- CDS® Hydrodynamic Separator
Since its establishment in 1891, Stanford University has continued a vision for land use and resource management initiated by founders Jane and Leland Stanford. The 8,180 acre campus on the foothills and plains toward the center of the San Francisco peninsula has maintained the character reflected in its original design and charter, as two-thirds of the campus remains open or lightly developed.
The campus boasts over 43,000 trees, including the redwood that is the college team mascot for Cardinal athletics. It also has 1.4 million square feet of shrubs consisting of 800 different plant species, 1.2 million square feet of lawn, 190,000 LF of additional ground cover, a golf course, three dams and lakes, and 16 fountains.
Stanford’s rich natural heritage must also blend in with 670 major campus buildings, accounting for 13.1 million square feet of educational space, as well as housing to accommodate nearly 20,000 students. This includes 46 miles of road, a 49-megawatt power plant, a central heating and cooling plant, a high-voltage distribution system, two water systems, 78 miles of water lines, and 2,300 automatic irrigation valves to help maintain this pristine merger of man and nature. Such an atmosphere creates great beauty, but also puts tremendous pressure on architects, developers and engineers who must perform under intense scrutiny. They can be challenged by mandates to minimize the required development footprint and maintain ecological integrity during growth, especially when dealing with stormwater runoff. “Stanford is divided into two watersheds. These are primarily Matadero and San Francisquito Creek, along with a couple of other small tributaries” says Karla Tompkins, a civil engineer with the utility division of Stanford. “The Matadero area has a grassy swale which was built to help channel runoff”
The San Francisquito area gets a lot of loading attention and concern, as it drains directly into San Francisco Bay. The University installed a CDS hydrodynamic separator from Contech to protect this watershed. The CDS unit captures sediment, the primary pollutant in stormwater runoff, oil and grease from vehicles, and 100% of the manmade trash. Trash has become a significant concern in San Francisco Bay and the streams feeding it, so the CDS system is helping Stanford do its part to reduce that concern. Tompkins said, “It is one of the largest such units I have ever seen designed or used in my long professional career” The University is regulated by the San Francisco Bay Regional Water Quality Control Board, and governed by Santa Clara County along with 13 local communities and agencies in the Santa Clara Valley Water District. The physical viability of a solution is as vital as its performance. Tompkins notes such campus additions as the Contech product line proved essential to handle the increased flow to San Francisquito Creek generated by the recent renovation to the campus football stadium. Stanford has to undergo re-development in order to expand the campus. Limited space is available; so many stormwater treatment systems cannot be used. “Footprint size as well as adaptability for the natural protection of the trees and other plants is essential due to the very limited space and the unique stormwater demands of Stanford” Adds Tompkins A project like the football stadium redesign required the addition of over 10,000 square feet of impervious area, which meant documentation for approvals and blanket permit application be submitted. These requirements were paramount in the re-design of the football stadium.
Santa Clara County significantly restricted the grading work contain numerous protected trees. Therefore removal of the trees to make the project intimate with the surroundings made thearound the stadium because the adjacent hill slopes for expansion was not considered. The ability CDS product even more desirable. “These worked well because the underground units required less Tompkins. “We simply did not have the space for large, space than aboveground solutions” says aboveground, grassy retention areas”
The campus does utilize natural best management practices (BMPs) like swales where feasible, usually in combination with manufactured elements like the CDS and pump stations in a treatment train. This management strategy was deemed to be the most suitable and cost effective solution considering the pollutants expected from this site, including sediment, hydrocarbons, trash and debris. “The large size of the CDS installation generated a significant excess capacity. This allowed Stanford to create a bank for stormwater treatment flow” “The project was able to handle the football stadium runoff as well as allow for significant future development in-fill projects within the campus” notes Tompkins. “The 48-in. pipes of the unit provide significant drainage and the availability for additional pipe and flow. It was a great investment” “We are definitely looking at more regional stormwater and other environmental facilities, as opposed to individual project units” says Tompkins. “We are also encouraging projects that mix vegetative solutions with products like CDS that provide quality engineered solutions” “This will allow us to be even more socially conscious, and to encourage design without demanding excess and valuable space” Such future efforts as stormwater filtration and trash/sediment removal will require easy- to-install, small footprint, large flow, and large capacity solutions. Stanford University’s motto is “The Wind of Freedom Blows” That freedom ensures a bright environmental future for the institution and its students; and also for its salamanders!
- CDS® Hydrodynamic Separator