(A) This section outlines the requirements for sizing flow control facilities. The flow control standards are based on the Stormwater Management Manual for Eastern Washington and the Spokane County Stormwater Manual.
(1) Standard flow control facilities are detention, retention (natural depressions) and infiltration facility.
(2) Any other facility is considered a non-standard system and shall be evaluated individually by the City PWD.
(3) Flow control facilities are necessary to mitigate potential adverse impacts on down-gradient properties due to the increase in stormwater run-off caused by land development.
(B) (1) The peak rate of stormwater run-off from any proposed land development to any natural or constructed point of discharge downstream shall not exceed the pre-development peak rate of run-off.
(2) The post development volume of run-off can exceed the pre-development volume of run-off when the required down-gradient analysis demonstrates that there will be no adverse impacts on down gradient properties or existing natural and constructed conveyance systems.
(Prior Code, § 11.05.040.060) (Ord. 2019-9, passed 9-3-2019; Ord. 2021-15, passed 12-20-2021)