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Combined Sewer Overflow And Stormwater Management

Combined sewer overflow, stormwater, and disinfection regulations have resulted in a variety of study projects for facilities in Illinois. The U.S. EPA SWMM Model has been used to model an entire sewer system of a community of 35,000 people. The model was then used to evaluate alternatives to reduce combined sewer overflows, and the most cost-effective method found. Stormwater regulations have also resulted in analysis of industrial and commercial pollutant loads and drainage patterns.

Huff & Huff has recently assisted four Illinois communities on wet weather issues. In one, a new combined sewer overflow was successfully permitted with a one million gallon wet weather holding tank that was developed based on three months of sewer monitoring. The holding tank will hold first flush, and upon completion of the long-term control plan (partial sewer separation), the tank will result in less than four overflows per year. Huff & Huff has prepared the Capacity Management Operations and Maintenance (CMOM) report for one community, is currently working on the CMOM for a second community, and is assisting another firm on.

Huff & Huff completed the value engineering for another community that resulted in re-negotiating an alternative approach with the Illinois EPA, and a four-year extension.

A stormwater study to determine "first flush" and the extent of CSO was completed for several communities. A two-month field study measuring CSO during storm events and evaluating sewer flushing as a Best Management Practice was conducted in one study. Computer analysis of historical data at the treatment plant has been utilized to check runoff coefficients measured during isolated storm events to annual averages. As part of a quality assurance project, an extensive CSO study for a large city was analyzed for compliance and cost-effectiveness.

Huff & Huff assisted in the development of a storm water program for construction activities for a large natural gas utility. Once developed, Huff & Huff was tasked with developing three training modules (storm water permitting/BMPs, wetlands, and wetland permitting), and subsequently conducting the training seminars for the utility designers, field crews, and supervisors, plus the utility's outside contractors.

Huff & Huff, Inc. (H&H) has been involved with several stormwater projects for industrial, municipal, and commercial sectors. H&H evaluated the tradeoffs between stormwater control measures and wet weather flows for a redevelopment project of a municipality on Restricted Status. The runoff rates and volumes for various storm intensities were estimated and compared to sewage flows of the project.

H&H has participated in the infiltration/inflow studies conducted by municipalities in the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) service area. Review of SSES reports by communities and assistance in the SWMM modeling of these data were responsibilities of Huff & Huff. Recently, the firm has been involved with modeling the water quality in one of the TARP reservoirs and the impact of the dewatering of the reservoir on the wastewater treatment plant.

Important research in developing “green” or sustainable solutions include the following: 1) The firm has designed the storm water sampling system for evaluating four alternative porous pavements; 2) Storm water quality from various media plots on a “green” roof was monitored by the firm; 3) Bioswales to treat highway runoff from six mile of roadway were conceptually prepared; 4) Infiltration as a BMP was evaluated for a City of Chicago roadway in a former manufacturing site.

Non-point source contribution of sediment during storm events was investigated for a small stream in western Illinois. By measuring bank erosion, daily sediment loads at various points along the stream, and bottom sediment accumulation, the relative contributions of agricultural runoff, urban runoff, and stream erosion were determined.

Stormwater Pollution Prevention Plans have been completed for facilities located in six states. Permit applications and stormwater management practices have been reviewed for plant implementation.