- A. Effluent applied to a sand-lined trench shall not exceed primary treatment standards.
- B. The required absorption area shall be calculated based on a maximum loading rate of 1.00 gallon per day per square foot of sand surface. No sidewall credit is allowed.
- C. The distribution system shall conform to the requirements of 20.7.3.807 NMAC, Low Pressure Disposal Systems.
- D. A minimum of 24 inches of sand, meeting the latest version of ASTM specifications, shall be installed beneath the distribution system.
- E. Trench width shall be a minimum of 12 inches and a maximum of 36 inches.
- F. The effluent dosing rate shall be at least four doses per day and not more than 24 doses per day.
G. A sand-lined trench may be used to reduce setbacks and clearances as follows:
(1) one foot to a limiting layer;
(2) 50 feet to waters of the state; or
(3) 50 feet to an irrigation well located on the subject property.
- H. A bottomless sand filter is a special case sand-lined trench consisting of a bottomless containment structure located partially above or at grade of the existing ground level. A bottomless sand filter must be located parallel to the contours on a sloping site and be as long and narrow as possible to limit the linear loading rate on the disposal area.
- I. A maintenance contract shall be required. Maintenance is to include pump inspection and cleaning, float operation (if applicable), lateral flushing annually at a minimum and septic tank and pump tank pumping as needed.
[20.7.3.812 NMAC - N, 9/1/13]