Current through Register Vol. 35, No. 18, September 24, 2024
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.
