Separate Storm Sewer Research Articles

Source apportionment of pollutants and flows of combined sewer wastewater

To reduce the combined sewer overflows (CSOs) and improve surface water quality in the Greater Milwaukee area, construction of a 19.5-mile (31.4 km) inline storage system (ISS) was completed in 1994 to capture and convey sanitary sewage and stormwater for treatment. However, one to six overflows per year still occur. Chemical mass balance (CMB) and positive matrix factorization (PMF) modeling was done in order to find origins of flows and pollutants in CSOs. Based on overflow events from 2000 to 2006 (CMB) and 2004 to 2006 (PMF), we found that between 27% and 56% of the total overflow is from sanitary sewage and most of the remaining from stormwater with possible minor contribution (⩽8%) from groundwater. Most total suspended solids and metals (Cd, Cr, Cu, Pb, Ni, Hg, and Zn) are from stormwater, while sanitary sewage carries large contributions (⩾28%) of BOD 5, NH 3, and total phosphorus. The fraction of NH 3 is especially high, i.e., ⩾58%. Implications for a possible future sewer separation in combined sewer areas into separate sanitary and storm sewers are discussed.

Tmdl Development from the "Bottom Up" – Part IV: Connecting to Storm Water Management Programs

A challenge facing many local jurisdictions across the country is finding ways to connect Storm Water Management Programs (SWMPs) required by NPDES permits with TMDLs intended to address water quality problems. A “bottom up” approach towards TMDL development is one way to establish a meaningful, value-added framework which links water quality concerns to proposed solutions. Information on Best Management Practices (BMPs) related to both source control and delivery reduction methods can be incorporated into TMDL allocations. Management measure information considered in TMDL allocations can then complement benchmarks that guide implementation efforts. Basic hydrology presented in the form of duration curves supports a “bottom up” approach and offers opportunities for enhanced pollutant source targeting. Duration curves add value to the TMDL process by characterizing water quality concerns in terms of flow conditions, linking these concerns to key watershed processes, prioritizing source assessment efforts, and identifying potential solutions. Federal regulations identify a set of minimum control measures to be included in SWMPs for municipal separate storm sewer systems (MS4), which are intended to reduce pollutant loads to the “maximum extent practicable” (MEP) and often directly support or advance TMDL water quality objectives. A number of these control measures are typically most effective in achieving intended benefits under specific flow conditions, depending on watershed characteristics. For example, water quality concerns experienced during low flow conditions in urban watersheds might involve eliminating illicit connections under an MS4 storm water program. Similarly, sediment problems observed during mid-range and moist conditions might be best addressed through construction site BMPs. Finally, water quality concerns associated with stream bank erosion under high flow conditions might involve post development BMPs intended to address channel protection. The natural linkage between basic hydrology and storm water makes the duration curve framework a potentially useful tool in targeting appropriate BMPs and in guiding implementation of SWMPs. Because duration curves are also used to support TMDL development, the framework is wellsuited for connecting water quality-based control efforts with SWMPs.

Variation of microorganism concentrations in urban stormwater runoff with land use and seasons

Stormwater runoff samples were collected from outfalls draining small municipal separate storm sewer systems. The samples were collected from three different land use areas based on local designation (high-density residential, low-density residential and landscaped commercial). The concentrations of microorganisms in the stormwater runoff were found to be similar in magnitude to, but less variable than, those reported in the stormwater National Pollutant Discharge Elimination System (NPDES) database. Microorganism concentrations from high-density residential areas were higher than those associated with low-density residential and landscaped commercial areas. Since the outfalls were free of sanitary wastewater cross-connections, the major sources of microorganisms to the stormwater runoff were most likely from the feces of domestic animals and wildlife. Concentrations of microorganisms were significantly affected by the season during which the samples were collected. The lowest concentrations were observed during winter except for Staphylococcus aureus. The Pearson correlation coefficients among different indicators showed weak linear relationships and the relationships were statistically significant. However, the relationships between indicators and pathogens were poorly correlated and were not statistically significant, suggesting the use of indicators as evidence of the presence of pathogens is not appropriate. Further, the correlation between the concentration of the traditionally monitored indicators (total coliforms and fecal coliforms) and the suggested substitutes (enterococci and E. coli) is weak, but statistically significant, suggesting that historical time series will be only a qualitative indicator of impaired waters under the revised criteria for recreational water quality by the US EPA.

Collection and Examination of a Municipal Separate Storm Sewer System Database

The University of Alabama and the Center for Watershed Protection were awarded an EPA Office of Water 104(b)3 grant in 2001 to collect and evaluate stormwater …

CHEMICAL CONSTITUENTS IN STORM FLOW VS. DRY WEATHER DISCHARGES IN CALIFORNIA STORM WATER CONVEYANCES1

ABSTRACT: This research evaluated concentration data for selected water quality parameters in selected California urban separate storm sewer systems during storm event discharges and during dry weather conditions. We used existing monitoring data from multiple regulatory agencies and municipalities originally collected for compliance or local characterization, which allowed systematic assessment of seasonal patterns over a wide region. Long term mean concentration for most parameters in most streams was higher during storm discharges than during dry weather flows to at least 95 percent confidence in 20 of 45 comparative evaluations, and lower statistical confidence in 22 other comparisons. Some regional differences emerged: in four evaluated streams in the San Francisco Bay Area, total concentration of lead, copper and zinc were lower during dry weather than during storm flows to at least 99.9 percent confidence, with only one exception; while the other four evaluated California streams showed the same tendency, but to much lower statistical confidence.

SEDIMENT TRANSPORT IN SEWERS - A STEP TOWARDS THE DESIGN OF SEWERS TO CONTROL SEDIMENT PROBLEMS.

Keywords HERIOT WATT UNIVERSITY, ABERTAY UNIVERSITY, SHEFFIELD UNIVERSITY, NEWCASTLE UNIVERSITY, CONSTRUCTION IND SEDIMENTS, TRANSPORT, SEWERS, DESIGN, SEWERAGE, MINIMISATION, REDUCTION, SEDIMENTATION, PROCEDURE, METHODS, STANDARDISATION, CALIBRATION, RESISTANCE, LABORATORIES, DRAINAGE, IRRIGATION, HYDRAULICS, HYDRODYNAMICS, DRAINS, OVERLOADING, SOLIDS, DEPOSITS, COMBINED, OVERFLOWS, STANDARDS, BRITISH, SUSPENDED, BEDS, LOADS, CAPACITY, ENTRAINMENT, CONDUITS, BOUNDARIES, SHEAR, STRESS... Show All

WATER QUALITY CONCERNS AND REGULATORY CONTROLS FOR NONSTORM WATER DISCHARGES TO STORM DRAINS

ABSTRACT: Nonstorm water discharges to municipal separate storm sewer systems (MS4s) are notable for spatial and temporal variability in volume, pollutant type, pollutant concentration, and activity of origin. The objective of this paper was to determine whether current technical knowledge and existing U.S. policy support an improved regulatory approach. The proposed policy would use type of discharge as a regulatory basis, merging the concepts of allowability of de minimis discharges and type-based statewide consistent rules. Specific research objectives were to comprehensively identify discharge types, characterize their prevalence in California, analyze relevant local and regional regulatory guidelines, and systematically evaluate opinions of experts about potential water quality impacts. Results demonstrate nonstorm water discharges were widespread in at least one sector, industrial facilities subject to a state permit; one discharge for every four facilities was reported in 1995, even though the permit explicitly prohibits such discharges. Clear consensus exists for minimal water quality concern for some discharge types when considering both municipal guidelines and experts’ opinions. In particular, condensate from a wide range of equipment and discharges from fire fighting equipment testing were found to be of low concern. Discharge types with consensus high concern were largely limited to discharges prohibited under other regulations, such as wastewater and hazardous waste management controls. Some discharge types where no consensus was identified, such as landscape irrigation, nevertheless generated concern for water quality impacts and appear to be relatively widespread. Available information supports technical feasibility of the proposed policy because at least some discharge types show strong consensus for de minimis impacts among regulatory guidelines and opinions of technical experts.

An Evaluation of Bacterial Standards and Disinfection Practices Used for the Assessment and Treatment of Stormwater

Publisher Summary This chapter presents an evaluation study of bacterial standards and disinfection practices used for the assessment and treatment of stormwater. The Environment Protection Agency's (EPA's) current emphasis on water-use attainability and risk assessment warrants the reevaluation of existing disinfection requirements and bacteriological criteria. Water quality and disinfection criteria based on human disease contraction potentials of pathogenic microorganisms are needed for stormwater as well as combination with stormwater (CSO). The results of some epidemiological studies strongly suggest that total coliform (TC) or fecal coliform (FC) indicators cannot be used to assess accurately the pathogenicity of recreational waters receiving stormwater from uncontaminated separate storm sewers or surface water runoff. Carefully planned strategy should be adopted for storm sewers containing evidence of human-fecal contamination to indicate the presence of illicit or inappropriate cross-connections. In stormwater outfalls where cross-connections are too numerous or too costly to be corrected, it is advisable to deal with the separate storm sewer system as a combined sewer system.

Phosphorus Loading from Urban Stormwater Runoff as a Factor in Lake Eutrophication: I. Theoretical Considerations and Qualitative Aspects

AbstractA theoretical fractionation of urban runoff phosphorus (P) according to its chemical mobility and potential biological impact is presented and the P fractions feasible for routine analysis established. Urban runoff P from two separate storm sewer systems draining residential areas in the Lake Wingra basin (Madison, Wis.) was characterized in detail. Flow‐weighted mean concentrations of dissolved inorganic P (Pi) for individual runoff events ranged from 0.10 to 2.11 mg P/liter and generally comprized ≥ 79% of the total dissolved P (Pt), allowing optimization of routine P characterization by the determination of dissolved Pi (or dissolved Pt) and total P. Flow‐weighted mean concentrations of total particulate P (Pt) ranged from 0.14 to 2.37 mg P/liter. However, while the composition of the particulate Pt at the lower concentrations was widely variable, at the higher concentrations particulate Pt was constituted mainly of organic P (Po). Flow‐weighted mean concentrations of dissolved Pi were more consistently correlated at a significant level with particulate Pt and particulate Po than with particulate Pi. The higher concentrations of dissolved and particulate P were associated with leaf and elm fruit fall, in the fall and spring, respectively, and with longer dry periods immediately before runoff events. A significant proportion (35 to 50%) of the particulate Pt occurring during the first flush and high flow phases of runoff events would remain suspended in the lake photic zone for several days. The upper limit for potentially available P in urban runoff can be given by dissolved Pi (or dissolved Pt) plus 0.25 × particulate Pt, for the watersheds studied.

Model for Selection of Stormwater Control Alternatives

Abstract In urban centres, the degree of pollution from combined sewer overflows and stormwater runoff is becoming ever more noticeable and critical. Among the many stormwater management alternatives for combined sewer overflow abatement, remote monitoring/real-time control is emerging as a cost-effective method in large urban centres. Its advantage is that it does not require additional facilities, but uses the existing system more effectively. A general computer model is needed in the planning stage, which can estimate the overall performance of real-time control and other stormwater management alternatives, without employing expensive, single-event models like WREM. The well-established and most widely used initial planning model STORM is unable to provide an overall system description. Therefore, a new programme, named RAFFI, was devised which can be combined with STORM. The RAFFI is a simple model which provides hourly information on flows and pollutants (BOD and SS) diverted into receiving waters from various overflow points and treatment and by-pass operations at the plant. The model can simulate the overall behaviour of existing and proposed systems in multi-basin urban areas for single storms, or for many storms over a long period, such as one year. In-system storage can be simulated by assuming that the interceptor acts as a common reservoir which can store flows from all watersheds, while each trunk can store flows only from the watershed that it serves. Dynamic regulators can be simulated according to a built-in control strategy, which changes the flow capacity of diversion pipes and outfalls, based on plant, trunk and interceptor flow and storage values at each hour. Capacities for primary, secondary or by-pass operations at the plant can be varied during storms. Treatment of overflows at each outfall can also be simulated. The model is equally applicable to separate storm sewer systems. The objective was not to produce yet another new model, but to integrate programme RAFFI with STORM, in order to increase its capabilities in the initial planning stage. By using STORM-RAFFI, a decision-maker can estimate the overall performance of an existing system during wet