Taos Real Estate

NEW MEXICO ENVIRONMENT DEPARTMENT

LIQUID WASTE SUMMARY

(Flows under 2,000 gallons per day)

Permits:  Any person in the State of New Mexico who does not have access to a community sewer system must obtain a Liquid Waste Permit issued by the New Mexico Environment Department before building or transporting a home onto a property.   A permit is also required for any modification to the system or property i.e. change the disposal method, change the design flow, replace part or all of the system, or change the lot size of the property.   A permit can be obtained by completing the application form and providing the Department with the following items: floor plans, recorded warranty deed, Uniform Property Code, and a soil analysis.  A test hole may also be required if you are building in an area where it is suspected that a high water table or bedrock problems exist.   Permits may be cancelled by the Department if the system is not completed within one year or it is found that information provided in the application is false or inaccurate.  All installations must be performed by a licensed contractor i.e. MM1, MM-98, MS1, MS3.  A homeowner can also do the installation provided he/she completes the homeowner training and passes a homeowners test.   All installations must receive a final inspection by the Department before it is activated.  Any unpermitted existing systems must apply for a Certificate of Registration from the Department.

Lot Size Requirements: The lot size requirements apply to conventional systems that discharge to the soil.

A conventional system shall not be installed on a lot less than 0.75 acres where there is not an established on site disposal system, except as provided under Section 301.F.

The design flow for a conventional disposal system shall not exceed 500 gallons per acre.  Lot size X 500 = design flow allowed for that piece of property.   For lots that exceed 500 gallons per acre or lots that do not meet minimum lot size, advanced/alternative systems that reduce Total Nitrogen (TN) per Section 603 may be approved.

On-site systems installed after the effective date of the Regulations (9/1/05) on lots recorded prior to February 1, 1990 shall:  If between 0.5 and .075 acres and the depth to groundwater exceeds 101’, may be approved until Sept1, 2007.  If the lot is between 0.5 and 0.75 acres and the depth to ground water exceeds 600’ may be approved until September, 2010.

* Date of record is the date of legal recording in the county clerk’s office or for subdivision having received                      final approval date of record shall be 2 ½ years from the date of final governmental approval.

* Roadways easements cannot be included as part of the lot size.

*43,560 square feet = 1 acre

Design Flow: The design flow established for residential homes is as follows:

1 bedroom = 150 gallons per day

2 bedroom = 300 gallons per day

3 bedroom = 375 gallons per day

4 bedroom = 450 gallons per day

5 bedroom = 525 gallons per day

Any room that meets the definition of a bedroom (door which provides for privacy and a window that can be utilized as a fire escape) will be considered a bedroom and calculated into the design flow.  Bathrooms are not calculated into the design flow.

For multiple units on a property such as a duplex or guest house, the flow for each home must be added together to determine the total flow.

For commercial discharges refer to Table 201.1 of the New Mexico Liquid Waste Regulations.

Rental spaces for mobile homes will be calculated as three bedrooms.

Setback Requirements: Setback distances apply to any part of the on-site liquid waste system and its designated replacement area:

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	--	5 ft.	5 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	--	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 4 feet.

(4) **** Plus 2 feet for each additional foot of depth in excess of 1 foot below perforated pipe.

(5) ***** May be 5 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 seasonal high water flow 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.

[20.7.3.302 NMAC - Rp, 20.7.3.303 NMAC, 9/1/05]

Clearance Requirements: 4 feet of suitable soil is required between the bottom of an absorption area and high water table or bedrock.   A reduction in this clearance may be allowed with appropriate advanced treatment or alternative disposal such as a mound system.  Holding tanks (no discharge) may be allowed in these circumstances.

Treatment Units: Conventional treatment units must be certified by the Department for use (ask for a list).   All tanks shall be watertight.  Tanks installed after 1976 must have a baffle.  All manholes on new installations must have risers to grade with secure lids.  A secure lid shall consist of the following:  A pad lock, a twist lock cover requiring special tools for removal, covers weighting 58 pounds or more, and a hinge and hasp mechanism, other mechanisms approved by NMED.  All new installations require effluent filters.  Tanks must be 2.5 times the design flow of the home.

All advanced treatment units must be approved for use by the NMED.  Ask for list. Advanced treatment units installed to meet a lot size constraint will be permitted with conditions such as maintenance contracts, monitoring of effluent etc.

Holding tanks must be 4 times the design flow of the home, be water tight, have alarm systems, and pumping records must be provided to the Department.

All installations must be installed in accordance with manufacturer’s requirements.

Absorption Field: Conventional drain fields/leach field shall be allowed in suitable soils only.  Suitable soil is determined by a ribbon test or percolation test.  Square footage required for residential units are calculated as follows:  Design Flow X 2 = Required Square Footage.  For example a one bedroom home (150 gpd) requires 300 square ft.  A two bedroom (300 gpd) requires 600 square ft.  etc.  Extremely clayey soils shall be calculated as follows: Design Flow X 5 = Required Square Footage. Soils that percolate too fast (course sand) will require secondary treatment/disinfection provided the water table is greater than 30 feet.

Trenches:   Shall be no longer that 150 ft.  Total depth to trench bottom can be no more than 6 feet.  4’ of suitable soil below the trench is required.   End caps must be placed on all distribution lines.  Capped inspection ports are to be installed at the end of each trench and brought to grade.  If more than one trench is being installed a T must be utilized.  A distribution box is required if more than two trenches are being installed. Pressure dosing shall be utilized if more than 500 linear ft of leach line is required.  Pipe/Infiltration shall be level.  Aggregate shall be ¾ in to2 ½ inch in size.  A maximum of 3 ft of aggregate is allowed below the pipe.  Trenches shall to 4 ft apart edge to edge.  For any additional ft of gravel (in excess of 1 ft) 2 ft of separation must be added.  Infiltrators must be 7 ft apart center to center.

The length of a trench for pipe and gravel can be calculated by dividing the square footage required by the credit given per sq ft/linear ft.

Trench is:        1’ wide trench              2’wide              3’wide

Gravel under pipe is:               1’                     2 credits                      3 credits          4 credits

1.5                   3 credits                      4 credits          5 credits

2                      4 credits                      5 credits          6 credits

2.5                   5 credits                      6 credits          7 credits

3                      6 credits                      7 credits

For example a trench that 2 ’wide with 2’ of gravel under the pipe requiring 750 sq ft of absorption would be calculated:  750(sq ft required)  divided by 5 (credits) = 150 linear feet of trench.

A trench that is utilizing chamber units varies in credit given per unit.  (Ask for list)  Infiltrators (High Capacity Quick 4) are awarded 19.3 sf/unit.  High Capacity 6 ft units are awarded 30 sf/unit.  Divide square footage required by 19.3 or 30 to calculate the number of units required.

It is recommended that liquid waste systems not be placed underneath roadways.

Two residences can discharge into one liquid waste system provided lot size requirements are met and the system is designed accordingly.   Well splits must be registered with the State Engineers Office (827-6120).

Liquid waste shall be disposed of on the same piece of property on which it is generated.

Grey Water Systems: Gray water with discharges less than 250 gallons per day of private residential gray water will be allowed if it can meet required conditions of the Regulations.

Split flow systems are credited with an 80 percent nitrate reduction.

Property Transfer: An inspection of the system must undergo a Transfer of Ownership inspection by a licensed installer or a NAWT certified party at time of sale.

In Conclusion: If you have further questions or concerns you may contact the Taos Field Office staff at (505) 758-8808 or our Liquid Waste Specialist at (505) 753-7256.  You may also obtain information or forms from our website:  www.nmenv.state.nm.us under the liquid waste tab.

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