[HISTORY: Section 3 of the Plainville Board of Health Regulations.
Amendments noted where applicable.]
A.
These rules and regulations have been adopted to protect the water
supplies of the residents of Plainville from excessive contamination
of nitrate and other harmful chemicals resulting from the subsurface
discharge of wastewater effluent. Nitrate contamination of drinking
water is a serious public health problem. Nitrate also may serve as
an indicator of other groundwater degradation associated with the
use of household and industrial chemicals, pesticides, solvents, and
other toxic substances. Therefore, the presence of those other substances
may be presumed to be present also, when more than natural background
levels of nitrate occur. Subsurface wastewater disposal, without nitrogen
removal, is a major source of nitrate-nitrogen loading in the groundwater
and surface waters.
B.
These rules and regulations shall also protect surface water and
groundwater from excessive nitrate-nitrogen and other nutrient loading
and will retard the process of eutrophication of the lakes and ponds.
C.
By requiring sufficient dilution of nitrates as well as these other
by-products of human activity, they may be decreased to a level which
does not constitute a threat to the public health. Adequate land area
surrounding a subsurface sewage disposal system will result in the
dilution of the subsurface sewage discharge to levels of contaminants
that will not constitute a threat to public or environmental health.
D.
The Town of Plainville derives its water supply from groundwater.
The groundwater supplies both the public water system and individual
on-site wells. The groundwater of the Town of Plainville, and the
surface waters which contribute to the groundwater, constitute its
water supply. Therefore, this regulation shall apply to any subsurface
wastewater disposal system located within the zone of contribution
of a public water supply well, located in an area of private well
supplies, located within the watershed of Turnpike Lake, Mirimichi
Lake, or any other pond in the Town of Plainville, or within the watershed
of any stream which drains into said lakes and ponds.
E.
This regulation shall not apply for the repair of existing septic
systems where there is no increase in wastewater flow or there is
no change of use. It shall not apply where there is connection to
Town sewer.
A.
The applicant for construction of any subsurface wastewater system
in the Town, except for repairs of existing systems which have failed
and are not being enlarged to provide for additional building construction
or use, shall submit a groundwater impact report (GIR) to the Board
of Health. In the case of a subdivision, the GIR shall be submitted
at the time of submittal of the preliminary plan. In case of lots
not requiring approval as a subdivision, the GIR shall be submitted
at the time of application for a disposal works construction permit.
A.
The GIR shall be based on the following methodology for determination
of nitrate loading which is based on procedures that have been accepted
by and have been adopted and used by governmental planning agencies,
enforcement agencies, and the U.S. Geological Survey. The GIR shall
determine whether or not the proposed project will cause unacceptable
groundwater quality at the project boundary limits for the proposed
use, based on the expected nitrate-nitrogen loading. The calculations
shall follow the guidelines contained herein, using data which is
appropriate for the Town of Plainville.
B.
The maximum allowable calculated concentration of nitrate-nitrogen
within each project boundary shall be five milligrams per liter in
Zone II of the public water supply and areas of private on-site well
water supplies. It shall be 7 1/2 milligrams per liter in all
other areas within the Town.
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CRITERIA AND FORMULA ASSUMPTIONS
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NITRATE NITROGEN MAXIMUM ALLOWABLE CONCENTRATION (NMAX)
AT PROJECT BOUNDARY:
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At project boundary:
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5 milligrams per liter in Zone II for the Public water supply.
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5 milligrams per liter for areas of private wells.
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7.5 milligrams per liter for all other areas.
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In the case of multistructure or multilot projects in Zone II
in areas of private wells, the maximum allowable concentration shall
be no greater than 7.5 milligrams per liter at any individual lot
line, but shall be no greater than (NMAX) at the project boundary.
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In the case of multistructure or multilot projects in all other
areas, the maximum allowable concentration shall be no greater than
10 milligrams per liter at any individual lot line, but shall be no
greater than (NMAX) at the project boundary.
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ASSUME COMPLETE MIXING AND STEADY STATE (EQUILIBRIUM) CONDITIONS.
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CONTAMINANT ATTENUATION IS CAUSED BY DILUTION ONLY.
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EVAPOTRANSPIRATION FROM SEPTIC SYSTEMS IS 10%.
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PRECIPITATION RECHARGE TO GROUNDWATER:
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Nitrate-Nitrogen Concentration — 0.05 milligrams per liter
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Quantity:
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Inches per Year
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Soil Percolation Rate Minutes per Inch
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|---|---|---|---|
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19
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Less than 2
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17
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2 to 4.9
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15
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5 to 9.9
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13
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10 to 14.9
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11
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15 to 19.9
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9
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20 +
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0
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Impervious areas with no recharge
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Wetlands shall be considered having a percolation rate greater
than 20 minutes per inch for this calculation purpose.
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WATER SUPPLY:
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Town water: Nitrate-Nitrogen Concentration — 2.5 milligrams
per liter
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Private Water: 5 milligrams per liter
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HOME SEPTIC SYSTEM:
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Nitrate-Nitrogen Quantity — 5 pounds per person per year
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Quantity of sewage — 55 gallons per person per day
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Persons per household — 3
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LAWN FERTILIZER
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1.2 pounds of nitrogen per 1,000 square feet of lawn per year.
This is an estimated mean considering homeowner application, professional
application, and lawns that are not fertilized.
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Average lawn size: 10% of lot area unless specifically known.
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OTHER:
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Criteria for uses or other criteria not included herein shall
be evaluated on a case-by-case basis according to criteria that is
acceptable to the Board of Health. Applicants should contact the Board
of Health office prior to conducting such calculations for the purpose
of establishing such other criteria.
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MIXTURE FORMULA FOR NITROGEN LOADING
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Wc =
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(Rc times Rv) + (Nt) + Lt
Rv + (0.9 times Sv) + Vv
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Where:
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Wc
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=
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Nitrate-nitrogen concentration in the groundwater
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Rc
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=
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Nitrate-nitrogen concentration in the rain
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Sc
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=
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Nitrate-nitrogen concentration in septic effluent
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Rv
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=
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Volume of recharge from rainfall
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Sv
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=
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Volume of septic system effluent
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Lt
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=
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Amount of nitrate-nitrogen from lawn fertilizer and other sources
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Vv
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=
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Volume of any other recharge waters
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Nt
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=
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Amount of nitrate-nitrogen in septic system effluent
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(5 pounds per person per year for a dwelling. Sc times Sv for
other types of facilities.)
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