University of California, Davis
OP-22: Rainwater Management

The Campus Design Guide articulates a set of design and construction measures to minimize post-construction storm water runoff volume and manage construction impacts on storm water quality. A wide variety of techniques are used: bioswales; detention and retention basins, ponds, and waterway; rain gardens; and some pilot-scale vegetated roofs and porous paving. There are many examples of these practices on the Davis campus. One example is at Tercero student housing (dorms), where bioswales were used to create a pleasing landscape and manage storm water detention and filtering. The LEED Gold project won design awards in part for its storm water management measures.

Since the early 1990’s, the campus has employed various storm water controls to reduce pollutants from discharging into the campus storm water conveyance system.

The campus Storm Water Management Plan (SWMP) includes a number of construction and post-construction controls including permanent structural and non-structural Best Management Practices (BMPs) for storm water runoff to prevent and minimize water quality impacts from new development and significant redevelopment projects. A significant redevelopment project is one where the impervious area after construction is larger than the pre-construction impervious area.

The campus implements long-term post-construction BMPs using design measures and storm water controls to replicate the pre-project runoff water balance (defined as the amount of rainfall that ends up as runoff) for the smallest storm up to the 85th percentile storm event, or the smallest storm event that generates runoff, whichever is larger. Post-construction programs are most effective when they stress (i) low impact development (LID); (ii) source controls; and (iii) treatment controls.

The UC Davis campus continues to evaluate post-construction Best Management Practices (BMPs) requirements to reduce storm water runoff from campus new development and redevelopment projects. These post-construction BMPs are now being incorporated into the design phase process of campus construction projects.

UC Davis is covered by the NPDES General Permit for Storm Water Discharges from Small Municipal Separate Storm Sewer Systems (Phase II Small MS4 Permit). The Phase II Small MS4 General Permit requires the discharger to develop and implement best management practices through a coordinated storm water program with the goal of reducing the discharge of pollutants to the maximum extent practicable, which is the performance standard specified in Section 402(p) of the CWA. The Phase II Small MS4 Permit requires that jurisdictions covered by the permit to comply with best management practices (BMPs) to achieve compliance with minimum control measures (Education and Outreach, Public Involvement and Participation, Illicit Discharge Detection and Elimination, Construction Site Storm Water Runoff Control, Pollution Prevention/Good Housekeeping, and Post-Construction Storm water Management. UC Davis has a comprehensive storm water management program, which is continuously updated to meet the MS4 permit requirements.

Storm water management on campus is overseen by the Department of Environmental Health and Safety (EHS). EHS offers assistance and tools to prevent illicit discharges, control construction and post-construction storm water management, and ensures programs for storm water control are effectively achieving objectives and standards. The water quality program regulates storm water from municipal discharges through the MS4 permit system, described above, and regulates construction through both the MS4 permit and the General Construction Permit. EHS staff are available to provide assistance to developers. Section 01.57.23 Storm water Pollution Prevention of the UC Davis Campus Design Guide provides regulations and standards for the protection of receiving water from contamination by storm water discharges related to construction. The Campus Standards and Design Guide articulates the requirements of applicable laws relating to the discharge of storm water to assist developers and contractors in executing their projects which included the requirement to incorporate green infrastructure and Low Impact Design features.

The campus has a Storm Water Master Plan. In addition, the campus Long Range Development Plan Environmental Impact Report specifies mitigation measures regarding storm water management. Finally, the campus has managed storm water through a major on-campus detention waterway.

Relevant websites:
https://dcm.ucdavis.edu/campus-design-guide
https://safetyservices.ucdavis.edu/article/water-quality-program
https://environmentalplanning.ucdavis.edu/2018-lrdp-eir
https://campusplanning.ucdavis.edu/physical-design-framework

Examples of LID BMPs used on campus to support rain water management:
 Rain water harvesting - The Winery, Brewery and Food Science Teaching Laboratory harvests rainwater, as does the just completed Jess Jackson Sustainable Winery Building, which is seeking Living Building Challenge certification.
 Green roofs - The Segundo Services Center and the Student Health and Wellness Center both have roof sections that are vegetated. These are visible from other floors to also provide an educational opportunity.
 Porous paving - Porous paving is used in a variety of settings, including under bike parking.
 Rain gardens - The campus uses "rain gardens" or vegetated areas that slow and allow percolation of rain water. Examples of these can be found at King Hall School of Law and Valley Hall.
 Retention & detention ponds - The Arboretum Waterway serves as a nearly 2-mile long retention/detention pond for storm water and run off.
 Bioswales - The campus has numerous vegetated swales, including a very large swale at the Hopkins Service Center, which allowed the campus to avoid up-sizing the storm drain system.

Vindyani Jayasinghe, a visiting Humphrey Fellow with the Office of Sustainability, assisted in compiling this credit response.