Sand Filters

Description
A sand filter is a device that uses sand or gravel to filter out, or strain, particles and particle-bound constituents found in stormwater. The primary treatment process is filtration. Common constituents that are removed include total suspended solids (TSS), total phosphorus, total and dissolved metals, microbiological constituents, and litter.

Experience
Caltrans Tahoe Basin Small-Scale Pilot Studies – Sand Filters
The Caltrans Tahoe Basin Stormwater Pilot Program consists of both small-scale and full-scale pilot studies. Small-scale sand filter columns were constructed and operated intermittently to treat discrete batches of stormwater collected from various runoff events. The primary objective of this study was to determine the expected performance of sand filters in removing turbidity and nutrients from Tahoe stormwater runoff. As well as determining the performance of different sand media (e.g., coarse, fine, and concrete), this study evaluated the effect of chemical addition and the hydraulic benefits of fabric prefiltration and graded media.

OWP Tasks
  • Assisted in Study Planning
  • Reviewed Experimental Designs and Methods
  • Provided Technical Assistance
  • Assessed Study Results
Report/Study Link: Caltrans Tahoe Basin Small-Scale Pilot Studies – Sand Filters
OWP Contacts: Dipen Patel | John Johnston
Caltrans BMP Retrofit Study
This study analyzed the costs and benefits of thirteen types of treatment BMPs designed to treat stormwater runoff from a variety of Caltrans facilities, including highways, park & ride lots, and maintenance stations. Construction costs, maintenance requirements, and stormwater quality data were collected and analyzed.

OWP Tasks
  • Assisted in Study Planning
  • Reviewed Design of BMP Retrofits
  • Reviewed Design of Monitoring Systems
  • Provided Monitoring Assistance
  • Reviewed Data Assessment and Reporting
Report/Study Link: Caltrans BMP Retrofit Study
OWP Contacts: Brian Currier
Caltrans District 12 State Route 73 Pilot Program – Sand Filters
The District 12 State Route 73 Pilot Program was a multi-year field study conducted in Orange County. The primary objective was to assess the effectiveness of twenty-four pilot Best Management Practices (BMPs) for treating stormwater runoff from freeways. Included in the program were two types of Austin sand filters: partial sedimentation design and full sedimentation design. For each filter type, influent and effluent water quality samples were collected and compared, and operation and maintenance activities were recorded to develop maintenance protocols. The collected data were also compared to other sand filter studies conducted by Caltrans.

OWP Tasks
  • Assisted in Study Planning
  • Reviewed Designs of Sand Filters
  • Provided Review of Installation/Construction Activities
  • Provided Monitoring Assistance
Report/Study Link: Caltrans District 12 State Route 73 Pilot Program – Sand Filters
OWP Contacts: David Alderete
Caltrans State Route 267 Filter Fabric Sand Trap Pilot Study
This study was conducted to test the effectiveness of an enhanced, two-stage treatment process in treating highway runoff. Two vault-type BMPs were installed along Highway 267 near Kings Beach, California. The treatment process consisted of settling followed by filtration through filter fabric. Monitoring was performed on the influent and effluent of the filters to determine their effectiveness in removing TSS and turbidity. After the study was completed, the sites were used as part of the Caltrans Small Footprint Media Filter Study.

OWP Tasks
  • Assisted in Study Planning
  • Assisted in BMP Design
  • Provided Review of Installation/Construction Activities
  • Provided Monitoring Assistance
Report/Study Link: Caltrans State Route 267 Filter Fabric Sand Trap Pilot Study
OWP Contacts: Scott Meyer | Dipen Patel