1. A. The required level of treatment shall be based on the most restrictive combination of siting conditions.

2. B. The following treatment levels are required for the soil types as described in Table 703.1:

   (1) type Ia - secondary treatment and disinfection except as noted in Subsection F of 20.7.3.703 NMAC;

   (2) type Ib, II, and III - primary treatment; and

   (3) type IV - primary treatment with an appropriate disposal method as approved by the department.

3. C. The following treatment levels are required for the depth of suitable soil:

   (1) greater than or equal to four feet of suitable soil - primary treatment;

   (2) one to less than four feet of suitable soil - secondary treatment and disinfection; and

   (3) no discharge with less than one foot of suitable soil to groundwater, karst or fractured bedrock.

4. D. The following treatment levels are required for hydraulic loading rates and lot size:

   (1) less than or equal to 500 gallons per day per acre with a minimum lot size of 0.75 acre - primary treatment; and

   (2) greater than 500 gallons per day per acre or less than 0.75 acre - tertiary treatment;

   (3) for lots less than 0.75 acre overlaying anoxic groundwater, secondary treatment shall be required and tertiary treatment may be required; to be exempt from tertiary treatment requirements, the permit applicant shall show by clear and convincing evidence that the discharge of liquid waste shall not degrade a body of water.

5. E. The following are requirements for a reduction in the disposal field setback distance, as set forth in Table 302.1:

   (1) Tertiary treatment and disinfection are required for any reduction in setback distance between 50 feet and less than 100 feet from a private drinking water well located on the subject property.

   (2) A variance is required and tertiary treatment and disinfection are required for any reduction in setback distance to:

   (a) any private drinking water well located on the subject property less than 50 feet from the disposal system;

   (b) any private drinking water well not located on the subject property; or

   (c) any public drinking water well.

6. F. A non-discharging system may be used in lieu of advanced treatment.
7. G. A mound system or elevated system in accordance with 20.7.3.806 NMAC may be used to meet clearance requirements or to overcome soil type limitations in lieu of advanced treatment. A sand-lined trench or bottomless sand filter in accordance with 20.7.3.812 NMAC may be used to meet clearance requirements in lieu of advanced treatment.
8. H. If the existing level of nitrate-N in the groundwater exceeds 5 mg/l, more stringent requirements pursuant to Subsection L of 20.7.3.201 NMAC may be required.

[20.7.3.605 NMAC - Rp, 20.7.3.605 NMAC, 9/1/13; A,9/1/13]