New Mexico Administrative Code
Title 20 - ENVIRONMENTAL PROTECTION
Chapter 7 - WASTEWATER AND WATER SUPPLY FACILITIES
Part 3 - LIQUID WASTE DISPOSAL AND TREATMENT
Section 20.7.3.303 - STANDARDS; CLEARANCE REQUIREMENTS

A. Seasonal high groundwater levels and seasonal high water flows shall be determined by the department either by direct observation, by the presence of mottling in the soil profile, by reliance upon the findings of a qualified professional or upon published scientific material, well records or other sources acceptable to the department. The department may adjust the measured water table to compensate for factors such as season, drought, irrigation or flooding. Compliance with seasonal high groundwater table and seasonal high water flow clearances in this section shall be based on the best-documented evidence available to the department at the time of installation or modification.

B. No conventional on-site liquid waste system shall discharge liquid waste into the soil where the vertical clearance from the bottom of the absorption area to seasonal high groundwater table, impervious formation or other limiting layer is less than four feet of suitable soil. A reduction in this clearance may be allowed with appropriate advanced treatment or alternative disposal.

C. Unlined privy pits shall provide a clearance of no less than four feet of suitable soil from the bottom of the excavation to the seasonal high groundwater table, the seasonal high water flow, impervious formation or other limiting layer.