Public Works Storm Water
Review No:1

Application No.: APP-151002                                                       G_V                                       3/02/15

1. Does the site currently receive runoff from upstream?

2. Proposing the driveway runoff and overflow runoff form the rain garden system to discharge onto the county road right of way is not permissible.  Please revise the drainage design, so that runoff can be infiltrated on-site.

A waiver for meeting the Design Standards of this section on the project site can be granted by the Director of Public Works.  In order to receive an on-site waiver, the project applicant must submit a request along with technical documentation describing reason(s) of impracticability.  A waiver of impracticability shall be granted only when all other Structural or Treatment Control BMPs have been considered and rejected as infeasible.  Recognized situations of impracticability include:

i)             extreme limitations of space for treatment on a redevelopment project,

ii)            unfavorable or unstable soil conditions at a site to attempt infiltration, and

iii)           risk of groundwater contamination because a known unconfined aquifer lies beneath the land surface or an existing or potential underground source of drinking water is less than 10 feet from the soil surface.

Off-site compliance with Section 3 of these criteria will be required when technical impracticability limits or prevents compliance with on-site facilities.   Off-site compliance will only be considered after on-site technical impracticability has been demonstrated by meeting the above requirements.  Allowable off-site compliance must be located in the same watershed as the proposed development project, must be located on private property, must be built prior to final construction approval of the proposed development, and must be accompanied by recorded maintenance and easement agreement(s) that guarantee the function and maintenance of the off-site mitigations for the development project lifetime.  Allowance of off-site compliance is subject to approval by the Director of Public Works and the CCRWQCB Executive Officer.

3. Please provide a cross section construction detail for the proposed graded swale.

4. The project designer shall establish specifications and requirements for the ongoing maintenance and monitoring to ensure proper functioning of stormwater management facilities and practices proposed as part of a development application and consistent with County Code 7.79.  A Stormwater Management Maintenance Agreement (SWM25A) shall be recorded by the property owner with the County Recorder’s Office on the deed.

A drainage fee will be assessed on the net increase in impervious area. The fees are currently $1.17 per square foot, and are subject to increase based on the amount applicable at permit issuance date. Reduced fees (50%) are assessed for semi-pervious surfacing (such as gravel, base rock, paver blocks, porous pavement, etc.) to offset costs and encourage more extensive use of these materials.

You may be eligible for fee credits for pre-existing impervious areas to be demolished.  To be entitled for credits for pre-existing impervious areas, please submit documentation of permitted

structures to establish eligibility. Documentations such as assessor’s records, surveys records, or other official records that will help establish and determine the dates

they were built, the structure footprint, or to confirm if a building permit was previously issued is accepted.

 

The applicant is encouraged to discuss the above comments with the reviewer to avoid unnecessary additional routings. A $330.00 additional review fee shall be applied to all re-submittals starting with the third routing.

 

Please call the Dept. of Public Works, Stormwater Management Section, from 8:00 am to 12:00 noon if you have questions.