Current through Register Vol. 35, No. 6, March 26, 2024
A. Plans for treatment units that have not
been previously approved by the department, including septic tanks, shall be
submitted to the department for approval and certification. Such plans shall
show all dimensions, reinforcement, structural calculations and such other
pertinent data as may be required by the department. Plans for advanced
treatment units shall be submitted to the department for review by the
wastewater technical advisory committee pursuant to 20.7.3.905 NMAC. Plans for
advanced treatment units that have not been previously approved by the
department shall meet the requirements set forth by the wastewater technical
advisory committee. All plans shall be stamped by a professional engineer.
(1) Septic tanks shall be recertified on an
annual basis. A recertification fee is required pursuant to 20.7.11.9 NMAC.
Failure to recertify shall result in the suspension of department
approval.
(2) Failure of the
manufacturer of an advanced treatment unit to comply with the conditions of
approval by the department shall result in non-approval or suspension of
department approval for the advanced treatment unit.
B. All treatment units and tanks, regardless
of material or method of construction and unless otherwise specified in 20.7.3
NMAC, shall:
(1) be designed and constructed
to withstand all reasonable lateral earth pressures under saturated soil
conditions with the tank empty;
(2)
support a minimum live load at the surface of 300 pounds per square foot with
three feet of cover unless heavier loads are expected;
(3) not be subject to excessive corrosion or
decay;
(4) have the manufacturer's
name, New Mexico registration number, year of construction and tank capacity in
gallons permanently displayed on the tank above the outlet pipe;
(5) be watertight;
(6) not be constructed or manufactured on
site, in the ground, when saturated soil conditions during construction are
closer than three inches to the bottom of the excavation;
(7) be protected against flotation under high
groundwater conditions and for units installed in floodplains;
(8) be installed so that they are easily
locatable and accessible;
(9) be
approved by the international association of plumbing and mechanical officials
(IAPMO); or meet IAPMO minimum standards as demonstrated to the department by
approved laboratory testing; or meet all requirements of 20.7.3.501 and 502
NMAC as certified by a professional engineer; or be recommended by the
wastewater technical advisory committee and approved by the department;
and
(10) all access risers shall be
attached to the treatment unit with a watertight or water resistant
seal.
C. Treatment units
may be constructed of the following materials:
(1) precast reinforced concrete;
(2) poured-in-place concrete;
(3) fiberglass;
(4) polyethylene; or
(5) other materials as approved in writing by
the department.
D.
Metal, wooden, concrete block and homeowner built tanks are
prohibited.
E. A secure lid shall
consist of one or more of the following:
(1) a
padlock;
(2) a twist lock cover
requiring special tools for removal;
(3) covers weighing 58 pounds or more, net
weight;
(4) a hinge and hasp
mechanism that uses stainless steel or other corrosion resistant fasteners to
fasten the hinge and hasp to the lid and tank for fiberglass, metal or plastic
lids; or
(5) other mechanisms
approved by the department.
F. Wherever vehicular traffic is anticipated
to cross over the liquid waste treatment unit, pump station or pump chamber,
the unit shall be designed by a professional engineer to withstand the
anticipated traffic loading.
G. All
solid wall pipe connections, fittings and penetrations shall be
watertight.
H. Each tank shall be
structurally designed to withstand all anticipated earth or other loads. All
septic tank covers shall be capable of supporting an earth load of not less
than 300 pounds per square foot when the maximum fill coverage does not exceed
three feet. All access risers covers shall be capable of supporting a live load
of not less than 300 pounds per square foot.
I. Fiberglass or reinforced plastic septic
tanks shall be certified to IAPMO standards. Fiberglass or plastic septic tanks
shall be installed according to the manufacturer's instructions. A copy of the
manufacturer's installation instructions shall be available for inspection by
the department at the installation site.
J. Concrete liquid waste treatment units.
(1) Minimum concrete thickness.
(a) walls: two and one-half inches in
thickness.
(b) floors: three inches
in thickness.
(c) covers: three
inches in thickness.
(2)
Floors shall be an integral part of the tank.
(3) Where sections are used, tongue and
groove joints or keyways shall be used and shall be sealed with an approved
sealer and shall be watertight.
(4)
Poured-in-place tanks shall be designed and certified by a professional
engineer.
(5) All concrete liquid
waste treatment units, except those approved for use utilizing concrete meeting
type V specifications, shall be protected from corrosion by coating internally
with an approved bituminous coating or by other acceptable means. The coating
shall cover all exposed concrete and shall extend to at least six inches below
the waterline.
(6) Treatment unit
construction materials shall meet the following minimum specifications:
(a) concrete strength - 3500 psi @ 28 days,
density 140 PCF;
(b) cement
Portland type II or V per the latest version ASTM specifications;
(c) admixtures per the latest version of ASTM
specifications; and
(d) reinforcing
per the latest version of ASTM specifications for steel bars, grade 40/60 or
equivalent.
(7) Be
installed level on undisturbed or compacted soil, 1/4 to 3/4 inch pea gravel or
sand.
