N.M. Admin. Code § 20.7.8.200

Current through Register Vol. 35, No. 23, December 10, 2024

Section 20.7.8.200 - SUBPART II FORMULA AND FACTORS

A. Formula: The basic formula is: priority rating number = S (P) + Q + W

B. Factors: The formula factors S, P, Q and W are:

(1) S = severity of pollution or public health factor;

(2) P= population factor;

(3) Q = water quality preservation factor;

(4) W = absence or presence of community water system factor.

C. Severity of Pollution or Public Health Factor(s): This factor ensures that limited construction funds are utilized first to reduce significant existing water pollution or public health problems that cannot be solved by adequate operation and maintenance (O&M). Assignment of values shall be done by the New Mexico Environment Department (NMED) using data from water quality studies conducted by NMED, review and verification of data from other sources including data on adequacy of O&M, or environmental surveys conducted by NMED. Only one value (the highest) shall be assigned to a project.

(1) Surface Water: Discharges to surface water shall be rated on the basis of their demonstrated impact on the quality of a receiving stream, lake, or impoundment. Values will be assigned according to compliance with numerical or general standards established for the receiving water in the latest edition of "State of New Mexico Standards for Interstate and Intrastate Stream" 20 NMAC 6.1 [20.6.1 NMAC]. The value shall be:

(a) 10- if the discharge is causing violation of two or more stream standards (other than fecal coliform);

(b) 8- if the discharge is causing violation of one stream standard (other than fecal coliform);

(c) 6- if the discharge is causing violation of the stream standard for fecal coliform only;

(d) 4- if the discharge is not in compliance with NPDES permit discharge parameters;

(e) 3- if the project consists primarily of construction of a wastewater treatment facility and none of the above conditions can be demonstrated;

(f) 2- if the project consists primarily of construction of an interceptor or lift station and none of the above conditions can be demonstrated;

(g) 1- if the project consists primarily of construction of a collection system and none of the above conditions can be demonstrated.

(2) Groundwater: Discharges onto or below the surface of the ground shall be rated on the basis of demonstrated groundwater contamination or violation of groundwater protection regulations. If inadequate well construction is identified as a significant contributing cause of a contamination problem, points will be assigned in this category only when modification of the wastewater treatment method is the most cost-effective solution. The value shall be:

(a) 12- if a total nitrogen (as N) concentration greater than 10 mg/l is demonstrated in a public water supply well where a municipal discharge is the probable cause of this condition;

(b) 10- if a total nitrogen (as N) concentration greater than 10 mg/l is demonstrated in 10% of the private water supply wells within the zone of influence of a municipal discharge where the municipal discharge is the probable cause of this condition. For this category, only wells used primarily as a domestic water supply will be considered;

(c) 8- if, in an area of groundwater contamination where the probable cause of this condition is on-site waste disposal systems, total nitrogen (as N) concentrations greater than 10 mg/l are present in a public water supply well or in more than 10% of the private water supply wells in the total unsewered portion of the project planning area. When this value is assigned to projects consisting primarily of new interceptor or collection systems, only the area and populace to be serviced by the proposed interceptor or collection system shall be considered in establishing severity of pollution or public health (S) and population (P) factors.

(d) 6- if there is existing or projected noncompliance as determined by the NMED with standards for groundwater as that established by Water Quality Control Commission Regulation, 20 NMAC 6.2.3103 [20.6.2 NMAC] and a municipal discharge or septic systems are the probable cause of this noncompliance. Projected noncompliance with Water Quality Control Commission Regulation, 20 NMAC 6.2.3103 [20.6.2 NMAC] should be demonstrated through the use of accepted predictive hydrologic models used in conjunction with on-site monitoring data.

(e) 3- if the project consists primarily of construction of a wastewater treatment facility and none of the above conditions can be demonstrated.

(f) 2- if the project consists primarily of construction of an interceptor or lift station and none of the above conditions can be demonstrated.

(g) 1- if the project consists primarily of construction of a collection system and none of the above conditions can be demonstrated.

D. Population Factor (P): This factor is a multiplier based on the estimated population, Bureau of Census figures projected to current calendar year, of the wastewater facilities planning area.

For a population estimate of: The factor shall be:

Less than 500 1.5

500 - 999 2.0

1,000 - 4,999 3.0

5,000 - or over 3.5

E. Water Quality Preservation (O): This factor considers the need for preservation of those surface waters in New Mexico which are the most suitable for recreation and support of desirable aquatic life or for groundwater which has an existing concentration of 10,000 mg/l or less of total dissolved solid (TDS), for present and potential future use as domestic and agricultural water supply, and to protect those segments of surface waters which are gaining because of groundwater inflow. Values shall be assigned only to existing surface or groundwater discharges and only one value (the highest) shall be assigned to each project. Designated uses listed in Subpart 2 of the latest edition of the "State of New Mexico Standards for Interstate and Intrastate Stream" 20 NMAC 6.1 [20.6.1 NMAC] shall apply. The value shall be:

(1) 8- if the discharge is to a stream with designated beneficial uses of primary contact recreation or high quality cold water fishery or if there is a reservoir or permanent pool within 25 miles downstream of the discharge; or if the discharge is to groundwater which lies within 20 feet of the surface or which will be negatively impacted by the discharge as evaluated by the NMED;

(2) 6- if the discharge is to a stream with a designated beneficial use of cold water fishery; or if the discharge is to groundwater which lies within 40 feet of the surface;

(3) 4- if the discharge is to a stream with designated beneficial uses of marginal cold water fishery or warmwater fishery; of if the discharge is to groundwater which lies within 60 feet of the surface; or;

(4) 2- if the discharge is to a stream with designated beneficial uses of secondary contact recreation or limited warmwater fishery; or if the discharge is to groundwater which lies below 60 feet of the surface.

F. Absence or Presence of Community Water System Factor (W): This factor considers the risks associated with the community's dependency on on-site domestic water wells which would normally be at greater risk of being contaminated by on-site liquid waste disposal systems than community water supply systems. The value shall be:

(1) 4- absence of community water system; or

(2) 0- presence of community water system.

N.M. Admin. Code § 20.7.8.200

2/28/93, 11/30/95; 20.7.8.200 NMAC - Rn, 20 NMAC 7.8.II.200, 201, 202, 203, 204, 205, Recompiled 11/27/01