Monomoy lens focus on : Harwich groundwater protection

8 Pages·1998·0.48 MB·English

by  Cape Cod Commission. Water Resources Office

Monomoy
Lens
HARWICH
Focus on:
Groundwater
Protection
^ ^
B MM. UMASS/AMHERST
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Prepared by the
Water Resources Office
Cape Cod Commission
for the Harwich Water Department
This map shows the MonomoyLenswater
table in10 footcontourintervals.
January 1998
2
Wliat's this pamphlet all about?
CapeCodisfortunatetohaveanabundantsupplyofhigh
qualitydrinkingwater. Thisbrochureanswersfrequently
asked questions about groundwaterand discussespoten-
tial impacts from population growth on drinking water
supplies. The information in this brochure is intended to
familiarize residents of the town of Harwich with local
drinking water supply sources and what isbeing done to
ensure they will remain safe for years to come.
Wltere does the water supply originate?
The Monomoy Lens is the source of fresh water for the
town ofHarwich. This lens is one ofthe six groundwater
lenses that make up the Cape Cod Sole Source Aquifer.
Lenses can be thought of as mounds of groundwater
bordered by marine water at the edge, bedrock on the
bottom, and separated from each other by tidal waters,
suchastheBassRiver, thatcutacrosstheCapepeninsula.
Groundwater refers to subsurface water in soils and geo-
logic formations that are fully saturated.
Groundwater in the Monomoy Lens is replenished from
rainorsnow thatseeps intothe ground. Thewaterperco-
lates throughthe soiltoreachthewatertablewhichis the
surface of the groundwater lens. Water within the lens
slowlymovestowardthecoastwhereitdischargesintothe
ocean.Alongtheway,groundwaterflowsintothenumer-
ous kettlehole lakes and ponds, and into streams feeding
marine embayments along the coast.
The map on the next page shows the location of the
Harwich public drinking water supplies. The shaded
areas represent the land area where the groundwater
flowstowardthewellinsteadofmovingallthewaytothe
shore. These areas are referred to as recharge areas, well-
head protection areas, or, if state approved. Zone ITs.
Recharge areas forwells located inDennis, Brewster, and
ChathamthatcrosstheHarwichtownboundariesarealso
shown.
WaterResources Office - Cape CodCommission
3
Harwich Public Supply Wells
Wellhead ProtectionArea
#
PublicSupply Well
^
FutureSupply WellSite
How much water does Harwich use?
In1996,theHarwichWaterDepartmenthadtwelvewells
in operationthatpumped anaverage of 1,523,240 gallons
perdayprovidingwater to 12,000peopleyearround and
2,932,421 gallons per day to 36,000 people during the
summermonths.
Publicwaterservicesincludeover168milesofmain,8186
residentialhook-ups,and339commercial/municipalhook-
ups. An estimated 300 homes orbusinesses are supplied
by private wells.
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Is there enough water to supply the town
in thefuture?
TheHarwich waterdepartmentisalwaysintheprocessof
planning for future water supplies to meet its growing
needs andtoensurean adequatesupplyintheeventofan
emergencywellclosure. Currently,Harwichhasplansfor
two additional well sites which could provide an addi-
tional 1.5 million gallons/day. The following chart com-
pares water demand and supply for existing and future
conditions. The chart shows that based on current popu-
lation predictions Harwich can provide enough water to
its residents for the next twenty-five years. Additional
suppliesmaybeneededifthereisabigshiftfromseasonal
toyearroundresidentsorifmaximumdaydemandcondi-
tions continue for more than a few days. As iron and
manganese levelsincrease atvarious sites, treatmentmay
be necessary to improve overall quality and ensure con-
tinuance of an adequate supply.
Harwich Public Water Supply and Demand
1995 2020
10
^ 8^ I
? 7
^ 5
1
^
3^I I i
i
2
i
I 1
0 ^
to
.
Demand
(forplanningpurposesdemand
includeslossoflargestsupply)
Supply
Averageday-wellspumping 16hours
Maximumday-wellspumping24hours
(Maximumpumpingcanonlybesustained
forashorttime.)
5
Harwich Land Use Percentages
17%
Source: 1993Assessor'sdata
ED Residential ^1 Commercialdevelopable
Commercial/Industrial/ 1h1HI-nH Undevelopable
Agricultural
Residentialdevelopable Openspace/Conservation
[ 1
Hoiv can land use impact water supplies?
Thechartabove shows the distribution ofland use inthe
town.Openspace,whichcomprises17percentofthetotal
landareainHarwich,isbeneficialtoprotectpublicwater
supplies frompotentialcontamination sources.The town
is currently37percentresidentialand 9 percentcommer-
cially developed. One of the greatest threats to water
supplies is non-point source pollution from septic sys-
tems. Zoning bylaws protect these supplies by setting
appropriatesetbacksfromsupplywellsandlimitingsep-
ticsystemdensityinareascontributingtowatersupplies.
Watersuppliesmayalsobethreatenedfromimproperuse
anddisposalofchemicalproductsusedinhomesorbusi-
nesses.Stepstoeducateresidentsandbusinessesonproper
disposalofthesematerialsis thebestdefensefrompollu-
tion. Eachyear,thethirdSaturdayinJune,thetownholds
ahouseholdhazardouswastecollectiontohelpminimize
improper disposal of these materials. Recycling facilities
are available at the landfill for batteries, motor oil and
filters, antifreeze, and paint.
3225Main Street, Barnstable,MA 02630

6 7
Groiindivater Protection Regulations
REGULATEDBY:
WATERSUPPLY STATE COUNTY TOWN OF HARWICH
Drinking Water Protection District 310CMR22.21(2) RPP Zoning
Private Well Board of Health
WASTEWATER/NUTRIENTS
Individual Sewage Disposal Systems 310CMR15:00 DRI review Board of Health
Wastewater Treatment Plants 310CMR5.00 DRI review Zoning/Board ofHealth
NutrientLoading 310CMR22.21/15:00 RPP/DRI review Zoning
AnimalManures Zoning
HAZARDOUSMATERIALS
Toxic and Hazardous Materials 310CMR22.21 RPP Zoning
Floor Drains 310CMR22.21 Board of Health
UndergroundStorageTanks 527CMR9.00 Board of Health
Herbicides/Pesticides 333CMR Board of Health
CMR: CodeofMassachusettsRegulation RPP: RegionalPolicyPlan(CapeCodCommission)
Notregulated DRI: DevelopmentofRegionalImpact
Wimt actions have been taken to protect Witat else can he done to safeguardfuture
water supplies? supplies?
Thetableshownaboveliststhewaterresourceprotection There are several actions thatcanbe taken to strengthen
controls relating to wastewater and hazardous materials watersupplyprotectioneffortsinthetown. TheBoardof
that are enforced at the local, county and state levels. Healthcouldadoptatownwidehazardousmaterialregu-
Harwichhasmanygoodregulationsinplaceandisinfull lation which includes site inspection, registration, and
compliancewithstatedrinkingwaterrequirements.Well- inventory.
head protection is extended to the surrounding towns of
Dennis,Brewster,andChathamwhereZoneII'scrossinto In orderto reduce thenitrogen load from septic systems,
Harwich. minimum residential zoningcouldbe increased in zones
of contribution to public supply wells. The town should
Additionally, groundwater is protected by a variety of continue to purchase potentially developable residential
BoardofHealthregulationsrelatingtoprivatewells,com- landlocatedwithinexistingwellheadprotectionareasand
mercial floor drains, underground storage tanks, herbi- foruseas futurewellsites.
cides/pesticides, and on-site septic systems.
WaterResources Office - CapeCodCommission 3225Main Street,Barnstable,MA 02630
8
How
can I be sure that the water is safe
to drink?
Harwich'spublicwatersupplyistestedatleasttwiceeachmonth
forbacteria,andannuallyfornitrate-nitrogenandotherorganic
and inorganic compounds specified by state and federal stan-
dards. If any problems are encountered, law requires public
noticetobepublishedinalocalpaperandtheproblemcorrected.
Certified water operators are always available to provide cus-
tomers with copies of recent water quality results or to answer
specific questions.
Thewatersupplyisofexcellentqualityrequiringtreatmentonly
to control the natural acidity and periodic chlorination when
cleaning the tanks. Average nitrate-nitrogen concentration for
the Harwich public supply wells is presently 0.73 parts per
millionwhichiswellbelowthestateandfederallimitof10ppm.
Private well water quality is the responsibility of individual
property owners and should be tested regularly. Private wells
may experience aesthetic problems such as staining and odor
from high concentrations of iron or manganese. High levels of
sodium, from salt water or road salt, are occasionally detected.
Wellstestinghighinbacteriaornitrate-nitrogenmayindicatetoo
muchfertilizerisbeingusedorasepticsystemistooclosetothe
well. High levels of nitrate should be monitored, especially if
pregnantwomenorinfants are usingthesupply.
Water testing services are available at the Barnstable County
DepartmentofHealthandtheEnvironmentWaterLab,locatedin
the Superior Court Buildingon Route 6A in Barnstable Village.
Thecharge fora routineanalysisis$25persampleand $75 fora
volatile organic compound analysis. Sterilized containers must
be used and areavailable atthe lab and thehealth department.
Foradditionalinformation on watersupplies:
•HarwichWater Department [phone]
•HarwichHealthDepartment [phone]
•CapeCod Commission [phone]
•CapeCod Cooperative Extension (508)362-25n
•Barnstable CountyDept. of
Health and the Environment [phone]
•Dept. ofEnvironmental Protection,
Southeast RegionalOffice [phone]
CapeCod Commission
E-mail: [email protected]
WorldWideWeb: http://www.capecodcommission.org