(a) Projections of groundwater quality shall be based on the assumption of drought conditions (assuming 60% of annual average precipitation). See
§ 120-910C(3)(c)[3] for hydrogeologic assessment submission requirements.
(b) No subdivision shall increase any contaminant concentration in the groundwater at any subdivision water supply well or any project boundary to more than the primary drinking water standards. No subdivision shall increase any contaminant concentration in the groundwater at said locations to more than the secondary drinking water standards. A hydrogeological evaluation shall demonstrate that the groundwater concentrations of nitrate as nitrogen meet the maximum contaminant level standard of 10 mg/L of the EPA's National Primary Drinking Water Regulations at the project boundaries. Where past land activities, such as agriculture, indicate the potential for high background levels of nitrate nitrogen or other groundwater contaminants, the Planning Board may require testing to determine background levels and may place limitations on total groundwater discharges to ensure safe drinking water supplies for existing and/or proposed households.
(c) If groundwater is to be used for potable purposes and contains contaminants in excess of the primary standards, and the subdivision is to be served by on-site groundwater supplies, the applicant shall demonstrate how water quality will be improved or treated.
(d) If groundwater contains contaminants in excess of the secondary standards, the subdivision shall not cause the concentration of the parameters in question to exceed 150% of the ambient concentration.
(e) Subsurface wastewater disposal systems and drinking water wells shall be constructed as shown on the map submitted with the assessment. If construction standards for drinking water wells or other measures to reduce groundwater contamination and protect drinking water supplies are recommended in the assessment, such as required well-exclusion zones, those standards shall be included as a note on the final plan, and as restrictions in the deeds to the affected lots.
(f) Whenever the Board determines that there is a potential that some lots in the proposed subdivision may have difficulty obtaining a well with adequate quantity and quality for potable water, the developer shall be required to drill wells and verify the water supply before the lot is sold.
