R 325.10813 Study of hydrogeological conditions by type I and type IIa public water supplies.

Rule 813. (1) A type I or type IIa public water supply shall prepare a study of hydrogeological conditions for determination of an isolation area and the acceptability of a test well location. The study shall be provided to the department and approval obtained. (2) Previous studies of hydrogeological conditions that meet the criteria and intent of this rule may be considered by the department in determining the scope of or need for a study. (3) A study of hydrogeological conditions shall mean investigations and a compilation and evaluation of data necessary to determine the isolation area, the acceptability of a test well location and construction, and the availability of water at that location. The study of hydrogeological conditions may include the following: (a) The type of public water supply. (b) The well capacity required of the public water supply. (c) The test well depth and construction features. (d) Identification of geological formations, including the thickness and characteristics of the aquifer, the number and thicknesses of protective layers, and if deemed necessary by the department, the areal extent of the protective formations. (e) Location of the test well relative to sources of contamination. (f) Susceptibility of the test well location to flooding. (g) Depth to the water table from the established ground surface. (h) Proximity of the well to surface water. (i) An aquifer test of the well in accordance with R 325.10830. (j) Water quality analyses. (k) Identification of the contributing area to a well based on ground water flow simulations using a computer model as approved by the department. (l) The location of the test well as a latitude and longitude expressed in degrees-minutes- seconds or degrees-decimal degrees to 5 significant digits. (4) The scope of the hydrogeological study may vary depending on the capacity required of the public water supply in relation to the aquifer capacity, the need for a modification of a standard isolation area, or other factors; and may include additional determinations required by the department, such as the general aquifer characteristics and interference relative to other wells and surface waters in proximity to the well site. (5) Where an adverse resource impact, as defined in section 32701 of 1994 PA 451, MCL 324.32701 is likely to occur, the department may require the public water supply to provide for the collection of stream or river flow measurements on stream segments likely impacted by the operation of a well or wells by the public water supply. Flow measurements shall be required on not more than 2 potentially impacted stream segments selected by the department. When required by the department, the public water supply shall provide not fewer than 5 miscellaneous measurements of flow from each stream taken at a frequency of once a month from June to October, and not more than continuous flow monitoring in each stream for 6 months before to 1 year after the well or wells are put in service.