4) The capacity of the system shall be calculated using the following formula:
Cs = underbrace 10771 A Δ h Δ t
Cs Capacity of the system (gpd)
A Horizontal cross-sectional area (sf)
Δ h Vertical drop (ft) of water level during the test of the well
Δ t Time (minutes) for water level to drop Δ h
Drywells may not be constructed closer than 300 feet to a water well, and may not be deeper than 10 feet above any saturated zone.
The following statement shall appear on all plans which include drywells.
"All drywells shown on this project shall be maintained by the owners where their locations are on private property or through the creation of a Landscape Benefit Assessment District when approved by the City. Drywells will be replaced by the owners when they cease to drain standing surface water in a 24 hour period or are deemed to be obsolete by the City. Regular maintenance of the drywell settling chamber is required to achieve proper operation of the drywell and shall be performed annually or more often depending upon its location, and shall be performed by the owner or district as applicable".
Where subsurface conditions are such that drywells cannot be expected to perform to the minimum standards established herein, alternative disposal methods will be considered by the City. The location of suitable sites for disposal, even if off-site, is encouraged. The effectiveness of the offsite disposal areas must be demonstrated.