Current through Register Vol. 42, No. 11, August 30, 2024
(1)
Concrete Tanks. These tanks
shall be designed, constructed, and tested in accordance with the most recent
American Society for Testing and Materials (ASTM) C1227 standard.
(a) Cast in-place tanks shall have a minimum
wall, bottom, and lid thickness of standard.
(b) Precast concrete tanks with capacities of
less than 1,200 gallons shall have a minimum lid thiclmess of 3 inches, and
tanks with capacities of 1,200 gallons or more shall have a minimum lid
thickness of 4 inches.
(c) Concrete
tank lids shall have a minimum 6-inch by 6-inch (6-inch on centers of number 10
gauge) welded steel reinforcement or meet the current ASTM standard.
1. A lid for a tank may be monolithically
poured. The lid for a tank with an effective liquid capacity of less than 1,200
gallons shall have only one section. A larger tank lid may have more than one
section. In no case shall it be necessary to remove a lid or lid section in
order to gain access to a tank for inspection or maintenance purposes. Where
more than one lid section is used, joints between sections shall be watertight.
Except for a monolithic pour or a proprietary product design, an approved water
stop shall be used to affix the lid to the tank body or to seal multiple-part
tank bodies.
(2)
Non Concrete Tanks. These
tanks shall be designed, constructed, and tested in accordance with the most
recent IAPMO/ANSI ZlOOO standard.
(3)
Risers. Risers for tanks
shall be cast/incorporated directly into tank lids or tops. Risers shall be
manufactured of material-a that are compatible with the expansion and
contraction of tank material and form a mechanical bond with the tank material,
ensuring a watertight seal.
(a) Risers shall
be located, at a minimum, over the inlet and outlet structures and shall be a
minimum of 18 inches in diameter.
(b) All risers and components shall have
watertight covers or lids. The cover or lid shall be designed, constructed, and
maintained to prevent unauthorized access.
(c) A plastic or fiberglass access riser and
cover or lid shall have third-party documentation that ultra-violet (UV)
protection is molded into all components.
(4)
Traffic Rated. Whenever
vehicular traffic is anticipated to cross over a tank, traffic lids shall be
installed with traffic rated risers to finished grade.
(a) Tanks and lids shall be designed in
accordance with the appropriate ASTM standard for the appropriate
loading.
(b) Any tank lid certified
by the engineer to meet the appropriate American Association of State Highway
and Transportation Officials (AASHTO) H-20 Loading Criteria may be approved by
ADPH. Access inspection openings with a minimum 18-inch diameter or equivalent
area opening shall be provided in the tank lid or top over the area of the
inlet and outlet structures.
(5)
Tank Sizing. The effective
liquid capacity of a septic tank for a dwelling shall be based on the number of
bedrooms proposed and shall, at a minimum, comply with Table 9.
(a) The effective liquid capacity of a septic
tank for an establishment without advanced treatment shall be based on flow
computed per
420-3-1-.52 Design Flow and
Wastewater Concentrations, and shall have a minimum hydraulic detention time of
48 hours for tanks (i.e., septic tanks and grease traps), or combinations of
tanks in series, In no case shall the tank effective liquid capacity be less
than 1,000 gallons.
(6)
Other. If a trash trap is requited by the OSS/EDS designer or
manufacturer, the trash trap shall meet the structural requirements of this
rule. When recommended or required by the advanced treatment system
manufacturer or the engineer, a sewage trash trap or septic tank preceding an
advanced treatment unit shall meet the design requirement of the advanced
treatment system manufacturer. The effective liquid capacity of the trash trap
shall meet the advanced treatment manufacturer requirements.
(a) Septic tanks installed at individual
dwellings as part of a Large-Flow Cluster System shall confopn to the
construction and inspection requirements of the Minimum Construction and
Testing Standards for Cluster and Community Wastewater Systems.
(b) The use of metal tanks, drums, barrels,
or pipes as sewage tanks is prohibited for use with onsite sewage disposal
systems.
Previous Rule .27 was renumbered .17 per certification
published December 30, 2022; effective February 13,
2023.
Author: Thad Pittman, Matthew Conner, Ken
Stephens, Bob Bright
Statutory Authority:
Code of Ala.
1975, §§
22-2-2(4);
22-2-2(6);
22-10-1, et
seq.; 22-26-1, et seq.
