University of California, Davis
IN-36: Stormwater Modeling

UC Davis uses the California State Water Board Calculators, which are spreadsheets provided by the state, to track the impact of Low Impact Development (LID) practices and green infrastructure on campus. The spreadsheet calculator requires the user to fill in information about infrastructure area (pavements, trees, roofs, etc.) and county/location data into the various tabs, and then the volume calculator tab calculates the local/regional rainfall and stormwater run-off. Some projects on campus also use the online tools provided by Central Coast Low Impact Development Initiative (LIDI). The website provides a tool for inventory, assessment, prioritization and tracking of structural Best Management Practices (BPM) and a tool for estimating municipal stormwater volume and pollutant loading to receiving waters.

Stormwater Modeling is a concept that is built into the foundational requirements for the UC Davis campus. The California Municipal Separate Storm Sewer System (MS4) Phase II permit contains regulations for new development and redevelopment projects. The goals of the post-construction requirements are to 1) prevent storm water impacts from new development and redevelopment projects; and 2) prevent additional runoff from increased impervious area by mimicking natural processes for storm water. This is accomplished by requiring LID and source control measures to be incorporated into design, construction, and operation & maintenance (O&M).

UC Davis complies with these requirements by:

(1) Requiring all new constructions projects to comply with the current MS4 permit, by incorporating the requirements into the Construction Standards Design Guideline, Part II, Storm Drainage and Part IV, Specification 01 57 23.

(2) If projects exceed the threshold of 2,500 square feet of impervious surface, one of the following checklists is required to be filled out and submitted to EH&S (Environmental Health & Safety):

a. Post-Construction Storm Water Management Checklist (2,500-5,000 sq ft)

b. Post-Construction Storm Water Management Checklist (>5,000 sq ft)

(3) The checklist and plans will be reviewed by EH&S and any required changes to meet the requirements will be communicated to project managers.

(4) Once projects are completed, EH&S will document that the post-construction measures are in place and that O&M requirements are delegated.

Additionally, storm water modeling is built into the UC Davis Long Range Development Plan (LRDP), a result of a multi-year effort to understand the needs of the campus and challenging societal issues and identify strategic improvements and projects. Chapter II – Campus History & Stewardship of the LRDP explains that campus built systems have integrated in the past and will continue to integrate storm water treatment basins throughout campus to reduce flood impact, improve water quality, recharge local aquifers, and integrate drought-tolerant landscapes across the campus. Chapter IV – Land Use Planning asserts that the UC Davis Arboretum and Public Garden plan to progress the integration of storm water treatment features into the campus landscape; for example, by incorporating ecosystems functions and using rainwater collection as an alternative water source for seasonal irrigation.

Link to the CA State Water Board Calculator (Appendix 2.1 Post-Construction Water Balance Performance Standard): https://www.waterboards.ca.gov/water_issues/programs/stormwater/constpermits.shtml

UC Davis Design Requirements Link: https://dcm.ucdavis.edu/2018-campus-design-guide

UC Davis Long Range Development Plan: https://campusplanning.ucdavis.edu/campus-planning/2018-ucdavis-lrdp

Central Coast LIDI tool link: https://www.centralcoastlidi.org/mspap.php