Section 18 AAC 72.270 - Collection and pumping systems(a) Plans for construction of a collection and pumping system must include (1) the items required to be submitted under 18 AAC 72.205;(2) plans and profiles for sewer mains and community sewer lines to include manholes and lift stations with invert elevations;(3) design calculations, design criteria, and specifications for (A) design flows, pipe size, and pipe materials;(B) hydraulic grade line considerations associated with pressurized portions of a sewer line;(C) vacuum sewer lift segments;(D) pump station, collection station, or surge tank capacities;(E) overflows, alarms, solids handling, provisions for servicing, and emergency operations;(F) manhole or cleanout placement, and methods for cleaning the collection system;(G) siting with respect to health hazards, nuisance potential, stream crossings, and flooding;(H) bedding and backfill;(I) thermal protection considerations; and(J) provisions for steep slope and high velocity protection if applicable.(b) A collection and pumping system design must include the following criteria:(1) the mean conduit velocity, when flowing full, is not less than two feet per second for the collection system design;(2) pipe sizes adequate for the maximum expected flow and designed so that the diameter of any receiving sewer line is equal to or greater than the diameter of the largest sewer line connecting to it;(3) the alignment of a gravity sewer line between manholes shall be straight and at a uniform slope; a manhole must be installed at changes in pipe slope, size, alignment, and at intersections;(4) the location meets the minimum separation distance requirements (A) under 18 AAC 80 for public water systems unless the department has approved a lesser separation distance under that chapter;(B) under 18 AAC 72.100 for private water systems unless the department has approved a lesser separation distance under this chapter; and(C) of 100 feet between the mean annual high water level of a lake, river, stream, spring, or slough, or the mean higher high water level of tidally influenced coastal waters and a tank, lift station, or sewer manhole, measured horizontally from nearest edge to nearest edge;(5) pump stations and collection stations, other than those designed for pumping from individual service connections or onsite septic tanks, must be equipped with at least two pumps, each of which can handle flows equal to or in excess of the design flow;(6) pump stations must be equipped with an audible and visual high water alarm;(7) the system does not receive stormwater or silty water from construction dewatering efforts, gutter runoff, or street runoff into a sewer designed to handle only domestic wastewater or nondomestic wastewater without stormwater;(8) the system discharges to an approved wastewater treatment works with adequate capacity;(9) the system does not collect oil, petroleum products, industrial solvents, or other substances (A) into a sewer designed to handle only domestic wastewater or stormwater; or(B) that will be received by a treatment works or disposal system that is not designed and approved to handle these substances; and(10) if proposing to discharge to an existing collection system, documentation must be provided showing that(A) the receiving system has sufficient capacity to accommodate flows expected from the proposed discharge;(B) the receiving system is permitted or approved to accept the type of wastewater proposed; and(C) the owner of the receiving system has approved the discharge.Eff. 4/1/99, Register 149; am 10/1/2023, Register 247, October 2023Authority:AS 44.46.020
AS 46.03.010
AS 46.03.020
AS 46.03.050
AS 46.03.100
AS 46.03.110