Some of the most complicated problems with storm water management are Combined Sewer Systems (CSSs). In the late 1800s and early 1900s many cities built CSSs, which at the time provided a contemporary solution for removing sewage and stormwater efficiently. In optimal conditions, the stormwater and sewage were combined and conveyed to a sewage treatment plant. But today, with population growth and development, when the system is overwhelmed by the volume, it diverts all flows (stormwater AND sewage) into nearby waterways, and sometimes backs it up into neighborhoods, threatening human health. The environmental impact is that marine life and surrounding habitats become significantly threatened. CSSs are expensive and complicated problems to address because they connect to each other from one municipality to another. Due to the inter-connected nature of sewer systems among neighboring communities, a downstream region's strategy for addressing its Combined Sewer Overflows (CSOs) is directly impacted by the amount of flows from their upstream neighbors.
In response to the Clean Water Act and the National CSO Policy, the NJ Department of Environmental Protection issued 25 individual NJPDES permits allowing these overflows for a limited amount of time while they strategize to reduce or eliminate CSO outfalls in the 21 municipalities in New Jersey with CSSs. To meet the requirements of the permits, CSO communities must reduce flooding, ensure proper operation, maintain and manage existing infrastructure, and provide opportunities for green infrastructure. Properly operated and maintained water infrastructure systems are important in protecting public health and the environment but also are beneficial to economic development. The permit process stresses the development of regional strategies to reduce the amount of storm water that flows into CSSs through the development and implementation of a Long Term Control Plan.
Conventional stormwater management techniques often include pipes, sewers and other structures often referred to as "gray infrastructure." One of the more common practices is known as off-line storage, where combined effluent is diverted to a tank, a basin, or a deep tunnel until either the rain event has subsided or a wastewater treatment plant has the capacity to treat the discharge.
Green infrastructure practices simulate natural hydrologic methods to reduce the quantity and rate of stormwater emissions to the CSS. Green infrastructure strategies can include rain gardens, bioswales, porous pavement, green roofs, infiltration planters, trees, and rainwater harvesting rain gardens. These small-scale green infrastructure strategies help to keep stormwater out of the CSS through infiltration, evapotranspiration, and rainwater harvesting. The capture and reuse of rainwater preserves the resource and keeps it out of the CSS during critical storm events. Larger scale management strategies include riparian buffers, flood plain preservation or restoration, open space, wetland and forest preservation and restoration, and large infiltration at the watershed level. Green infrastructure is also compatible with the principals of Low Impact Development, a land development policy that reproduces natural methods of managing stormwater as close to its source as possible.
The 21 New Jersey cities with CSSs are encouraged to include green infrastructure projects in their long-term control plans because they contribute to CSO control while providing multiple environmental, social, and economic benefits. In addition to alleviating flooding issues, green infrastructure can improve water and air quality and reduce energy use and urban heat island effects, create green jobs and improve quality of life. Larger scale green infrastructure strategies can also increase recreational and economic opportunities, improve wildlife habitat and biodiversity, and help mitigate flooding. In addition, redevelopment opportunities become more promising when infrastructure can handle the population intended to use it.
As community leaders become aware of additional funding sources available, such as the Water Bank, they can overcome some of the obstacles that have been impeding critical infrastructure repair. The Water Bank is a vanguard lending institution in the State, helping communities take advantage of available financial resources with low-interest and principal forgiveness loans. The Water Bank has dedicated $25 million to Principal Forgiveness Loans for Combined Sewer Overflow Abatement projects utilizing gray and green practices. The benefits of investing in water infrastructure include stimulating the economy and reducing environmental and health impacts, while enhancing communities and beautifying their neighborhoods.
Illustrations courtesy of the EPA.
For more information, contact the New Jersey Infrastructure Bank at (609) 219-8600.
3131 Princeton Pike, Building 4 Suite 216
Lawrenceville NJ, 08648 T. 609 219 8600