N.M. Admin. Code § 20.7.3.302
Current through Register Vol. 35, No. 21, November 5, 2024
Section 20.7.3.302 - STANDARDS; SETBACK REQUIREMENTSA. On-site liquid waste systems shall be located to meet setback distances, in feet, specified in the following Table 302.1. Setback distances apply to any part of the on-site liquid waste system. Table 302.1: Minimum setback and clearance requirements
| From: To: | Building Sewer | Treatment Unit* | Disposal Field | Seepage Pit |
| Property lines | clear | 5 ft. | 5 ft. | 8 ft. |
| Building or structure | 2 ft. | 5 ft. | 8 ft. | 8 ft. |
| Distribution box | -- | -- | 5 ft. | 5 ft. |
| Disposal field | -- | 10 ft.***** | 4 ft**** | 10 ft. |
| Seepage pit | -- | 10 ft. | 10 ft. | 12 ft. |
| Drinking water line******: |
| - private | 1 ft. | 10 ft. | 10 ft. | 10 ft. |
| - public | 10 ft. | 10 ft. | 10 ft. | 10 ft. |
| Drinking water source/well: |
| - private | 50 ft. | 50 ft. | 100 ft. | 100 ft. |
| - public | 50 ft. | 100 ft. | 200 ft. | 200 ft. |
| Irrigation well | 50 ft. | 50 ft. | 100 ft. | 100 ft. |
| Lined canals | -- | 10 ft.** | 10 ft.** | 10 ft.** |
| Unlined canals, drainage ditches | -- | 15 ft.** | 25 ft.** | 25 ft.** |
| Arroyos | -- | 15 ft.** | 25 ft.** | 25 ft.** |
| Other watercourses, |
| Waters of the state | -- | 50 ft. | 100 ft. | 100 ft. |
| Retention/detention area or flood irrigation areas | -- | 15 ft. | 15 ft. | 15 ft. |
| Seasonal high water table, bedrock and other impervious layers*** | -- | -- | 4 ft. to bottom of system | 4 ft. to bottom of system |
(1) * Applies to privy pits, enclosed systems, other liquid waste treatment units.(2) ** Plus depth of channel.(3) *** Unlined privy pits shall provide clearance of at least four feet.(4) **** Plus two feet for each additional foot of depth below the invert of the distribution pipe.(5) ***** May be five feet when Schedule 40 PVC/DWV pipe is used.(6) ******Or applicable plumbing code.B. Setback distances to watercourses, canals and arroyos shall be measured from the edge of the defined bank to the on-site liquid waste system component. Setback distances to artificially controlled lakes or reservoirs shall be measured from the closest projected shoreline at the maximum controlled water level.C. Multiple liquid waste systems, each with an actual design flow of 5,000 gallons per day (gpd) or less, may be permitted by the department even if they are located on a single lot provided that the disposal systems are set back from each other by a distance equal to the sum of two radii of adjacent circular areas, each circular area representing certain boundaries of a disposal system. The center of each circle is located at a point nearest to the outer boundary of each adjacent liquid waste disposal system. The radius for each circle may be calculated utilizing Table 302.2 below based on the number of bedrooms, or by using the following formula: r = [Square Root](A/[Pi]) or r2 = A/[Pi], where: (1) "r" means radius of the circular area measured in feet;(2) "[Square Root]" means square root;(3) "A" means the area of a circle in square feet, calculated as follows: (a) A = (design flow, gpd) x (1 acre/500 gpd) x (43,560 square feet/acre); or(b) A = (design flow, gpd) x 87.12; andD. Table 302.2 below provides examples of radii for design flows based on number of bedrooms only. Radii for other design flows shall be calculated with the formula above. Separation distances to facilities permitted by other entities, such as the ground water quality bureau, may be considered on a case by case basis. Table 302.2: Radii for calculating minimum distance between systems on a large parcel
| No. of bedrooms | Actual flow, gpd | Minimum acreage | Radius of A, feet |
| 1 | 150 | 0.75 | 102.0 |
| 2 | 300 | 0.75 | 102.0 |
| 3 | 375 | 0.75 | 102.0 |
| 4 | 440 | 0.88 | 110.5 |
| 5 | 500 | 1.0 | 117.8 |
| 6 | 550 | 1.1 | 123.5 |
E. In order to meet the criteria of this section, the disposal system may be moved to meet the minimum separation distance. This may require the use of an effluent pump system. Alternatively, if the minimum separation distance cannot be achieved, tertiary treatment may be installed. Other methods of providing equal protection will be considered on a case by case basis by the department.F. Lots with existing liquid waste systems totaling less than 5,000 gallons per day may be permitted to add additional liquid waste systems provided the individual systems do not exceed 5,000 gallons per day, meet the setback requirements to the existing systems as allowed above and meet lot size requirements in Subsection C of 20.7.3.301 NMAC.G. If the department discovers that a private drinking water well has been drilled at a location that is not set back from an existing liquid waste system by the distance required in Table 302.1, the department shall: (1) send a certified letter to the owners of the water well and liquid waste system that identifies the subject water well and liquid waste system, and describes the potential hazards created by insufficient setback;(2) provide the office of the state engineer with a copy of the letter; and(3) not administer the water well setback requirements in Table 302.1 pertaining to the subject well provided that the liquid waste system remains in compliance with 20.7.3 NMAC, and is not modified.N.M. Admin. Code § 20.7.3.302
20.7.3.302 NMAC - Rp, 20.7.3.302 NMAC, 9/1/13; A, 9/1/13Amended, New Mexico Register, Volume XXV, Issue 15, August 15, 2014, eff. 9/15/2014