Groundwater Well Decommissioning in Midpeninsula Open Space Preserves
Summary
SCH Number
2022120494
Public Agency
Midpeninsula Regional Open Space District
Document Title
Groundwater Well Decommissioning in Midpeninsula Open Space Preserves
Document Type
NOE - Notice of Exemption
Received
Posted
12/20/2022
Document Description
Midpeninsula Regional Open Space District (District) Preserves contain extensive groundwater systems. The District’s acquisition and restoration of domestic land parcels in the Preserves has resulted in abandoned wells. To protect water quality in California, inactive wells are decommissioned to reduce the potential for the transfer of surface contaminants to groundwater. The District has followed state and county regulations to properly decommission 10 wells since spring 2021.
The District has identified 37 remaining wells in the Open Space Preserves (Figures 1 and 2) that meet Santa Clara Valley Water District’s (Valley Water) and San Mateo County Health Groundwater Protection Program’s definitions of abandonment and require decommissioning. Beginning summer 2023, the District will contract with a C-57 licensed drilling company to continue decommissioning wells in Open Space Preserves across the mid- to northern Santa Cruz Mountains Region. The drilling company will work with the counties to obtain permits and to assess how to appropriately decommission each of the wells, which could vary based on the geologic setting, well type, and other factors that influence decommissioning protocols. Trucks will be used to prepare the wells for decommissioning, and a cement truck or crew using hand tools will fill each well casing with a cement-based mixture to a depth compliant with county regulations—typically from the bottom of the well to 5 feet below ground surface. The remaining casing, pump, cement pad, and wellhead will be removed. The small (5 foot by 5 foot) disturbance area will be leveled, and soils will be left at-grade.
Most of the abandoned wells are adjacent to established roads. None of the work will impact streams or ephemeral channels, and minor vegetation removal will be limited to clearing existing roads that lead to the well sites. Biological surveys conducted prior to each well’s decommissioning will ensure the avoidance of rare plant species, bird nesting, and bat habitat. There are no known contaminants or septic tanks near the wells.
Contact Information
Name
Jared Hart
Agency Name
Midpeninsula Regional Open Space District
Job Title
Senior Planner
Contact Types
Lead/Public Agency / Project Applicant
Phone
Email
Location
Cities
unincorporated area
Counties
San Mateo, Santa Clara
Regions
San Francisco Bay Area
Other Location Info
Midpeninsula Regional Open Space District Preserves in Santa Clara and San Mateo counties
Notice of Exemption
Exempt Status
Categorical Exemption
Type, Section or Code
California Code of Regulations, Title 14, Section 15301 Class 1 and Section 15304 Class 4
Reasons for Exemption
Well decommissioning represents minor alterations of existing equipment that would not expand existing or former uses. There will be no removal of healthy, mature, or scenic trees.
County Clerks
San Mateo, Santa Clara
Attachments
Notice of Exemption
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