant, at least two and preferably three cost estimates
must be obtained from contractors in order to select the best
bid. County health departments have been primarily responsible
for construction inspections in order to determine that systems
are constructed according to the plans and specifications. This
can be a very time consuming and critical activity in the overall
process. Four separate inspections may be necessary and in some
instances a continuous inspection may be necessary. Over 100
design reviews have been conducted and 9 systems have been
instal led or are currently under construction. OEP staff assist
with construction inspections when grant money is involved.

Soil Laboratory Analyses. Particle size analyses of sand samples
are performed by OEP staff to identify potential suppliers of
sand fill for construction. A total of 31 analyses have been
conducted.

Monitoring. Monitoring requirements are somewhat different for
each basic type of experimental system. Monthly visits are
generally required and may include:

1. Visual observations

2. Checks of flow meters, event counters, pretreatment and
pumping components

3. Measurements of effluent levels and water table levels

4. Sampling of pretreatment components, observation pipes,
monitoring wells or other monitoring devices

5. Homeowner interviews.

County health departments in the past have'been primarily
responsible for monitoring systems. In FY86,..two sani ta rians and
one environmental health aide were added to the OEP staff and are
assisting with monitoring. Currently, 20 systems are being
monitored on a monthly basis by OEP. During FY87, it is
estimated that an additional 30 systems will be added for a total
of approximitely 50 systems monitored by OEP on a routine basis.

Problem Investigations. Problems with experimental systems have
developed and require thorough investigations to determine the
cause and to propose potential so-lutions. Both OEP and I ocal
county health departments become involved in these
investigations. Fourteen problem investigations have been
conducted since FY85.

Technical Assessment* All available data from EPA, other States
and the program in Maryland are assessed to determine if the
experimental systems are satisfying evaluation criteria.
Depending on the results, the systems may be recommended for
conversion to conventional technology and final guidelines may be
developed.

Training Programs Training programs for county health
department staff fo improve site evaluations and perform design
reviews and construction inspections are ongoing and are provided
primarily by OEP staff. Site evaluation workshops have been
conducted in FY84, FY85, and FY86 providing training to over 122
sanitarians. Special training seminars were presented to five
local health departments. OEP staff members also participated in
five one-day groundwater protection seminars throughout the
State. OEP, with assistance from the Maryland Environmental
Training Center, is presently developing ten design and

Page 14

construction workshops for county health department staff,
consultants and contractors. Workshops are planned for January,
February, March and May in four locations around the State.
Contractor workshops in May will be part of a contractor
certification program also being developed by OEP as required by
COMAR 10.17.02.

Regulation Development. This activity is ongoing and is the
responsibility of OEP staff. Regulation development to date has
involved minor changes for clarification to existing regulations
(COMAR 10.17.02.06) ; new regulations for grant programs
(10.17.16); and major changes to existing regulations to
incorporate new conventional on-site technology

Grant Program Management. This activity is ongoing and is shared
among OEP, county health department, and county government
staff. Major activities completed by OEP have involved
developing State to County Model Agreements, County to Applicant
Model Grant Agreements, and prioritization ranking criteria.
Presentations to county government officials, planning meetings
and public information meetings are other activities that have
been conducted primarily by OEP and county health department
staff.

Eight counties are currently included in the grant program.
These counties are:

1. Anne Arundel
2. Kent
3. St. Mary's
4. Washington
5. Allegany
6. C e c i l
7. C h a r l e s
Wicomico

Four additional counties are under consideration for inclusion in
the grant program. These counties are:

1. Harford
9. Carroll
3. Dorchester
4. Garrett

PRELIMINARY FINDINGS

TECHNICAL ISSUES

Six major technical issues related to the increased use of both
conventional and experimental on-site systems have been
identified. Experimental efforts of the program attempt to
address and resolve these issues.

*Site Limitations

Site limitations within Maryland that are being addressed by the
program have been divided into four categories.

Permeable Soils with High Water Ta-bles. This category includes
soil and geol gic materials that have per-colation rates faster
than 60 minutes/inch, with water tables that are two to six feet
below land surface.

Shallow Permeable Soils Over Fractured Bedrock.' This Category
includes soil and geologic materials that have percolation rates
faster than 60 minutes/inch, with at least one to two feet of
suitable soil over fractured pervious bedrock.
Slowly Permeable Soils with H.igh Water Tables. Thi-s category
includes soil and geologic materials that havF percolation rates
between 60 and 120 minutes/inch.and water tables that are two
feet or more below land surface,

Very Slowly to Nearly Impermeable Soils. This category includes
soil and geologic materials that have percolation rates slower
than 120 minutes/inch. In certain Coastal Plain soil-
hydrogeologic environments, very slowly to nearly impermeable
soils are underlain by saturated sands and deeper confining clay
layers. If the surficial saturated sand aquifer has a low
potential for use as drinking water and discharge of partially
treated sewage *effluent to the aquifer will not cause
contamination of deeper aquifers or surface waters, oh-site
sewage disposal systems may be suitable. This special site
limitation category is being examined in more detail under the
provisions of the groundwater protection reports (GPR) required
by COMAR 10.17.02. The experimental systems that are being
evaluated for these types of soil-hydrogeologic environments are
discussed in this report under the sections involving groundwater
penetration syntems. Appendix B contains aeditional information
on the GPR requirements.

Page 16

*Adequa te Treatme7t

Conventional on-site sewage disposal systems generally consist of
a septic tank and a subsurface soil absorption system. T r 1= a tm, e n I..
of sewage occurs in the septic tank and in the soil in a properly
operating system. In order to accept the septic tank effluent'.
and provide adequate treatment, I:.*--- soil must be sui 4%,.abl e.

The bulk of available data and research indicates a t-do- to four-
foot depth of suitable, unsaturated soil material below the
bottom of s.ystems will prrvide a high degree of treatmant of
septic tank effluent. it has be!5n r@aported that aLmost, complete
removals of COD, BOD, suspended solids, phosphorus and bacterial
contaminants can be achieved. Data to support similar reduction
of viruses are not as conclusive. Removals and inactivation oil
viruses are more variable and depend on the type of virus an", a
number of conditions such as Soil clay content, organic matter,
pH, moisture content, and residence time in the soil.

Other chemical constituents such a; nitrogen, exchangeable
cations, chlorides*, sulfates, other anions and trace organics
undergo various reactions in the soil treatment zone and may be
attenuated to different degrees. Many of'these chemical
constituents are not attenuated to any great extent a7nd over t-imie
will move downward with soil waters and mix with underlying
groundwaters. Increases in total dissolved solids, chlorides and
nitrate-nit.rogen of groundwaters may be experienced. The
s.ignificance of these impacts and the resulting degradation of,
groundwater quali-ty becomes more, important, as densities of or, '-
site systems increase. Cumulative effects of im-pacts from, cn-
site sewage disposal-systems and other sources of contamirzn@s
associated with suburban land use have produced significant
groundwat-er pollution in some areas aiong the east coast.
Presently, it appear's that nitrate-nitrogen is the cons 16, i t of,
inost concern.

Soil Treatment Zones., In COiMAR 10.171.02, the State has adcpted
the use of a four-foot soil treatment zone for conventional on-
site systems. This soil treatment zone not. only provides a high
degree of treatment, but incorporates two additional practical
considerations. These involve the difficulty of estimating
accurate depths to high groundwater based on minimal observations
and typical installation p-obleiiis that can often result' in actual
treatment zone depths being less than design depths. Use of a
four-foot treatment zone allows for a reasonable margin c4 safety
w
hen considering the practical limitations of evaluating sites
and installing conventional systemns.

The use of two- to four-foot soil treatimert zores and practical
limitations of construction are being investigated in the
program.

Groundwater Penetration.* Hany areas within the Maryland Coastal
Plain province have s nally, high water tables at depths that
cannot provide a four-foot treatment zone below the bottom of on-
site disposal systems. Previous regulat.ions have allowed Talbot,
Dorchester, Wicomico, Somerset, and Worcester to discharge septic
tank effluent directly to surficial groundwater aquifers under
certain conditions. This practice has been referred to as
groundwater penetration and is; used routinely in these counties.

Local county health departments that routinely use groundwater
penetration have not associated any major public health problems
with these systems. Extensive! monitoring and well documented
studies of the impacts of these systems..on groundwater or surface
waters, however, have not been conducted.- The use of groundwater
penetration systems that provide better treatment and nitrogen
reductions are being investigated in the 'program. In addition,
sufficient data regarding the design of these type systems is
also being collected.

*Construction Practices

In almost all cases, innovative and alternative systems are more
complex and require more detailed construction steps and
management. Specifications and routine achievement of two-foot
treatment zones during construction may not be practical without
intensive contractor training and intensive construction
inspection.

This issue needs to be assessed as part of the experimental
ef fort and may become the most important i ssue in deciding
whether or how experimental systems are converted to conventional
use.

*Equipment Problems

Since many of the innovative and alternative systems are sited on
property with high water tables or fractured bedrock, septic
tanks and pumping chambers must be water-tight. Existing tanks
and chambers in many instances are not adequate and have caused
problems. Improvements in tanks and equipment are needed to
resolve these problems.

*Operation and Maintenance Innovative and alternative systems in
almost all instances are more complex and involve more operation
and maintenance requirements than conventional systems. -The
actual success or failure of some experimental systems may depend
directly on homeowner maintenance. Past experience indicates
that many homeowners do not perform the minimal maintenance
requirements associated with existing conventional systems and in
some instances do not understand their basic function and
operation.

Page 18

Homeowner educational programs need to accompany installation of
experimental systems in order for the homeowner to understand:

- the basic function and operation of the system

how to perform routine maintenance requirements

- how to recognize warning signs that may indicate developing
problems or possible malfunction, and

- the costs that will be associated with increased 0EM
r equ i r emen t s .

Homeowner performance of routine maintenance con then be assessed
more objectively in the experimental effort.

*Management of On-Site Systems

An alternative to homeowner responsibility for maintenance of
more complex on-site systems is to have a management entity
assume this responsibility. Performance of necessary maintenance
by a management entity could assure higher confidence that a more
complex on-site system would operate properly and meet basic
public health and environmental criteria. This approach involves
a number of institutional and legal problems. The existing CEP
staff cannot examine and resolve these problems.

SYSTEM UNDER EVALUATION

This section describes the experimental systems under
evaluation. Available data, guidelines, and regulations frcm EPA
and other states were -reviewed and used along with data collected
in Maryland. Systems that incorporate soil treatment zones and
that discharge directly to groundwater (i.e., groundwater
penetration systems) are presented along with solar systems.

Pace 19

*Soil Treatment Systems

Systems in this category incorporate soil treatment zones between
a limiting zone and the bottomof absorption beds or trenches.
The treatment zones range in thickness between two and four
feet. Where soil treatment zones do not exist naturally, they
can be achieved by constructing:

- sand mounds above the natural soil surface,

- shallow trenches near the soil surface, and

sand fills that have replaced unsuitable soil materials.

Designs generally incorporate pressure dosing to provide:

uniform distribution which utilizes the entire volvne of the
absorption bed or trench

dosing and resting cycles which maintain unsaturated soil
conditions resulting in aerobic pores and less restrictive
clogging mats
Designs,may also incorporate up-slope inierceptor drainage to
help achieve adequate soil treatment zones above high water
tables.

Sand Mound. This system consists-of a double-compartment septic
-tank, pump, pumping chamber and an absorption bed elevated above
the natural soil surface in a suitable sand fill. Septic tank
effluent is pumped into the bed through a pressure distribution
network. Treatment occurs as effluent moves downward through the
sand fill and into the underlying soil. This system has been
studied intensively by a number of investigators and states
throughout the country (4, 5, 6, 7, 8, 9, 10, and 11). The
Wisconsin site criteria and design is the most accepted and is
currently used in this program with two modifications. A
cylinder infiltrometer test, that estimates vertical
permeability, is used instead of a percolation test and the sand
fill specifications are more restrictive. It has been reported
that these systems can overcome the following site limitations:

1. Permeable Soils with High Water Tables;

2. Shallow Permeable Soils Ove-. Fractured Bedrock;

3. Slowly Permeable Soils.

Page 20

ltinet,een systems are currently under evaluation in the prograr....
Sixteen systems are on perimeable soils with high water tables and
three are on slowly permeable soils. The systems on permeable
soils with high water tables have performed well and generally
confirm available data. In 1986, the first step in c-ctiverting
sand mound systems to conventional use was taken. Sand rounds
for permeable soils, with percolation rates less than 300
rilinutes/inch and high water tables two feet, or deeper, were
included in COMAR 10.17.02 as conventional sys'eims. Two systemis
on the slowly permeable soils are under-utilized and the third is
currently experiencing mechanical problems. Results for slowly
permeable soils are therefore not' conclusive at this tire.
Additional mound systerns on slowly permeable soils are needed to
help answer question-, regarding soil damage and ccmpaction during
construction and the possible use oil up-slope interceptor
drainage on sloping site-s to divert perched water.

Shallow Pressure Dosing Trench, This system consists of a
double-compartment septic tank, pump, pumping chamber and soil
absorption trenches. The trenches generally range bet-ween 0.5
and 2.0 feet in width, 1.0 to 1.5 feet in depth and are excavated
with a ditch-witch. This systein has been studied prinnarily by
North Carolina and several other states. This system allows
shallow placement in the soil to maintain "two feet oi: greater
treatment zones below the bottom of trenches. Pressure dosing
provides uniform distribution of effluent throughout the trenches
and dosing and resting cycles. It has been reported that these
systems can overcome the following site limitations:

1. Permeable Soils with High Uater T a b 1 e s

2. Shallow Permeable Soills Over Fractured 31eJrock

3. Slowly Permeab'le Soils

Over forty-four of these systems have been installed or are under
construction. Six systiins are currently under evaluation in the
program. Thirty-eight*systems were installed in the Harney
Project in Carroll County and were evaluated by consultants.
Four out of the six systems being evaluated by the State,
experienced construction related problems with one chronic
failure occurring. Additional study of systems installed in
Harney and other locations throughout the State is planned.
Treatment cap:bility, groundwater mounding and freezing problems
that have been reported by other States will be evaluated. On
sloping sites, up-slope interceptor drainage to divert perched
water tables will also be studied.

Sand Lined Pressure Dosing Trench. This system consists of a
double compartment septic tank, pump, pumping chamber and soil
absorption system constructed in sand fill. Two-foot treatment
zones will be used. -These syst-ems can only be used where

I- __ - - n't

underlying soils are sandy and wi,ll not be damaged by
construction. This system is similar to sand lined systems that
are installed in Delaware and Pennsylvania. This system is
designed to overcome the following site limitations:

10 Very Slowly to Nearly Impermeable Soils

Permeable Soils Over Fractured Bedrock
2.
o

30 Slowly Permeable Soils

No systems are installed at this time. Plans are underway to
have systems constructed in 1987, Evaluation of treatment
capability and construction methods will.be undertaken.

Alternating Fields. This system consist5. of a double-compartment
septic tank, diversion valve and two soil absorption fields.
Wastewater is diverted to each field alternately, allowing one to
rest and be rejuvenated by biodegradation of the clog-ging mat.
It has been,reported that this system will extend the design life
of the soil absorption field and would allow each field to be
designed with 25% less effective soil absorption area. Very
little data are available to support this claim. These systems
are being evaluated to overcome site limitations of- slowly
permeable soils.

One system is being evaluated and pl ans. for additional systems to
be installed are underway.
*Groundwater Penet;ation Systems

These systems are constructed to discharge directly to surficial
groundwater. They are similar- to conventional groundwater
penetration systems with the exception that they are designed to
provide better treatment of effluent before it is discharged.
Areas in the Coastal Plain where these types of systems may be
utilized are to be further evaluated through the process of
preparing "Groundwater Protection Reports" (GPR's) recently
required in COMAR 10.17.02.

Sand Lined Trench. This system consists of a double compartment
septic tank and soil absorption trenches. The trenches are
constructed to discharge directly to groundwater but are
backfilled with sand fill instead of gravel. The trenches may be
elevated above the original land surface in an impermeable fill
in order to obtain adequate hydraulic head for performance when
the water tableis high. This system has been used in Ifiryland
to overcome site limitations of permeable to nearly impermeable
surface soils with high water tables.

Page 22

Hundreds o f these systems have been installed in the past on the
eastern shore coastal plain. The majority are in parts of
Worcester, Dorchester, Somerset, and Talbot counties. Two
systems are being evaluated in this program -with plans to include
more. Treatment capability and design criteria are being
s t u d i e d .

Sand Filter Trench. These systems consist of a double-
compartment septic-tank, pump, pumping chamber, sand filter and
soil absorption trenches. Designs include buried, free-access
and recirculating sand filters that incorporate a* variety of
modifications to reduce nitrogen, phosphorus and fecal
coliforms. These systems are designed to overcome limitations of
high ground -dater.

Seven systems are under evaluation with plans to install more.

Bermed Infiltration Pond. A bermed infiltration pond is an
excavation approximately eight to ten feet deep with no less than
10,000 square feet in surface area. The excavation exposes a
water-bearing substratum sand overlain by an impermeable soil.
Part of t-he excavated materia-1 is placed around the pond
perimeter to form a berm. The water from the substr-atum rises
and falls in the pond in accordance with seasonal fluctuations ir.
the water table. Septic tank effluent is discharged near the
bottom of the pond, for disposal. The biological organisrns in the
pond complete the treatment process and the water -moves into the
surficial groundwater surrounding the pond or evaporates.

Over fifty of these systems have been installed in the E3stern
Shore Coastal'plain, primarily in Dorchester County. They are
reported to perform well and are proposed to be converteda into
conventional use by 'the end of 1.987. A few quest-ions regarding
design and constructflon of small systems remain to be answered.
Larger systems, involving more than three homes per pond, are
still under study and wi-11 not be converted to convent-ional use
by the end of 1987.

*Solar Systems These systems are for the most part independent
of soil conditions and therefore theoretically would overcomne all
site limitations. They consist of a double-compartment septic
tank or aerobic tank with discharge enhanced by evapotranspiration
within a greenhouse unit. Two basic types have Leen identified,
but only one type is being evaluated. Four systems have been
installed. Dat'a collected in 1985 indicated major problems with
these systems. In addition the systems appear economically
prohibitive. A contract with the University of Maryland was
entered into in August 1986 to perform a more thorough technical
evaluation. The final report is due in July 1987 and will
provide information for future direction.

STAFF REQUIREMENTS

The extra staff time associated with the I/A program and the
conversion of sand mounds to conventional use is impacting and
will continue to impact county, health department programs and
services. Table 2 provides our best estimate of staff time
required per system to perform work tasks associated with the I/A
program and conventional sand mounds. Actual staff requirements
related to the I/A program are! difficult to estimate. Program
goals are to have ten to 15 experimental systems per basic
category. Based on this goal and past acceptance rates into the
experimental program of ten to, 30 percent (i.e., ten to 30
percent of all sites evaluated for the-:I/A program are accepted
for experimental' studyl and four hours actual work time per day,
approximately 0.5 to 1 .'5 man-years are re..qui red to perform the
estimated work in each 1-ocal health department that is active in
the I/A program.

After a two- to three- year period, this work load would drop.
However, the conversion of IIA technology to conventional use is
expected to increase staff requirements substantially.

Page 24

Table 2.' Estimated -Staff Time Required Per Systeml

Conven'-ional Innova tAve/ AI t e r n a t i v
Task Sand 'Alo"und Procram

Per System - - - - - - - - -
Ireening Site Evaluation 2 - 3 2 - 3

tailed Site Evaluation 4 - 8 4 - 8

Design Review 5 - 10 7 -
Instruction Inspections 4 - 12 0 - 12
nitoring2 ------ 48 - 72

We expect staff time required to perform tasks to approac C W
estimates with experience.

Mlonitoring estimates are based on v1sit: ye2rs
and do not include travel time to i t9

PROBLEM INVESTIGATION

Fourteen problem investigation have been conducted.' Eight
involved construction related problems and only one of these
appears to have resulted in chronic system failure. Two of the
construction problems involved sand mound systems; four involved
shallow placement - low pressure pipe systems; one involved an
enhanced evapotranspiration systems; and one involved an
alternating Iield system. The apparent chronic failure involving
a shallow placement system is believed to be a construction
problem but conclusive evidence is not available,

Equipment problems were observed on two.systems. These involved
leaking septic tanks and a pump failure.

The remaining four problems were related to design. One of these
problems is bei.ng corrected, the remaining three are still under
study.

Page 26

CONCLUSIONS

Based on the preliminary findings, the following conclusions
are presented:

I. Construction related problems that have been experienced
appear to be caused by two factors. One is on insufficient
number of inspection visits by local county health
department staff. The other is the lack of contractor
familiarity and experience installing more complex
systems. These types of problems are also indicative of
problems that could develop i f experimental systems ore
converted into conventional technology without adequate
staff to perform the inspection work, and insufficient
training of both local county health department staff and
contractors.

2. Sand mound systems designed on permeable soils (less then 60
minutes/inch infiltrameter rates) with high water tables and
over fractured rock could be converted to conventional
technology in 1987. However, the additional staff time
involved in detailed site evaluations, design reviews and
construction inspections' will increase current workloads of
almost all local county health departments, especially
during wet season testing periods.

3. Continued experimentation and data collection is needed for
all systems currently under evaluation, except sand mounds
on permeable soils, before final decisions con be made.

4. Almost all of the systems under evaluation are more complex
and costly than conventional systems. They also require
increased homeowner responsibility and understanding.
Educational programs need to be developed or adapted from
other States to provide the homeowner with an understanding
of the systems that are converted to conventional use.

5. It should be noted that OEP's next technology approval is
slated for July 1987 and consists of extending percolction
rates to 60 minutes for sand mounds. We also anticipate
approving bermed infiltration ponds as conventional
technology and making a final decision on the use of the
solor system. By December 1987, OEP expects to have enough
operating data on sand-lined trenches employing groundwater
penetration to have completed design criteria which could be
uniformily applied to all Coastal Plain Counties. This
criteria will be subsequently included in Regulation
10.17.02 which should be finalized within an additional four
to six months.

Page 27

RECOMMENDATIONS

Based on the preliminary findings and conclusions, the
following recommendations are presented for consideration and
action:

1. A seven member advisory task force, composed of a contractor
and university and consulting soil scientists,
hydrogeologists and engineers should be formed to advise the
State on future program direction regarding research needs,
homeowner educational programs and on-site system community
management.

2. The current classification of on-site sewage disposal
systems known as Innovative and Alte@rnative is proposed to
be divided into two categories:

Innovative

Alternative

Innovative systems would be those systems that are considered
experimental or have not been satisfacto'rily evalua-ted under site
conditions found in Maryland.

Alternative systems would be those systems that have been
demonstrated to function satisfac-torily but require more detailed
site evaluation, system design-.and more intensive construction
inspections than would normally be expected for conventional on-
site systems.

The installation of alternative systems may be limited to certain
times of the year with favorable soil moisture conditions and
weather. They would also require extraordinary measures to be
taken to prevent damage to soil absorpti-on areas during
construction on the site. Procedures for permit issuance and
design review and construction need to be investigated. Permit
authority for some systems at the State level with subsequent
delegation to counties with acceptable programs should also be
investigated.

This new category would also help facilitate homeowner education
regarding increased responsibility, maintenance and risks
associ3ted with these types of' systems.

Page 28

PROPOSED DECISION SCHEDULE

Rq*rimenta. I YEAR
System 1987 1980 1989 1990 1991 1992

Soil Treatment Systems

Sand Mound
Permeable Soils
Slowly Permeable Soils
Shallow Pressure Dosing Trench
e--. is
Perrnec-wt-lle
Slowly Permable Soils
Sand Lined Pressure Trench
Alternating Fields 2

Groun&jater Penetration
systeffts

Sand.Lined Trench
Sand Filt..;r Trench 13
Berined Infiltration Pond

Fnhanced Evapotranspiration
SysLem

1. Potential f rcezing, grom)-oter 1lXA-.'di11fJ illfl ilr-AM ]%d i0i tVd1niqxK.--, are. lx-,iiyj investiqateA.
20n) ie e-yreritivatal systco presetitly iir;.tA%11v%1 in Mir/).ud @,wilwtitxj ny--t(w IcA'squlaiLy rc<pircs yvars of che;ervaLil -

3
.. %ral differr.nr 1, trot ol providiryl for nitro,-on rtitf)v.)l ',tjt/7

DATE DUE

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