Section 327IAC8-4.1-5. Criteria for selecting the delineation method for determining the wellhead protection area

   (a) During Phase I of the WHPP, the CPWSS must delineate the WHPA using one (1) of the five (5) accepted methods of delineation.

  (b) Any CPWSS may use the following methods:

(1) The analytical method.

(2) The numerical flow/solute transport model methods.

(3) The semianalytical method.

  (c) A CPWSS may use the hydrogeologic mapping method as set out in the "Guidelines for Delineation of Wellhead Protection Areas"* as the sole method of delineation with prior approval from the department.

  (d) A CPWSS may use the fixed radius method after receiving prior approval from the department. Approval to use the fixed radius method is based on either of the following criteria:

(1) A CPWSS does not qualify as a significant water withdrawal facility (in accordance with IC 14-25-7).

(2) A CPWSS qualifies as a significant water withdrawal facility, in accordance with IC 14-25-7, and the average daily withdrawal is less than one hundred thousand (100,000) gallons per day demonstrated by:

(A) submittal of annual total pumping data for the previous five (5) years of operation to the department; and

(B) statistical determination by the department of an upper confidence interval of one hundred thousand (100,000) gallons per day or less by the following formula:

= t_{(0.95, n-1)}(S/n^1/2)

	=	Mean of pumping data
S	=	Standard deviation of pumping data
t(0.95,n-1)	=	t statistic at 95%, n degrees of freedom
n	=	Number of observations

  (e) Upon selecting and carrying out a delineation method, a CPWSS must submit justifying data in accordance with section 8 of this rule.

  (f) All delineation methods available to CPWSSs for defining the WHPA are outlined within "Guidelines for Delineation of Wellhead Protection Areas"*.

  (g) Site characterization and WHPA delineation, using either the modeling methods, described in subsection (b), or hydrogeological mapping methods described in subsection (c), must be performed by a qualified ground water scientist.

  *"Guidelines for Delineation of Wellhead Protection Areas", United States Environmental Protection Agency, Office of Ground Water Protection, Washington, D.C. 20460, June 1987, EPA Publication No. 440/5-93-001. Copies of "Guidelines for Delineation of Wellhead Protection Areas" are available at the Indiana Department of Environmental Management, Office of Water Quality, Drinking Water Branch, Ground Water Section, 100 North Senate Avenue, Room N1255, Indianapolis, Indiana 46204. (Water Pollution Control Division; 327 IAC 8-4.1-5; filed Feb 28, 1997, 4:18 p.m.: 20 IR 1724; errata filed Jun 25, 1997, 3:55 p.m.: 20 IR 3016; readopted filed Jan 10, 2001, 3:23 p.m.: 24 IR 1518; errata filed Feb 6, 2006, 11:15 a.m.: 29 IR 1937; readopted filed Nov 21, 2007, 1:16 p.m.: 20071219-IR-327070553BFA; readopted filed Jul 29, 2013, 9:21 a.m.: 20130828-IR-327130176BFA)