Attachment_H_Admin_Memo_B-31_-_Policy_for_the_Operation_and_Maintenance_of_County_Stormwater_Control_Measures.pdf

ADMINISTRATIVE MEMORANDUM

COUNTY OF SAN MATEO

NUMBER: B-31

SUBJECT: Policy for the Operation and Maintenance of County Stormwater Control Measures

RESPONSIBLE DEPARTMENT: County Parks and Department of Public Works

DATE: :a (lov~--l

Purpose Provision C.3.h of National Pollutant Discharge Elimination System ("NPDES") Permit No.

CAS612008 requires a legally-enforceable mechanism assigning operation and maintenance ("O&M") responsibility for regulated projects. This Administrative Memorandum shall serve as the legally enforceable mechanism assigning responsibility to the County of San Mateo ("County") for operation and maintenance of County-constructed and/or maintained Stormwater Control Measures ("County Stormwater Control Measures"). This includes County Stormwater Control Measures at regulated sites, which includes: regulated projects, offsite locations, and joint or regional projects as defined by Provision C.3.b.; and non-C.3 regulated projects that the County pursued voluntarily. An example of a County Stormwater Control Measure is a bioretention basin that treats stormwater runoff from the roof of a County facility. Typical maintenance includes irrigation, pruning, weeding, replacement of biofiltration media, and trash and sediment removal.

Background The San Francisco Bay Regional Water Quality Control Board ("Water Board") adopted Order No. R2-2015-0049 (Permit No. CAS612008) San Francisco Bay Municipal Regional Stormwater Permit ("MRP"). The MRP regulates the discharge of stormwater runoff from municipal separate storm sewer systems ("MS4s") for 76 agencies, including the County. The MRP allows the County to operate its MS4, which captures and discharges stormwater to local surface water bodies, such as creeks, rivers, and engineered drainages, under the applicable provisions of the MRP. The MS4 includes all pipes, channels, or other conveyances built to convey stormwater. The County Stormwater Control Measures include all structures, improvements, and vegetation provided to control the quantity and quality of conveyed stormwater.

Policy Provision C.3.h of the MRP requires the County to operate and maintain County Stormwater Control Measures for the life of those systems. The County shall operate and adequately maintain County-constructed or maintained Stormwater Control Measures in conformance with the plans and specifications as designed and installed in compliance with the MRP. Adequate maintenance is herein defined as maintaining the described control measures in good working condition so that these control measures continue to operate as originally designed and approved. The as-built design and related maintenance documents shall include an estimate of annual maintenance costs and staff time and shall be filed with the County Office of Sustainability and the department tasked with maintaining the control measures, for reference during maintenance.

As a resource, the San Mateo Countywide Water Pollution Prevention Program created a Green Infrastructure Design Guide. Chapter 6 includes guidance on maintenance and inspection procedures, and best practices. The guide can be found on the website www.flowstobay.org.

RESOLUTION NO. 077967

BOARD OF SUPERVISORS, COUNTY OF SAN MATEO, STATE OF CALIFORNIA

RESOLUTION AUTHORIZING AND DIRECTING THE COUNTY MANAGER TO

ESTABLISH A POLICY FOR THE OPERATION AND MAINTENANCE OF COUNTY

STORMWATER CONTROL MEASURES

RESOLVED, by the Board of Supervisors of the County of San Mateo, State of

California, that

WHEREAS, the San Francisco Bay Regional Water Quality Control Board's

Municipal Regional Permit (MRP) regulates stormwater discharges from municipal storm drain systems throughout San Mateo County; and

WHEREAS, the County is committed to complying with, and has complied with, the requirements of the MRP; and

WHEREAS, on September 17, 2019, this Board of Supervisors adopted

Resolution No. 076876 approving a Green Infrastructure (GI) Plan for the unincorporated County and County facilities, committing the County to install GI measures identified in the GI Plan where practicable for all County facilities and in the public right-of-way to improve water quality in the San Francisco Bay; and

WHEREAS, Provision C.3.h of the MRP requires a legally enforceable mechanism assigning operation and maintenance responsibility for regulated stormwater treatment measures; and

WHEREAS, the County currently owns and maintains stormwater treatment measures across multiple County facilities and in the public right-of-way; and

WHEREAS, a Policy for the Operation and Maintenance of County Stormwater

Control Measures is the preferred mechanism for assigning operation and maintenance responsibility for stormwater treatment measures owned and/or operated by the County;

and

WHEREAS, the Policy for the Operation and Maintenance of County Stormwater

Control Measures has been jointly developed by San Mateo County staff from the Office of Sustainability, Planning and Building Department, Department of Public Works, and the Parks Department.

NOW THEREFORE, BE IT RESOLVED that the County Manager is hereby authorized and directed to establish a Policy for the Operation and Maintenance of

County Stormwater Control Measures, and the Clerk of the Board shall attest the

President's signature thereto.

BE IT FURTHER RESOLVED that the County Manager is further authorized to amend such policy from time to time in the County Manager's discretion in furtherance of the County's compliance with the requirements of the San Francisco Bay Regional

Water Quality Control Board's Municipal Regional Permit.