USGS Banner
WATER RESOURCES RESEARCH GRANT PROPOSAL

TITLE: Mitigation of urban storm water discharges to City Park Lake through integrated passive adsorptive-filtration

FOCUS CATEGORIES: Nonpoint Pollution (NPP), Treatment (TRT), Toxic Substances (TS)

KEYWORDS: Storm water, Adsorption, Filtration, Heavy Metals, Urban Drainage, Breakthrough DURATION: Project start date: 1 April 1999 and Project end date: 28 February 2000

FEDERAL FUNDS REQUESTED: $18,375

NON-FEDERAL (MATCHING) FUNDS PLEDGED: $36,771

PRINCIPAL INVESTGATORS Dr. John J. Sansalone, P.E.1 Dr. Frank K. Cartledge Dr. Kelly A. Rusch, P.E.

CONGRESSIONAL DISTRICT: Louisiana State University is located in the 6th Congressional District.

STATEMENT OF CRITICAL REGIONAL WATER PROBLEMS

Storm water runoff from NPDES Phase II urban areas transports significant loads of heavy metals, a wide gradation of particulate matter, dissolved solids and organic compounds to receiving waters (Sansalone et al., 1998). Heavy metals are not degraded in the environment and constitute an important class of potentially acute and chronic toxic contaminants generated mainly through modern urban transportation activities and abrasion of infrastructure. In urban storm water levels of Zn, Cu, Cd, Pb, Cr and Ni are significantly above ambient background levels, and for many urban areas, Zn, Cu, and Cd often exceed USEPA and State EPA surface water discharge criteria on an event basis (Sansalone et al, 1997). Annual heavy metal, total suspended solids (TSS), chemical oxygen demand (COD) loadings and storm water flows from urban pavement equal or exceed annual loadings and flows from untreated domestic and industrial wastewater combined, for urban areas (Sansalone et al., 1998). With regard to storm water regulation and treatment, there are 32 NPDES Phase II urban areas and an additional 14 "incorporated places" that come under the proposed Phase II regulations in Louisiana. Both Phase II regulations and third-party lawsuits from organizations such as the National Resources Defense Council have helped spur a focus by municipalities, State DOTs and federal agencies such as FHWA on the treatment methodology for roadway stormwater.

Treatment of urban roadway storm water continues to pose unique challenges due to unsteady nature of processes including rainfall-runoff, mobilization and transport of heavy metal as well as other constituent loads. Additionally, kinetics of heavy metal partitioning as a function of pH, residence time and particulate matter characteristics can have a profound effect on the selection and effectiveness of treatment systems. Treatment systems for the clarification of runoff have included sedimentation (detention/retention) basins, constructed wetlands, vegetated filter strips and infiltration systems such as porous pavement and infiltration trenches. While many of these have varying degrees of viability, none are applicable for the many sections of elevated roadways in Louisiana. The State of Louisiana has more miles of elevated roadways than any other state in the USA. Storm water effluent from these roadways is currently discharged untreated into receiving waters and surficial soils. A novel passive treatment system, a pavement effluent reactor (PER), synthesizes the treatment mechanisms of both dissolved heavy metal adsorption and particulate-bound heavy metal filtration. The PER is a tubular packed-bed reactor designed to accept storm water runoff flows that currently discharge directly from elevated roadway scuppers and drainage boxes directly into receiving waters. The two-stage PER consists of an upper layer of porous cementitious aggregate and a bed of oxide-coated sand to promote sorption of dissolved heavy metals and filtration of particulate-bound heavy metals. The PER is mounted directly onto the outlet end of the drainage appurtenances, typically 150-mm to 200-mm diameter downspout or drainage pipes.

STATEMENT OF RESULTS AND BENEFITS

From preliminary research and experience in the field of nonpoint pollution treatment, the investigators have not identified any rigorous scientific attempts to integrate passive treatment into existing elevated roadway infrastructure and evaluate the effectiveness of such treatment. As a result the objectives of this proposed research are fourfold. The primary objective is to demonstrate the effectiveness of a PER on heavy metal mitigation for elevated roadway sections in Louisiana. One typical local example for the Southeastern region of Louisiana is the I-10 elevated roadway section over City Park Lake in urban Baton Rouge. Storm water effluent from this heavily travelled elevated roadway is discharged directly into City Park Lake has not been quantified but is considered a major source of heavy metal loading to City Park Lake (Malone et al. 1988). The westbound elevated roadway section and a portion of the storm water effluent from that section over the lake will serve as the experimental site. The second objective will also include an evaluation of the potential for clogging of the PER including the development of any required maintenance and backwashing procedures. The third objective is to investigate PER removal mechanisms as a function of storm water residence time/flow and heavy metal partitioning. The final objective is to provide a database for PER performance as a new treatment technology and evaluate PER economic benefits as a multi-purpose environmental infrastructure. Results and analysis will be fully documented in a final report and provided for peer-review through at least two manuscripts.

Note: This proposal for $18,375 forms an integral component of a 2-year comprehensive proposal. To facilitate this comprehensive proposal, funds and in-kind services have been solicited from a number of sponsors. The component funding and in-kind services are summarized as follows:

At this time, USEPA has approved their portion of the funding, LSU has committed to matching money for student support and matching time ($36,771). Mr. Jorge Ferrer, head of the Environmental Division of Department of Public Works has verbally committed to the analytic work and a support letter is attached from Louisiana Transportation Research Center.

NATURE, SCOPE AND OBJECTIVES

Storm water runoff from urban areas transports significant loads of heavy metals, a wide gradation of particulate matter, dissolved solids, organic compounds and inorganic constituents. Heavy metals are not degraded in the environment and constitute an important class of contaminants generated through modern urban activities and infrastructure. In urban areas one major source of heavy metals are traffic activities. In urban runoff discharges levels of Zn, Cu, Cd, Pb, Cr and Ni are significantly above ambient background levels, and for many urban areas, Zn, Cu, and Cd often exceed USEPA and State EPA surface water discharge criteria on an event basis.

Treatment of storm water continues to pose unique challenges due to unsteady nature of processes including rainfall-runoff, mobilization and transport of heavy metal as well as other constituent loads. Additionally, kinetics of heavy metal partitioning as a function of pH, residence time and particulate matter characteristics can have a profound effect on the selection and effectiveness of treatment systems. Treatment systems for the clarification of runoff have included sedimentation (detention/retention) basins, constructed wetlands, vegetated filter strips and infiltration systems such as porous pavement and infiltration trenches. A novel passive treatment system, a pavement effluent reactor (PER), synthesizes the treatment mechanisms of both dissolved heavy metal adsorption and particulate-bound heavy metal filtration. The PER is a tubular packed-bed reactor designed to accept storm water runoff flows that currently discharge directly from elevated roadway scuppers and drainage boxes directly into receiving waters. The two-stage PER consists of an upper layer of porous cementitious aggregate and a bed of oxide-coated sand to promote sorption of dissolved heavy metals and filtration of particulate-bound heavy metals. The PER is mounted directly onto the outlet end of the drainage appurtenances, typically 150-mm to 200-mm diameter downspout or drainage pipes.

Bench scale testing of various PER configurations and Fe-oxide sand media have demonstrated proof-of-concept (Sansalone, 1998). Bench scale testing using actual storm water and tubular packed-bed configurations indicate that the design life of a PER can exceed 5-years at a 50 percent heavy metal breakthrough level. Therefore this research approach intends to build on this development and proposes to construct, monitor and analyze a prototype PER (tubular, Fe-sand packed-bed configuration) subject to urban loading and conditions. The proposed PER demonstration experiments will be configured as two separate reactors, one with Fe-sand and the second reactor used as control, containing uncoated silica sand media. The diameter of each reactor will be approximately 50-cm and 150-cm in length based on a drainage area to each reactor is approximately 200 m2 of pavement. The rigid and porous surface of the PER strains incoming particulate matter while providing a hydraulic surface loading rate up to 100 L/m2-minute.

This project serves as a prototype field demonstration of economical multi-purpose urban storm water treatment. Construction, monitoring and sampling equipment procurement and installation will require 4 months. Data collection and analysis will continue for 18 months and the final report will be written during the final 2 months of the 24 month project. Each treatment system will be monitored. On-site climate monitoring will include rainfall, runoff, temperature, previous dry days, and traffic data will also be collected. Flow rates will be monitored and influent and effluent samples taken at regular intervals during at least 12 rainfall runoff event. Influent and effluent characteristics will also be analyzed. These include heavy metals, pH, redox, conductivity, TSS and TDS. The objectives of this proposed research are fourfold. The primary objective is to demonstrate the effectiveness of a PER on heavy metal mitigation for elevated roadway sections in Louisiana. The 2nd objective will evaluate the maintenance and potential for clogging of the PER. The 3rd objective is to investigate PER removal mechanisms as a function of storm water residence time/flow and heavy metal partitioning. The final objective is to provide a database for PER performance as a new treatment technology and evaluate PER economic benefits as a multi-purpose environmental infrastructure.


U.S. Department of the Interior, U.S. Geological Survey
URL: http://water.usgs.gov/wrri/99projects/state/Louisiana2.html
Maintained by: John Schefter
Last Updated: Wednesday March 23, 2005 9:17 AM
Privacy Statement || Disclaimer
|| Accessibility