N.M. Admin. Code § 20.7.3.812

Current through Register Vol. 35, No. 17, September 10, 2024

Section 20.7.3.812 - SAND-LINED TRENCHES AND BOTTOMLESS SAND FILTERS

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.

N.M. Admin. Code § 20.7.3.812

20.7.3.812 NMAC - N, 9/1/13