The Relationship Between Stormwater Management and Sewer Systems

April 2020 | PRIME

As the human race evolved into communities, the connection between their waste and their health became a great concern, particularly as populations grew exponentially. For this reason, societies began designing solutions to preserve the cleanliness of their water supply. Nature assisted in both the improvement of water supply and the disposal of waste through precipitation and surface water. But growing populations required systems to move both precipitation and waste away from populations. The most trusted solution has been to develop conduits. Sewers are conduits for the elimination of human waste materials from homes or businesses to wastewater treatment systems. Storm sewers are conduits for the elimination of stormwater. The distinction between the two has a rather murky past.

A Look Back
The history of sewers can be traced back to ancient times when the Romans, Macedonians, Persians and Greeks created systems to deliver water to people and convey waste away from their metropolises. Because civilizations depended on water, the earliest communities were built adjacent to major water systems for the purpose of providing drinking water. These early cultures relied upon that same system to dispose of their waste, assuming dilution would dissipate contaminants. As cultures moved closer together, this practice of running all waste downstream began to cause problems to downstream neighbors. It was not until the 1800s that the close relationship between water supply and water contamination was directly connected when cholera and typhoid epidemics brought to light the risks of waterborne pathogens. The spread of disease forced the world to develop solutions and understand this consumption/disposal relationship in order to protect the human race.

Building and maintaining infrastructure that addressed the separation of water and sewage and upgrading that infrastructure was an additional hurdle. It was still several decades before large cities began to develop infrastructure to separate the two systems; it took even longer to develop legislation to protect public water supplies and to separate drinking water from wastewater.

Communities like Worcester, Mass., began implementing the chemical treatment of sewage as early as 1890. However, the treatment was not universally applied throughout rural areas. As of 1945, it was estimated that over 3,500 communities in the U.S. were pumping 2.5 billion tons of raw sewage into public water every day.¹ National education programs for health along with successful improvements to sanitation and hygiene nearly eradicated waterborne diseases like typhoid and cholera from the U.S. The study of epidemiology and the establishment of the Communicable Disease Center (now the Centers for Disease Control and Prevention, or CDC) assisted to dramatically improve public health.² The average human lifespan in 1900 was 47 years; by 1950, it had increased to 67.³ Following waterborne illnesses, the most life-threatening agents were, and still are, cancer and heart disease.⁴

The Clean Water Act
The Clean Water Act (CWA) of 1972 resulted from an infamous fire on the Cuyahoga River in 1969. This first iteration of the CWA addressed industrial waste (a potential carcinogen) and sometimes flammable materials. Iterations began to investigate how other forms of pollution were reaching water supplies. In order to further protect the public, the CWA developed the National Pollutant Discharge Elimination System (NPDES), which addressed additional point source⁵ pollution strategies. According to the U.S. EPA, “An NPDES permit is typically a license for a facility to discharge a specified amount of a pollutant into a receiving water under certain conditions. Permits may also authorize facilities to process, incinerate, landfill, or beneficially use sewage sludge. The two basic types of NPDES permits issued are individual and general permits.”
A study conducted in 2018 concluded that the CWA successfully improved water quality, home values and public health,⁶ and that the cost to implement the CWA does not outweigh the benefits (Keiser, Shapiro 2018).

Shortly after the CWA was created, the impacts of stormwater were discovered. Stormwater quickly flows over impermeable surfaces, picks up many small pollutants and ultimately deposits them in a slow-moving water body. Typically, these pollutants tend to accumulate in semi-enclosed areas such as estuaries; bays and gulfs, where their effects become particularly obvious when the continued poor water quality impacts tourism; fish populations; and the degradation of hunting grounds. When algal populations began to degrade and smell, or when swimmers emerged from oceans with a film on their skin or soot on their feet from beaches, communities searched for the source.

The first solution to address stormwater was the creation of large channels to convey stormwater away from residential and business areas. Most major cities in the U.S. expanded upon earlier systems by increasing the size and lining of the old brick channels with concrete liners connected into long series. This solution only made the problem worse and territorial waters, such as the Gulf of Mexico and the Chesapeake Bay, were dramatically impacted. Economics came into play when crustaceans and the industries that depended upon their harvesting saw dramatic changes in the availability and quality of this food source. Blue crab populations alone in the Chesapeake Bay dropped from 791 million in 1990 to 260 million in 2008.⁷

In the early 1990s, pollution became redefined to include non-point source pollution (NPS). NPS⁸ originated from roadways, rooftops, parking lots and other paved surfaces. During the housing boom of the 1990s, the world was forced to address how to supply additional clean drinking water, dispose of additional wastewater and address increased stormwater from more impermeable surface runoff. The CWA responded with additional regulations and ultimately municipal stormwater sewer system (MS4) regulations were developed. The EPA defines an MS4 as “a conveyance or system of conveyances that is: owned by a state, city, town, village, or other public entity that discharges to water of the U.S. designed or used to collect or convey stormwater. They are not a combined sewer and they are not part of a sewage treatment plant or publicly owned treatment works.”⁹ These systems are intended to be and are typically separate from sanitary sewer systems.

The connection between sanitary sewer systems and storm drain systems occurs when it rains. In heavily populated regions and in areas where infrastructure is vulnerable, this is particularly true. The Riverkeeper organization in New York City states, “Sewer overflows are never farther away than the nearest storm cloud.” Rainwater inundation frequently overlaps sewer systems as soon as it reaches 0.4 inches. During larger rain events, treatment plants, in-home sewers and septic fields are impacted, while exposed sewer manholes, eroded piping and weak infrastructure are all at risk of failure. In New York City, it is estimated that “27 billion gallons of raw sewage and polluted stormwater discharge into New York Harbor alone each year and the average weekly polluted discharge is about 500 million gallons.”¹⁰ The 329.45 million people in New York combined with higher intensity rainfall and increasing temperatures (which allow algae growth to accelerate) associated with climate change means potential exposure and increased health risks. Pollution around cities built along waterways receive the upstream pollution more rapidly, including surges of accelerated flows.

Population, poorly maintained infrastructure and removal of wetlands and storm sewers are bringing back the risk of waterborne diseases. “During high rainfall periods, the sewer can become overloaded and overflowed, bypassing treatment. As it discharges to a nearby stream or river, untreated sewage enters the river system. Runoff from roads, parking lots, and yards can carry animal waste to streams through storm sewers. High amounts of sediment are often related to high concentrations of pathogenic bacteria, which can attach to sediment particles. Fast-running water can carry more sediment, so higher levels of bacteria could occur during high runoff events.”¹¹ This was demonstrated in a recent study, which concluded, “Stormwater runoff is the fastest-growing source of pollution to the Chesapeake Bay. According to data from the Chesapeake Bay Program’s Watershed Model, stormwater contributed 16 percent of nitrogen loads, 18 percent of phosphorus loads and 24 percent of sediment loads to the Bay in 2015.”¹²

MS4 Programs

MS4 programs are a critical component of increased water protections. Encouraging best management practices (BMPs) in our private and public lives will encourage others to follow our lead. Peer review and information sharing will help us acknowledge and learn from mistakes and inspire better practices from our work community.

Additional practices should also be reinforced, such as implementing these six minimum control measures:

  1. Public education and outreach—caring about our water programs
  2. Public involvement—placing signage on sewer covers, public reporting of Sanitary Sewer Overflows (SSO)
  3. Illicit discharge detection and elimination—preparing, reporting and correcting
  4. Construction site runoff—protecting, inspecting, correcting our ESC plans
  5. Post-construction runoff—covering exposed areas
  6. Good housekeeping—taking care of job sites between rain events, cleaning inlets, conducting frequent inspections

Other practices could include:

  • Bioretention facilities—fixing any non-working errors
  • Engineering solutions that incorporate green infrastructure to complement gray infrastructure

More work is necessary to protect our water supplies, and this work starts with each one of us. The Chesapeake Bay Foundation has supplemental ideas: “To lessen the impacts of stormwater runoff, consider reducing the amount of precipitation that runs off of your property. Install a green roof, rain garden or rain barrel to capture and absorb rainfall; use porous surfaces like gravel or pavers in place of asphalt or concrete; and redirect home downspouts onto grass or gravel rather than paved driveways or sidewalks.” Like most things in life, if we work together, we can make improvements. The more people understand the smaller impacts, the greater the overall benefits. While the human race has evolved significantly, our ability to manage our waste and runoff needs to be considered for the health of us all.

About the Expert
Nancy Schumm, CPESC, PWS, CMS4S is the water resources environmental manager at PRIME AE Group Inc. in Baltimore. She is an award-winning author of two books on natural areas and plant history, and three books on regional history. Schumm has been lecturing and presenting professional papers on historical topics nationally and internationally since 1997, including a program on the history of the Clean Water Act. Her work has been featured in magazines, newspapers and on the Oprah Winfrey Show.

¹ Barry, Frank J. 1969-70. “The Evolution of Enforcement Provisions of the Federal Water Pollution Control Act: A Study of the Difficulty in Developing Effective Legislation.” 68 Michigan Law Review 1103 ²
⁵ Point source is pollution that comes from an obvious point of origin.
⁶, David Keiser, Assistant Professor of Resource Economics University of Massachusetts, Joseph S. Shapiro, Associate Professor, Department of Agricultural and Resource Economics, University of California, Berkeley.
⁸ NPS is defined as pollutants from a variety of unidentified sources, versus a point source like a pipe
¹¹, Orman, PG.

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