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GeoInsighter Winter 2002 Newsletter 2003 - The Year of the Storm Water Return to the Newsletter Index The United States Environmental Protection Agency (USEPA) plans to invoke its Phase II rules regarding storm USEPA Phase II rules are designed to further control some of the significant non-point sources of storm water pollutants. Common pollutants include oil and grease from storage tanks and machinery; heavy metals from improperly disposed batteries, paints, and pesticides; nutrients from fertilizers; chemicals from cleaning products used to wash vehicles and equipment; and sediment from poorly vegetated or unstable soils common at construction sites. The National Pollutant Discharge Elimination System (NPDES) Phase II rules affecting Storm Water Pollution Prevention Plans (SWPPPs) will be in effect this March. With the Phase II rules change, no longer are operators of small construction sites that disturb a parcel of land ranging from 1 acre to 5 acres excluded from the requirements of a SWPPP. The Phase II rules also require municipalities operating a separate storm water conveyance system that were not previously covered by the Phase I rules to develop, implement, and enforce a storm water management program. Many cities and towns have anticipated these rule changes and have already begun implementing requirements to limit the discharge of storm water into often already overloaded municipal systems. Many developers will be left with the challenge of demonstrating to local Zoning Boards that storm water will be infiltrated on-site. In past practice, engineers and developers would often use a detention or infiltration basin as the means of solving this problem. But today’s developments are designed to maximize land use. A 25-year storm runoff volume can require the construction of a basin with a size that occupies a significant portion of the otherwise useable space at the proposed facility. To overcome this challenge, engineers have turned to subsurface water storage and infiltration system designs. This concept has been used for years, but usually in relatively specific applications. Today, with advancements in concrete, plastics, and geosynthetics, products exist that are specifically designed to capture, store, and infiltrate storm water underground in a controlled manner. Whether you have soils with a low permeability, small lot size, heavy traffic areas, or environmentally sensitive receptors nearby, many subsurface infiltration systems are available to effectively perform subsurface storm water storage and infiltration. Some of these structures include advanced treatment separators, flow distributors and equalizers, and infiltration pipes and chambers. Storm water is typically captured in a traditional manner using a series of catch basins, sedimentation traps, oil/water separators, piping, separator manholes, and where not released to a surface outlet, a subsurface infiltration system. The subsurface infiltration system is usually a specific designed storm event (i.e., 10 or 25 year) to calculate anticipated runoff volume, and the permeability of the subsurface infiltrating soils. Site requirements and restrictions are then matched with an appropriate distribution and infiltration system using substantial manufacturer’s performance data that is now available to engineers. Many products now on the market provide significant advantages over the traditional systems because of their combination of load-carrying capability, application-specific connections, lightweight durable construction, and ease of construction. When designed correctly, these advanced subsurface infiltration systems provide effective and economical solutions to the storm water challenges that government, state, and local agencies are requiring of new site developments. Many projects throughout New England are taking advantage of subsurface infiltration of storm water to achieve more rapid approval of site development plans and less significant long-term compliance requirements compared to surface water discharges. Michael J. Redding Return to the Newsletter
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water management for industrial and construction facilities this year. According to the USEPA, storm water from urban runoff is one of the leading causes of pollution in rivers and lakes. Development of residential, commercial, and industrial facilities reduces storm water infiltration, resulting in higher runoff to rivers and lakes. Subsequently, storm water that comes in contact with pollutant sources can transport pollutants to nearby rivers and lakes.