Conn. Agencies Regs. § 22a-354b-1 - Regulations for mapping wells in stratified drift aquifers to level A standards
Current through March 4, 2022
"Aquifer test" means a yield test conducted for the purposes of evaluating the capacity of a well or well field for withdrawing water from an aquifer, of analyzing the hydraulic properties of the aquifer, of evaluating the effects of induced infiltration on surface water bodies, and/or of identifying the effects of other boundaries on the pumping well(s).
"Area of influence" means the land area that directly overlies and has the same horizontal extent as the part of the water table or other potentiometric surface that is perceptibly lowered by the withdrawal of water. The area of influence delineated by the use of modeling shall be that area of land in which the water table or potentiometric surface is lowered by at least 0.5 feet.
"ASCII" means American Standard Code for Information Interchange.
"Calibration" means the adjustment of model input data for the purpose of matching model-generated output with field-measured values.
"Commissioner" means the Commissioner of Environmental Protection or his designated agent.
"Conceptual model" means a qualitative description of the physical characteristics and operating processes of an aquifer system.
"Critical drought event for stream flow" means the lowest average stream flow over a continuous period of seven days with a calculated return frequency or recurrence interval of once in every ten years.
"Hydraulic boundaries" means boundaries as described in the U.S. Geological Survey publication entitled, Techniques of Water Resources Investigations of the United States Geological Survey, Book 3, Chapter B5, "Definition of Boundary and Initial Conditions in the Analysis of Saturated Ground-Water Flow Systems - An Introduction," O. Lehn Franke, Thomas E. Reilly, and Gordon D. Bennett, 1987.
"In use," when referring to existing well fields in use, means well fields in which any constituent well is identified, in the water supply plan which is current as of the date that level A maps are required to be complete under section 22a-354c and 22a-354d of the general statutes, as an active source of supply and which is not identified as solely an emergency source of supply.
"Indirect recharge area" means an area from which water by overland flow or ground-water discharge is contributed to a surface watercourse which flows into the area of contribution.
"Initial setback" means a distance from a pumping center that would represent the radius of an area approximately equal to the area of influence, as determined from Level B mapping.
"Level B mapping" means a methodology to map the locations of existing and potential well fields, as required pursuant to Section 22a-354b of the general statutes.
"Model" means a representation of a natural system consisting of a mathematical representation of two- or three-dimensional flow in an aquifer based on differential equations known to govern ground-water flow.
"Sensitivity analysis" means an analysis which determines the degree of influence that various input parameters have on model results by varying individual input parameter values during a series of simulations.
"Simulation" means the use of an operating model of a system or process.
"Sink" means a process whereby, or a feature from which, water is extracted from the ground-water flow system.
"Stratified drift aquifer" means a predominantly sorted sediment laid down by or in meltwater from glaciers and includes sand, gravel, silt and clay arranged in layers.
"Source" means a process whereby, or a feature from which, water is added to the ground-water flow system.
"Steady state flow" means a condition in which the amount of water flowing into a defined volume of the aquifer is equal to the amount flowing out of that volume. Under steady state flow conditions the head distribution in an aquifer is constant over time.
"Transient flow" means a condition in which the amount of water flowing into a defined volume of the aquifer is equal to the amount flowing out of that volume plus or minus some amount of water held in the volume as storage. Under transient flow conditions the head distribution in an aquifer varies as a function of time.
"Verification" means demonstration of a calibrated model's ability to simulate an historic hydrologic event for which field data are available.
"Water budget mass balance" means an accounting of volumes and rates of water gains and losses from ground water, produced by a computer model simulation.
"Water supply plan" means a plan prepared by a water company serving more than 1000 persons and approved by the Department of Health Services pursuant to section 25-32d of the general statutes.
Each water company required by Sections 22a-354c and 22a-354z of the general statutes, to perform Level A mapping for existing well fields in use and potential well fields shall submit to the Commissioner for his review and written approval two copies of a plan for data collection and analyses which meets the requirements of subsections (d) and (e) of this section, and includes the information specified in subdivisions (1) through (5) of this subsection. Maps and reports prepared to fulfill Level B mapping, diversion applications pursuant to section 22a-369 of the general statutes, and ground water safe yield calculations provided in a water supply plan may be included in the plan to provide data to satisfy some of the requirements of this subsection. The plan shall include the following:
All hydrogeologic data used in determining the area of contribution and the recharge area pursuant to this section shall be collected in accordance with the provisions of this subsection. Any data type not described in this subsection shall be collected, processed and interpreted in an accepted scientific manner, with references to methods used specified in the plan for data collection and analysis required by subsection (b) and final reports required by subsection (g).
The number and locations of test borings shall be adequate to fully define the aquifer stratigraphy, given the approximate size of the area of contribution and the complexity of the aquifer material. The test borings shall be conducted as follows:
Observation wells and piezometers shall be adequate in number, of proper construction, and in proper locations to allow determination of aquifer parameters, the response to the stress created by the aquifer tests, and the locations and effects of hydraulic boundaries. The number and location of observation wells and piezometers shall be determined by the approximate size of the area of contribution, the complexity of the aquifer system and the number and location of the well(s) to be pump tested.
Stream flow or water stage measurements shall be made, where such measurements will provide accurate and meaningful data, to establish the volume of water flowing in streams or other surface watercourses before, during and after an aquifer test period to determine the effects of an aquifer test on the stage or flow of surface water.
Aquifer tests shall be performed to determine aquifer properties such as transmissivity and storage coefficient, to evaluate hydraulic boundary conditions, to provide data for model calibration and verification and to quantify induced infiltration from surface water bodies. The aquifer test to quantify induced infiltration may be combined with the aquifer test to quantify aquifer properties and evaluate boundary conditions if the conditions of subsections (d) (4) (A) and (d) (4) (B) can be met:
Numerical modeling of ground-water flow shall consist of separate but related operations, as set forth in subparagraphs (1) to (3), inclusive, of this subsection. The model shall, at a minimum, cover the stratified drift areas.
Each water company shall submit two copies of the maps, reports and computer data listed in subdivisions (g)(1) through (g)(6) of this subsection to the Commissioner for review and written approval.
Existing or potential well fields for which the Commissioner has allowed analytical modeling under subparagraph (b) (4) (A) (iv) shall be mapped at Level A in accordance with subdivisions (1) through (5) of this subsection. Unless otherwise specified, below, data shall be collected in accordance with subsection (d) of this section.
If, at any time after written approval of a Level A map under section 22a-354d of the general statutes, a water company becomes aware that hydrogeologic conditions have changed such that a change in the boundaries of an area of contribution or recharge areas on the Level A map can reasonably be expected, or that any information submitted to the Commissioner under this section was not compiled in accordance with this section, was erroneous or any relevant information was omitted, the water company shall, within thirty days of becoming so aware, submit notice of such change, error or omission to the Commissioner. The Commissioner may require a water company to submit a revised Level A map whenever hydrogeologic conditions have changed such that a change in the boundaries of an area of contribution or recharge areas on the Level A map can reasonably be expected, or whenever he finds that any information submitted under this section was not compiled in accordance with this section, was erroneous, was unreliable, any relevant information was omitted, or if, in a case where analytical modeling has been allowed in lieu of numerical modeling under subparagraph (b) (4) (A) (iv) (dd), land use or land use controls change and contamination threats increase. Such mapping shall be performed in accordance with this section, at a time and on a schedule determined by the Commissioner.
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