Arizona Administrative Code › Title 18 - ENVIRONMENTAL QUALITY › Chapter 9 - DEPARTMENT OF ENVIRONMENTAL QUALITY - WATER POLLUTION CONTROL › Article 3 - AQUIFER PROTECTION PERMITS - GENERAL PERMITS › Part A - GENERAL PROVISIONS › Section R18-9-A314 - Septic Tank Design, Manufacturing, and Installation for On-site Wastewater Treatment Facilities

Current through Register Vol. 30, No. 28, July 12, 2024
A person shall not install a septic tank in an on-site
					 wastewater treatment facility unless the tank meets the following requirements:
1. The tank is:
a. Designed to produce a clarified effluent
				  and provide adequate space for sludge and scum accumulations;
b. Watertight and constructed of solid
				  durable materials not subject to excessive corrosion or decay;
c. Manufactured with at least two
				  compartments unless two separate structures are placed in series. The tank is
				  designed so that:
i. The inlet compartment of
				  any septic tank not placed in series is nominally 67 percent to 75 percent of
				  the total required capacity of the tank,
ii. Septic tanks placed in series are
				  considered a unit and meet the same criteria as a single tank,
iii. The liquid depth of the septic tank is
				  at least 42 inches, and
iv. A septic
				  tank of 1000 gallon capacity is at least 8 feet long and the tank length of
				  septic tanks of greater capacity is at least 2 times but not more than 3 times
				  the width;
d.
				  Manufactured with at least two access openings to the tank interior, each at
				  least 20 inches in diameter. The tank is designed so that:
i. One access opening is located over the
				  inlet end of the tank and one access opening is located over the outlet
				  end;
ii. Whenever a first
				  compartment exceeds 12 feet in length, another access opening is provided over
				  the baffle wall; and
iii. Access
				  openings and risers are constructed to ensure accessibility within 6 inches
				  below finished grade;
e.
				  Manufactured so that the sewage inlet and wastewater outlet openings are not
				  smaller than the connecting sewer pipe. The tank is designed so that:
i. The vertical leg of round inlet and outlet
				  fittings is at least 4 inches but not smaller than the connecting sewer pipe,
				  and
ii. A baffle fitting has the
				  equivalent cross-sectional area of the connecting sewer pipe and not less than
				  a 4 inch horizontal dimension if measured at the inlet and outlet pipe
				  inverts;
f. Manufactured
				  so that the inlet and outlet pipe or baffle extends 4 inches above and at least
				  12 inches below the water surface when the tank is installed according to the
				  manufacturer's instructions consistent with this Chapter. The invert of the
				  inlet pipe is at least 2 inches above the invert of the outlet pipe;
g. Manufactured so that the inlet and outlet
				  fittings or baffles and compartment partitions have a free vent area equal to
				  the required cross-sectional area of the connected sewer pipe to provide free
				  ventilation above the water surface from the disposal works or seepage pit
				  through the septic tank, house sewer, and stack to the outer air;
h. Manufactured so that the open space
				  extends at least 9 inches above the liquid level and the cover of the septic
				  tank is at least 2 inches above the top of the inlet fitting vent
				  opening;
i. Manufactured so that
				  partitions or baffles between compartments are of solid durable material
				  (wooden baffles are prohibited) and extend at least 4 inches above the liquid
				  level. The open area of the baffle shall be between one and 2 times the open
				  area of the inlet pipe or horizontal slot and located at the midpoint of the
				  liquid level of the baffle. If a horizontal slot is used, the slot shall be no
				  more than 6 inches in height;
j.
				  Structurally designed to withstand all anticipated earth or other loads. The
				  tank is designed so that:
i. All septic tank
				  covers are capable of supporting an earth load of 300 pounds per square foot;
				  and
ii. If the top of the tank is
				  greater than 2 feet below finish grade, the septic tank and cover are capable
				  of supporting an additional load of 150 pounds per square foot for each
				  additional foot of cover;
k. Manufactured or installed so that the
				  influent and effluent ends of the tank are clearly and permanently marked on
				  the outside of the tank with the words "INLET" or "IN," and "OUTLET" or "OUT,"
				  above or to the right or left of the corresponding openings; and
l. Clearly and permanently marked with the
				  manufacturer's name or registered trademark, or both, the month and year, or
				  Julian date, of manufacture, the maximum recommended depth of earth cover in
				  feet, and the design liquid capacity of the tank. The tank is manufactured to
				  protect the markings from corrosion so that they remain permanent and readable
				  for the operational life of the tank.