[Federal Register Volume 59, Number 127 (Tuesday, July 5, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-16220]
[[Page Unknown]]
[Federal Register: July 5, 1994]
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Part II
Environmental Protection Agency
_______________________________________________________________________
Sole Source Aquifer Designation of the Vashon-Maury Island Aquifer
System, King County, Washington; Notice
ENVIRONMENTAL PROTECTION AGENCY
[FRL-5006-8]
Sole Source Aquifer Designation of the Vashon-Maury Island
Aquifer System, King County, Washington
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final determination.
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SUMMARY: The Region 10 Administrator of the Environmental Protection
Agency (EPA) has determined that the Vashon-Maury Island Aquifer System
is a sole or principal source of drinking water, and if contaminated,
would create a significant hazard to public health. This action was
taken under the authority of section 1424(e) of the Safe Drinking Water
Act in response to a petition submitted to EPA by the Seattle-King
County Department of Public Health on April 2, 1992. As a result of
this determination, all federal financially assisted projects proposed
in the designated area will be subject to EPA review to ensure that
they do not create a significant hazard to public health.
EFFECTIVE DATE: This determination shall be promulgated for purposes of
judicial review at 1:00 p.m. Eastern time on July 19, 1994.
ADDRESSES: The information upon which this determination is based is
available to the public and may be inspected during normal business
hours at the EPA Library, 10th Floor, Park Place Building, 1200 Sixth
Avenue, Seattle, Washington 98101.
FOR FURTHER INFORMATION CONTACT: Scott E. Downey, Environmental
Protection Specialist, Ground Water Section, WD-133, U.S. Environmental
Protection Agency, Region 10, 1200 Sixth Avenue, Seattle, Washington
98101, 206-553-0682.
SUPPLEMENTARY INFORMATION: This action is being taken under the
authority of section 1424(e) of the Safe Drinking Water Act (42 United
States Code, 300f, 300h-3(e), Public Law 93-523). The information upon
which EPA is issuing this final determination has been summarized in
the ``Support Document for Sole Source Aquifer Designation of the
Vashon-Maury Island Aquifer System'', EPA 910/K-94-002.
I. Background
Section 1424(e) of the Safe Drinking Water Act states:
If the Administrator determines, on his own initiative or upon
petition, that an area has an aquifer which is the sole or principal
drinking water source for the area and which, if contaminated, would
create a significant hazard to public health, he shall publish
notice of that determination in the Federal Register. After the
publication of any such notice, no commitment for federal financial
assistance (through a grant, contract, loan guarantee, or otherwise)
may be entered into for any project which the Administrator
determines may contaminate such aquifer through a recharge zone so
as to create a significant hazard to public health, but a commitment
for federal assistance may, if authorized under another provision of
law, be entered into to plan or design the project to assure that it
will not so contaminate the aquifer.
Although EPA has the authority to initiate ``sole source aquifer''
designations, the Agency has a policy of acting only in response to
petitions. Petitions may be submitted to EPA by any individual or
organization and must address procedures and criteria outlined in EPA's
``Sole Source Aquifer Designation Petitioner Guidance'', EPA 440/6-87-
003.
On April 2, 1992, EPA Region 10 received a petition from the
Seattle-King County Department of Public Health requesting that EPA
designate Vashon-Maury Island as a sole source aquifer. The petition
was developed in cooperation with the Vashon-Maury Island Ground Water
Advisory Committee and the Vashon-Maury Island Water Utilities
Coordinating Committee. Recognizing the value of the aquifer as a
present and future source of drinking water, the petition was submitted
as an additional way to protect the Island's ground water resources.
EPA's initial review of the petition led to a request for
additional hydrogeologic and water usage information. This information
was subsequently submitted to EPA by the petitioner. On October 21,
1992, the petition was considered complete enough to undergo a more
detailed technical review. The technical review was completed in April
of 1994 and EPA's findings and basis for the proposed designation were
documented in EPA's Support Document.
II. Basis for Determination
The Region 10 Administrator has determined that the Vashon-Maury
Island Aquifer System meets all applicable sole source aquifer
designation criteria established through Federal statute and EPA
guidance documents, as follows:
(1) Sole or Principal Source of Drinking Water: Sole source
aquifers must supply at least 50 percent of the drinking water to
persons living in the area overlying the aquifer and in areas supplied
by the aquifer. The Vashon-Maury Island Aquifer System supplies
approximately 71 percent of the drinking water to persons living on the
Island.
(2) Potential Public Health Hazard: Contamination of the sole
source aquifer must create a significant hazard to public health. As
the principal drinking water source for the area, contamination of the
Vashon-Maury Island Aquifer System would create a significant hazard to
public health.
(3) Definable Aquifer Boundaries: EPA guidance allows designations
to be made for entire aquifers, hydrogeologically connected aquifers
(aquifer systems), or part of an aquifer if that portion is
hydrogeologically separated from the rest of the aquifer. The Vashon-
Maury Aquifer System boundary is based on hydrogeological principles
and EPA's interpretation of available data. The Island's hydrogeology
is representative of an aquifer system, as data indicate that water
from shallow aquifers infiltrates to underlying deeper aquifers. The
sole source aquifer boundary is coincident with the shoreline of the
Island, and at depth includes all geologic units that can supply
significant quantities of drinking water to wells. This boundary is
assumed because stratigraphic data are not available to fully map the
vertical extent of the aquifer materials.
(4) No Alternative Source of Drinking Water: There can be no
physical, legal, or economically feasible alternative source(s) of
drinking water of sufficient volume that could replace the sole source
aquifer, should it become contaminated. EPA has determined that there
are no reasonably available alternative source(s) of drinking water
that could replace the aquifer.
III. Description of the Vashon-Maury Island Aquifer System
Note: Information in this section represents an unfootnoted
summary from EPA's Support Document, EPA 910/K-94-002.
Vashon-Maury Island is located near the southern end of Puget Sound
in the southwestern corner of King County, Washington. The Island
covers an area of 36.7 square miles and its population has been
estimated at approximately 7,800 persons. Recorded data indicates an
average rainfall of 46.53 inches.
The aquifer system is composed of both interbedded glacial and non-
glacial deposits. In general, the water table elevation reflects the
surface topography and the ground water moves radially outward from the
interior to the shorelines of the Island.
The uppermost and most recent deposits (Quaternary Vashon unit) are
mainly stratified sand and gravel overlying glacial till and sandy
gravel interbedded with medium and fine-grained sand. The Vashon unit
contains a surficial aquifer comprised primarily of glacial till which
has poor water-bearing characteristics, and the uppermost fresh water
aquifer (Principal Aquifer) comprised of outwash sand and gravel beds.
The Principal Aquifer is found at an elevation of between 0 and 400
feet above mean sea level. Recharge of the Principal Aquifer is
probably highest along a north-south corridor of west-central Vashon
Island, and is estimated to be approximately 9 million gallons per day.
The Principal Aquifer supplies ninety-five percent of the wells located
on the Island.
Underlying the Vashon unit are non-glacial deposits (Quaternary
Olympia beds) generally consisting of thin-bedded sand and silt with
local layers of gravel, massive silt and clayey silt. The Olympia beds
serve as a leaky aquitard between the upper Principal Aquifer and the
lower Deep Aquifer. The Deep Aquifer underlies the Olympia beds and
consists of a variety of interbedded glacial tills, sand and gravel
units and laminated silts and clays. The Deep Aquifer is located at an
elevation of between about 100 to 300 feet below mean sea level.
Recharge to the Deep Aquifer is estimated at between 1.73 and 3.46
million gallons per day.
Ground water quality data was sampled from 72 wells in the aquifer
area. In general, deeper wells exhibited higher specific conductance
values. Elevated chloride concentrations were found in near-shore wells
on the northern and eastern edges of the Island. Ground water quality
trend data is limited, but combined water system and spring data
indicate that source water nitrate concentrations show a generally
increasing trend.
The sand interbeds within the surficial glacial till deposits allow
easy infiltration, and although discontinuous, make much of the
Principal Aquifer vulnerable to contamination. The Deep Aquifer is also
vulnerable to contamination from activities occurring on the land
surface, as evidence suggests that it receives recharge from the
Principal Aquifer.
Potential sources of contamination include landfill leachate, on-
site sewage disposal systems, leaky sewer lines, underground storage
tanks, agricultural chemicals, small hazardous waste generators,
accidental spills, seawater intrusion, and improper household, forestry
and farm practices.
The Island has one publicly-owned water well (the largest water
system on the Island), at least six large private water systems, and
more than 100 smaller water systems. Some purveyors use both surface
water and ground water to supply their distribution system. In
addition, private wells provide water to a considerable number of
houses and businesses across the Island. It is estimated that 71% of
the water supplied to households on the Island is from ground water and
29% is from surface water sources. There are no alternative sources of
drinking water for the Island that can be physically, legally, and
economically supplied.
IV. Project Reviews
Designation of a sole source aquifer authorizes EPA to review
federal financially-assisted projects proposed within the designated
area. The principal mechanism used by EPA Region 10 to identify
projects for review are Memorandums of Understanding (MOUs) with
federal funding agencies. These MOUs outline procedures for screening
and referring projects to EPA in order to ensure that only projects
which may have a significant impact to ground water quality are
reviewed.
Most projects referred to EPA for review meet all federal, state,
and local ground water protection standards and are approved without
any additional conditions being imposed. Occasionally, site or project-
specific concerns for ground water quality protection lead to specific
recommendations or additional pollution prevention requirements as a
condition of funding. In rare cases, federal funding has been denied
when the applicant has been either unwilling or unable to modify the
project.
Whenever feasible, EPA coordinates the review of proposed projects
with other offices within EPA and with various federal, state, or local
agencies that have a responsibility for ground water quality
protection. Relevant information from these sources is given full
consideration in the sole source aquifer review process. Such
coordination can complement, support, and strengthen existing ground
water protection mechanisms.
V. Public Comments
EPA issued a news release (April 12, 1994) and a public notice
(April 14, 1994) to request comments and announce the proposed
designation. Both stated that a public hearing would be held if
sufficient interest were expressed to EPA in advance. No requests for a
formal hearing were received and it was subsequently cancelled.
Five written comments were received prior to the expiration of the
public comment period on June 1, 1994. Three letters were from Vashon
Island residents and expressed support for the proposed designation.
One letter was from the King County Department of Public Works, Roads
and Engineering Division, and requested information and coordination of
future federal financially-assisted road projects on the Island.
Another letter was from the Bureau of Reclamation and stated there were
no ongoing or proposed federal financially-assisted projects within the
area. No controversial issues were raised as a result of this proposed
action.
VI. Summary
This determination affects only the Vashon-Maury Island Aquifer
System located in King County, Washington. As a result of this
determination, all federal financially-assisted projects proposed in
the designated area will be subject to EPA review to ensure that they
do not create a significant hazard to public health.
Dated: June 17, 1994.
Chuck Clarke,
Regional Administrator, U.S. Environmental Protection Agency, Region
10.
[FR Doc. 94-16220 Filed 7-1-94; 8:45 am]
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