United States Department of Transportation
i
Hydrodynamic Separators As Stormwater Best Management Practices
-
2005-04-01
[PDF-8.82 MB]
Details:
-
Creators:
-
Corporate Creators:
-
Corporate Contributors:
-
Subject/TRT Terms:
-
Publication/ Report Number:
-
Resource Type:
-
Geographical Coverage:
-
TRIS Online Accession Number:01001263
-
Edition:Final Report
-
Corporate Publisher:
-
Abstract:The use of hydrodynamic separators in the treatment of stormwater runoff for Utah Department of Transportation (UDOT) basins was evaluated. This evaluation included the following tasks: 1) identify potential stormwater pollutants of concern in transportation corridors, 2) identify documented stormwater pollutant load estimation methods, 3) prepare a listing of available proprietary treatment Best Management Practices (BMPs), 4) develop a selection methodology for water quality BMPs, and 5) prepare technical specifications for hydrodynamic separators. This project reviewed published literature and existing UDOT resources. Stormwater discharges contain constituents that can be characterized by land use activities and are largely dependent on climate patterns. Typical potential pollutants of concern for transportation use drainage basins consist of: sediment, floatables, metals and petroleum hydrocarbons. Specific land use analysis and evaluation of potential pollutants of concern are required prior to the selection and design of treatment BMPs. Total suspended solids (TSS) may be a target constituent of treatment BMPs, based on Salt Lake County's Event Mean Concentration (EMC) measurements; the average concentration of TSS in urban stormwater in Salt Lake County is 116 mg/l whereas oil and grease concentrations are typically in the range of 5-10 mg/l. Hydrodynamic separators cannot treat oil and grease in stormwater runoff to lower levels. Methods to estimate or predict pollutant loads are documented and recognized by many federal and state agencies. The U.S. Geological Survey and the Environmental Protection Agency both recognize quantitative analysis methods to estimate pollutant loads to receiving waters conveyed by stormwater runoff. Prediction of pollutant loads may be conducted to assist with the selection, operation and maintenance of stormwater treatment BMPs. These methods are highly sensitive to land use, percent impervious areas and precipitation events, and therefore produce a wide range of potential loading numbers. To remove sediment from stormwater discharges, hydrodynamic separators may be designed to treat small storm events or the first flush produced during larger storm events. A design water quality storm event of 0.5 in. of rainfall has been identified as design criteria to size the hydrodynamic separator. Other design criteria include sediment storage capacity of the device, head loss, sediment particle size and overall efficiency of the treatment measure. Flows exceeding the design event will need to be routed around, or bypass the treatment device. Specifications for hydrodynamic separators were developed for use by UDOT design engineers. In conclusion, oil water/hydrodynamic separators are not recommended for use in removing oil and grease in typical urban stormwater runoff. These systems may be considered for use in spill containment, removal of oil and grease from high-risk areas, or to assist with the removal of sediments in stormwater.
-
Format:
-
Funding:
-
Collection(s):
-
Main Document Checksum:
-
Download URL:
-
File Type:
