1. (1) The hydrogeologic properties of the proposed disposal area shall be identified and recorded on the evaluation form with respect to the following:

   1. (a) estimated direction of ground-water flow;
   2. (b) high ground-water elevation;
   3. (c) estimated depth to bedrock if a factor in design of proposed system, or actual depth if encountered during deep observation hole tests;
   4. (d) depth of unsaturated zone, including any perched water tables;
   5. (e) drainage classification of dominant soil type as defined by NRCS;
   6. (f) lateral distance to surface water and wetland delineation;

   7. (g) location of every water supply, public and private,

      1. 1. within 400 feet of the proposed system location in the case of surface water supplies and gravel packed public water supply wells,
      2. 2. within 250 feet of the proposed system location in the case of tubular public water supply wells, and
      3. 3. within 150 feet of the proposed system location in the case of private water supply wells;
   8. (h) approximate safe yield or design capacity of every public water supply, if information is available; and
   9. (i) identification of proposed disposal area in relation to the location of nitrogen sensitive areas designated pursuant to 310 CMR 15.214.
2. (2) When observation wells are appropriate or necessary to determine the hydrogeologic properties of a site or region, such as direction of ground-water flow, perched ground-water tables and seasonal ground-water elevation fluctuations, the general guide for the proper use and installation of ground-water observation wells provided in Department guidance shall be followed.

SUBPART C: DESIGN, CONSTRUCTION, REPAIR, AND REPLACEMENT OF

ON-SITE SEWAGE DISPOSAL SYSTEMS