1. (a) Each lot created after September 1, 1989 shall contain not less than the area required for the greater of:

   1. (1) A wastewater load of 600 GPD; or
   2. (2) The wastewater load calculated for the proposed use based on the unit design flows specified in Env-Wq 1008.04(f), Table 1008-1.

2. (b) Lot size shall be calculated on the basis of the site loading for each soil type on the lot, subject to the following:

   1. (1) In all cases, the lot shall contain a minimum of 20,000 contiguous square feet (SF) of soil suitable for a receiving layer;
   2. (2) At least 4,000 SF of the contiguous area, excluding the footprint of the building to be served by the ISDS, shall meet all applicable requirements for the placement of an ISDS; and
   3. (3) For lots on which the primary use is not a single-family house, the area required by (a)(2) shall contain one or more areas on which one or more EDAs designed to accept the proposed flow can be installed.

3. (c) To show the suitable contiguous area, the applicant shall:

   1. (1) Show the area on the plan with the test pit;
   2. (2) Submit an acceptable ISDS design meeting all applicable requirements of Env-Wq 1003 and having the minimum design flow specified in (a), above; or
   3. (3) Submit a copy of a department-issued construction approval with approved plans and specifications, including test pit data based on Munsell Soil Color Charts (2009), available as noted in Appendix B, for an ISDS on the lot having the minimum design flow specified in (a), above.

4. (d) When test pits indicate conditions other than those derived based on USDA-NRCS soil maps, the following shall apply:

   1. (1) If reported soil conditions are better than indicated by the USDA-NRCS soil maps and the submitted test pit data is not consistent with the department’s on-site inspection, the department shall request new test pits for inspection by department staff to determine the soil’s capability for effluent disposal; and
   2. (2) If reported soil conditions are worse than indicated by the USDA-NRCS soil maps, the reported site conditions shall be used as a basis for calculating minimum lot size.
5. (e) Land created by filling with soil from off-site, as classified by the USDA-NRCS, shall be assessed on its own soil characteristics.

6. (f) The following areas shall not be included as available land when calculating minimum lot size, even though a lot’s boundaries might include these areas:

   1. (1) Surface waters, including lakes, ponds, rivers, and streams;
   2. (2) Very poorly drained soils;
   3. (3) All land within the protective well radius of an on-lot well;
   4. (4) Any legally-established or proposed easement or right-of-way, such as for utility lines or for passage, if the easement or right-of-way grants an exclusive use or explicitly excludes the area from using it for the disposal or treatment of sewage;
   5. (5) Areas of ledge outcrop; and
   6. (6) Any area having a slope in excess of 35%.
7. (g) The slope of a lot shall be determined by either finding the average slope across the lot, measured perpendicular to the contours, or by depicting areas within the boundaries of a lot that have different slopes.
8. (h) For lots with peaks, gullies, or ridges, a composite average slope shall be used.

Source. (See Revision Notes #1 and #2 at chapter heading for Env-Wq 1000) #11184, eff 10-1-16; amd by #12716, eff 1-24-19; ss by #14486, eff 2-1-26, EXPIRES: 2-1-36