Sarah J. Meyland, MS, JD, Associate Professor

Department of Environmental Technology

New York Institute of Technology

Phone: (516) 686-7765; Fax: (516) 686-7919

Dr. Melinda Lalor and Dr. Robert Pitt

Department of Civil and Environmental Engineering

The University of Alabama at Birmingham

Targeted water quality monitoring helps develop a better understanding of ambient conditions and trends and helps guide regulatory responses to issues of public health protection and water resource uses. An EPA-sponsored project is studying separate sanitary sewer overflows (SSOs) to determine the types of changes in stream quality that occur during and after an overflow event. The discharges from SSOs can contain nutrient-rich sanitary wastewater, pathogens, toxic and hazardous chemicals and heavy metals. Many SSO discharges occur during wet weather events and their contribution to water quality has not been extensively documented. It may be difficult to distinguish water quality changes caused by SSOs using traditional parameters of water quality (such as DO, TSS, BOD₅, etc.) from the many other contributions, both point and nonpoint, that streams and larger drainage areas receive. However, pathogen loads and toxicants from SSOs may be very important in urban watershed quality. This is especially true when SSOs drain into recreational contact waters, environmentally sensitive areas, drinking water sources or economically important waters such as shell fishing beds. Sewers can be a significant source of disease-producing protozoa such as Cryptosporidium and Giardia, which may remain viable for extended periods in streams and the stream beds.

A multiyear project examining the environmental and ecological impacts and public health risk associated with SSOs will complete phase one in mid-1998. This paper will review the goals of this US-EPA-funded study, look at main issues of the investigation, describe how the study and its results will be presented using a GIS-based system to increase its user-friendliness and application to many interested stakeholders.

It has long been understood that sewage collection, treatment and safe disposal is an essential community service that protects public health and environmental quality, especially water resources. The Federal Clean Water Act (1972) established the regulatory basis for setting treated sewage effluent standards and regulating sewage discharges. The Clean Water Act also required that sewage treatment plant operators receive NPDES permits (National Pollutant Discharge Elimination System program) that authorize the effluent discharge and within which the discharge quality criteria are defined.

In the early-1990s, the U.S. Environmental Protection Agency turned its attention to other sewage-related discharges, such as Combined Sewer Overflows (CSOs) and Separate Sanitary Sewer Overflows (SSOs). In 1995, following on the heels of a control policy on CSOs (Federal Register, April 19, 1994)¹, EPA sought stakeholder-advise on policy considerations for controlling and eliminating SSOs. Whereas CSOs fall within various exceptions allowed for discharges at the sewage treatment plant ("upsets" and "by-pass") and thus can be covered by the discharge permit, SSOs occur within the sewage collection system itself. These discharges are generally related to collection system failures that are without permit authorizations and are thus illegal. It is estimated that there were nearly 20,000 municipal separate sanitary sewer systems in the United States as of 1996 serving 147 million people. By comparison, there are only approximately 1,100 combined sewer systems serving about 43 million people in the U.S.

As part of the policy-making process, EPA funded a research project (CX-824848)² in 1996 to help define environmental impacts and health-related risks that could be attributed to SSOs. This report is based on the Phase One work related to the project. It has been a collaborative effort between universities in New York (New York Institute of Technology) and Alabama (University of Alabama at Birmingham) and a New York environmental organization (Citizens Environmental Research Institute).

Sewage in typical municipal domestic waste collection systems carries a variety of constituents that can alter local environmental conditions as well as spread disease-causing agents such as bacteria, viruses and protozoa. Sewage may include untreated human and animal wastes, household chemicals, industrial chemicals, pesticides, oxygen-demanding pollutants, suspended solids, nutrients, toxicants, floatable matter, radioactive materials and pathogens. Separate sewage collection systems are not intended to convey a significant level of stormwater and are expected to deliver the sewage in tact to the sewage treatment plant for processing prior to discharge. However, as many municipalities know, a number of things can go wrong along the route of the sewer lines. Sewer lines can leak, break, or become clogged with grease and debris; pump stations can fail, or the lines can simply be overwhelmed with sewage normal flow or by sewage combined with extraneous water from storms or other inflow, thus exceeding the conveyance capacity of the pipes. When the sewer lines are overwhelmed or blocked, the sewage backs up and overflows at the point of least resistence, which could be a building basement, a manhole cover, pump station or break in the line. The overflowing raw sewage from the collection system is known as a sewer system overflow. The overflow may be in an isolated location where it goes undetected for a long period or it may occur in a spot where it offers the potential for considerable human contact such as a street or residential basement or drinking water supply.

The unpredictable and random nature of SSOs, in part, makes them very hard to monitor and study. Unlike a CSO, which often occurs at a pre-designed location in the system, an SSO can happen almost anywhere along the sewer route. Many more SSOs occur during wet weather conditions than dry and the quality of the discharge can be very different between wet and dry overflows as well as over the period of a wet weather event. Historically, most SSOs have gone unreported or under-reported. Some of the most egregious overflow conditions have resulted in EPA enforcement actions, costing local communities millions of dollars to redesign, rebuild and/or tighten their collection systems. Perhaps more importantly, SSO have been specifically implicated in several locations where public health was directly affected. For example, in 1990 in Cabool, Missouri, SSOs leaked into nearby water lines, contaminating the drinking water with a pathogenic strain of E. coli. Four people died and about 250 were sickened. (EPA, Sanitary Sewer Overflows, 1996)³

A point that adds further importance to the concern over SSOs is the mounting evidence that sewage discharges in general contribute to a growing list of environmental warning signals such as the re-emergence of certain diseases, nutrient loading to the world’s water resources, hazardous algal blooms (HABs) such as Pfiesteria, human illness from water-borne exposure, endocrine-disrupting chemical exposures and changes in bio-diversity and ecosystem health.

Regulatory agencies and water resource managers have noted that surface water quality tends to decline following a storm event. This understanding is limited, however, by the use of a limited set of water quality characteristics (pH, BOD₅, DO, TTS and Coliform counts) in regulatory programs that do not fully portray the levels and types of contaminants that are added to the nation’s waters and sedimentary materials. Policy makers now seek to identify more clearly the contribution that each of many components adds to the overall water quality picture, especially at the local level. The purpose of this SSO research project was to provide guidance in assessing the health risk and environmental impacts related to SSO events.

The SSO research project had multiple aspects that were all intended to culminate in the development of a protocol or evaluative framework that sewage system operators and the interested public could use to gauge the potential impacts and risks of SSO events. Its tasks included:

SSO Discharges in a Typical River System: The Cahaba River

The area of Birmingham, Alabama (including Jefferson County, AL), has a history of SSO problems and impacts. At least two river systems (the Cahaba and the Black Warrior) run through the county. The Cahaba River in particular has been the subject of intense scrutiny and enforcement activity by the U.S. EPA and local citizens organizations. Researchers at the University of Alabama at Birmingham carried out a substantial portion of the project, building upon extensive work on storm water impacts to urban watersheds including the Cahaba River.

The Cahaba River runs for 190 miles, from the hills northeast of Birmingham to the Alabama River to the south, near Selma, Alabama. It is typical of many rivers across the U.S. that drain substantial land areas and which change in character and use from one portion of their watershed to another. The Cahaba River, for instance, drains 1,870 square miles in eight (8) counties. Nearly 800,000 people live within its watershed.

In the Birmingham area, the average daily discharge into the Cahaba River is 26 million gallons of sewage effluent from 24 municipal and 16 private sewage treatment plants. More than 100 industries also have over 176 outfall points into the Cahaba River or its tributaries. An average of 40 million gallons per day of treated sewage is released to the river in total. The river also receives high volumes of poorly or untreated sewage as well. From January through March of 1995, for instance, Jefferson County released 271 million gallons of wastewater that did not receive at least secondary level treatment. During the summer, parts of the river flow near Birmingham are nearly 100 treated sewage. (Bolton, The Birmingham News, May 5, 1996)⁴

Equally important, the river is a drinking water source and a recreational area. An average of 57 million gallons of water per day is withdrawn from the system for drinking water, supplying about 0.5 million people.

The Study Issues and Monitoring Locations:

Phase One of the SSO Study was designed to identify the main environmental issues, undertake preliminary field monitoring and equipment testing, and provide a literature review of research relevant to SSO discharges. During this phase, the project addresses the key physical and chemical processes affecting the fate and transport of toxicants and pathogens released by SSOs. The processes identified as most important were:

• Dilution and transport of toxicants and pathogens in the water column
• Deposition of settables
• Resuspension or scour of settable constituents
• Chemical exchange or dilution between the water column and sediment pore water

To test the impact that these processes have on discharges from SSOs, two urban streams were identified for study within the Birmingham area: 5-Mile Creek, a tributary to the Cahaba River in northern Birmingham, and a creek in Homewood, a suburb in southern Birmingham, which empties into Shades Creek and on into the Cahaba River. Each stream has an SSO discharge point.

The 5-Mile Creek site covers a 3-mile reach with 10 sampling points and has a continuous SSO discharge, which runs overland for 300 feet before reaching the creek. The overland flow was also studied. The Homewood study site covers a 2.5-mile reach with 10 sampling points. For each waterbody, upstream, midstream and downstream locations for sampling were established.

In-stream water quality parameters were also monitored. A review of the literature was conducted that characterized the constituents commonly present in municipal sewage. The following list was chosen for use in the impact studies (wet and dry weather conditions) of SSO discharges.

• Turbidity
• Conductivity
• pH
• Total Chlorine
• Fluoride
• Phosphorus
• Nitrate
• Ammonia
• Potassium
• Detergents
• E. coli
• Enterococci

In addition to the water quality parameters, specific pathogens were of interest:

• Protozoa: Giardia lamblia and Cryptosporidium parvum
• Bacteria: Pseudomonas Aeruginosa, Fecal Streptococcus, Fecal/Total Coliform

These pathogens have been implicated in health risks from exposure via consumption and recreational waters exposure such as bathing beaches.

A series of tests were performed by the Alabama researchers to investigate the presence and fate of the pathogens. In-Situ Pathogen Die-Off studies using standard methods were performed where protected containers of sample pathogens were placed in the stream and then sampled 6 times over a 21-day period. Most of the pathogens showed continued viability in the streams over the length of the study time. Modification of the current methods for the identification of Giardia and Cryptosporidium was also undertaken.

Another study was conducted that examined the length of time needed by bacteria to acclimate to additional materials present in sewage discharges under stream conditions and to measure the photosynthesis and respiration (P/R) rates for various mixtures of sewage and stream water. Previous studies had shown that traditional BOD₅ results may be inaccurate due to the need of bacteria to acclimate to the new mixtures of sewage and receiving waters.

YSI 6000 Continuously Monitoring Water Quality Sondes were deployed in the study area at 5-Mile Creek (2 upstream and 2 downstream from the SSO discharge) and the following water quality parameters were monitored:

• Dissolved Oxygen
• Oxidation Reduction Potential (ORP)
• Conductivity
• Turbidity
• Depth
• Temperature
• pH

The equipment was tested in unattended conditions for 2-week periods where it collected data at 15 minute intervals. This information was used in the P/R rate studies as well as storm even tracking. The equipment operated well. The obvious value of the continuous monitoring is that it develops a more comprehensive picture of water quality under many weather conditions.

Pollutants from SSOs enter the water column of the stream and also invade the water held in the interstitial spaces of the sedimentary material on the stream bed. Of the five processes that affect pollutant exchange between in-stream water and the interstitial water, those that promote turbulent mixing are the most important. Sediment size is a controlling feature. Nearly 60 sediment samples were tested to characterize the material and search for pollutants. Among the chemical compounds detected were sulfur compounds, phenols, phthalate esters and petroleum compounds, PAHs and steroids.

The extensive field and laboratory work is essential to the application of computer modeling of environmental and health risk. The results of the field monitoring will be used to calibrate the predictive model or models that are selected as most suitable for the project. Over 40 predictive models were reviewed by NYIT for use in the project. From the initial screening 12 models were selected for a detailed analysis of model parameters, assumptions, default values and sensitivity.

During Phase Two of the Project, the model/s will be calibrated and predictive evaluations run under a range of SSO event conditions.

While the field and laboratory work was undertaken in Alabama, a GIS application was created at NYIT that will be used to track the results of the project and provide a generic tool for applying the methodology and Phase Two results of the project. The US-EPA BASINS program in conjunction with ArcView 2.1 was used as the foundation of the GIS. To create a base map, USGS digital quad maps (1:24,000) with geo-referenced features locating the study sites were obtained commercially. Data bases from BASINS were selected to demonstrate how localities could use some initially available environmental monitoring data to supplement original data collection. The level of detail available in the BASINS data may not be fine enough for some areas of the country.