Minor subdivision and minor land development project approval and major subdivision and major land development project approval -- well field test
A. If the proposed development anticipates maximum groundwater use of 4,600 gallons a day or greater, if wells will be closer than 200 feet to each other, if industrial development is proposed, or if the Planning Board finds, based on the peer review of the preliminary hydrogeologic evaluation, that the proposed development could have a significant impact on the quality or quantity of the groundwater at the property or adjacent properties, the applicant shall carry out a well field test. The purpose of the well field test is to conduct pumping tests to determine available yield and groundwater flow direction, and to demonstrate that wells on the property will produce potable water. Pumping test data must be plotted, interpreted, and analyzed. The method of analysis and the resulting aquifer properties, including well yield, specific capacity, transmissivity, and storage, must be described. The analysis shall be submitted with the Preliminary Plan application.
(Ord. dated 7-18-23; Ord. dated 5-21-24)
B. The following requirements apply to well field tests:
1. Test wells shall be drilled bedrock wells unless overburden wells are planned for the proposed development.
2. For residential development, one well is required for 2 to 4 units, two wells are required for five to ten units, three wells are required for eleven to twenty-four units, four wells are required for twenty-five to fifty units, five wells are required for fifty-one to seventy-five units, and six wells are required for seventy-six to one hundred units.
(Ord. dated 5-21-24)
3. For residential development, the test well should be located throughout the property in a way that will accurately reflect the hydrogeologic conditions throughout the site. For commercial or industrial development, the test well shall be located at the proposed location of the water supply well. Wells must be located so that well water is discharged a sufficient distance away from other test wells to prevent inaccurate readings.
4. Construction of test wells must comply with applicable State regulations and must be supervised by a qualified engineer, geologist or hydrologist who will record detailed site geology information during installation.
5. Pumping tests should be carried out at all test wells. Before pumping tests take place, wells should be free of sand and mud. Discharge water should be checked periodically for sediment during the test. Excessive sediment indicates that the well needs additional development.
6. Initial step drawdown pumping tests appropriate for the proposed use should be performed in all test wells to estimate well yields and to determine the optimum rate for a constant rate pumping test. The step drawdown pumping tests should include a minimum of four pumping intervals consisting of a minimum period of thirty minutes each. The constant rate pumping tests should begin with a static water level and should be performed at a fixed pumping rate (plus or minus 5%) for a minimum of eight hours for residential development, and forty-eight hours for commercial or industrial development.
7. Before a constant rate pumping test, test wells should be sufficiently recovered. When a constant rate pumping test is taking place on one well, other test wells should be used as observation wells, with drawdown and recovery times recorded. A pumping test should include regular water level measurements during and after pumping until 95% recovery occurs, or until sufficient data have been collected to establish a recovery curve. Water levels should be continuously monitored at an appropriate frequency in pumping wells and observation wells.
8. Water level should be measured in feet and hundredths of a foot. The flow rate during the pump test should be measured using a flow meter and flow totalizer. Flow rate readings should be documented every hour and confirmed with a 5-gallon bucket and stopwatch.
9. A water sample should be collected at the end of the pump test. Water quality testing must comply with approved U.S. environmental protection agency methods. Samples must be analyzed by a State certified laboratory for the substances listed below, and for any other substances the planning board has reason to believe might be present.
a. Arsenic
b. Alkalinity
c. Hardness
d. pH
e. Chloride
f. Cadmium
g. Iron
h. Sodium
i. Total dissolved solids
j. Conductivity
k. Lead
l. Total coliform bacteria
m. Copper
n. Manganese
o. E. coli bacteria
p. Fluoride
q. Sulfate
r. Zinc
s. Mercury
t. Nitrate/nitrite
u. Volatile organic compounds (VOCs)
v. Methyl tert-butyl ether (MTBE)
w. Pesticides
10. If a well is drilled into bedrock, gross alpha screen and radon testing shall be performed. If the gross alpha screen detects radiation of 15 or more picocuries per liter of air (pCi/L), the water must be analyzed for radium and uranium concentrations.
11. After field testing is complete, test wells that will not be used for water supply or long-term monitoring must be decommissioned.
C. The planning board shall have the authority to impose conditions on approval that are intended to maintain groundwater quality and to minimize groundwater withdrawal. The planning board shall make findings of fact to support the imposition of any condition.
(Ord. dated 7-18-23; Ord. dated 5-21-24)
REFERENCES
Title 46, chapter 13.1 of the general laws; R.I. Gen. Laws § 45-24-30(3)(i), § 45-24-30(4); § 45-24-33(a)(7), (20).
250-RICR-150-05-3 - DEM Groundwater Quality Rules.
250-RICR-150-10-6 - DEM Rules Establishing Minimum Standards Relating to Location, Design, Construction and Maintenance of Onsite Wastewater Treatment Systems.
250-RICR-140-25-1 - DEM Rules and Regulations for Underground Storage Facilities Used for Regulated Substances and Hazardous Materials.
250-RICR-140-10-1 - DEM Rules and Regulations for Hazardous Waste Management.