2009

Watershed Retrofit and Management Evaluation for Urban Stormwater Management Systems in North Carolina

Kathy DeBusk et al. — Fri, 08 Jan 2010 14:18:54 PST

In response to water quality concerns in the Jordan Lake Reservoir and state and federal mandates, several cities in North Carolina are being required for the first time to reduce nutrient loads in stormwater from previously developed lands; that is, install retrofits. It is anticipated that similar requirements will become necessary for other urban areas as North Carolina. The goal of this study is to evaluate the feasibility of alternative approaches to stormwater management for existing developments within North Carolina cities. Evaluated alternatives include retrofitting onsite best management practices, off-stream treatment along mainstems of the urban drainage network, stream restoration, and alteration of stream corridors as urban greenways, among others. Geographic coverage of the study includes seven cities of the WRRI Urban Water Consortium Stormwater Group. Stormwater drainage networks at the citywide/watershed scale will be related to existing land use, land use plans, and zoning classes. Feasibility of alternatives will be measured by the cost-effectiveness of alternative practices in reducing peak flows and pollutant loads (nutrients and sediment) and the potential for ecological restoration. Two spatial scales will be used for feasibility analysis: One will focus on tributary watersheds at a scale of 260-520 hectares (1-2mi2), and one watershed from each of the cities will be selected with priority given to watersheds draining to impaired water bodies. The feasibility of retrofitting onsite BMPs within these watersheds will be evaluated. The second scale will focus on mainstems of drainage networks in one selected watershed to determine the feasibility of using larger off-stream management practices and improving stream corridor management.

Agency Problems in Irrigation Water Transfer: Who Works for What?

John D. Wiener — Fri, 08 Jan 2010 14:18:53 PST

Integration of Education, Scholarship, and Service through Stormwater Management

Robert G. Traver et al. — Fri, 08 Jan 2010 14:18:53 PST

Impacts of Road Salt on Water Resources in the Chicago Region

Walton R. Kelly et al. — Fri, 08 Jan 2010 14:18:52 PST

Water Sustainability: Results of the Army Installation Water Study

Natalie R.D. Myers et al. — Fri, 08 Jan 2010 14:18:51 PST

Army installations, like many communities, are experiencing water shortages. The key to sustaining water supplies is great cooperation among regional governing bodies. Traditional approaches of local governments implementing water policy in isolation have not worked. This presentation illustrates how the Army is establishing methods to assess regional supply and demand vulnerabilities and achieve local supply targets.

The scope of work addresses regional water issues. The national watershed assessment characterizes the overall "health" of watersheds. This uses an indicator framework based on 27 water quality and quantity indicators. The result is a quick and effective tool to identify pressures and thus employ appropriate detailed analyses. The regional water budgets, estimate water demand on a watershed level. The regional water budget projects supply and demand thirty years into the future—allowing "what if" analyses to support development of strategies to meet conservation goals. For example, regions are able to quantify the impacts of particular polices on future water supplies.

Army installations operate similar to small communities or universities. They are a governing district with a mix of land uses, economies, and social structures. As such, each entity knows all too well how scarce water supplies can impact the ability to sustain the population, quality of life, and mission. Installations, communities, and universities can learn from one another. Following is a brief synopsis of the Army’s water supply assessment tools documented within ERDC/CERL Technical Report entitled "Army Installation Water Sustainability Assessment" and due for public release in September of 2009. The report will be made accessible through the World Wide Web (WWW) at URL: http://www.cecer.army.mil

Water Demand and Supply Outlook for Greater Chicago Area

Ben Dziegielewski — Fri, 08 Jan 2010 14:18:50 PST

Hydrologic and Hydraulic Modeling of the Tunnel and Reservoir Plan System in Northeastern Illinois

Arthur R. Schmidt et al. — Fri, 08 Jan 2010 14:18:48 PST

The Tunnel and Reservoir Plan (TARP) was adopted by the Metropolitan Sanitary District of Greater Chicago in 1972 to address combined sewer overflow (CSO) pollution and flooding problems in 970 km2 of the Chicago metropolitan area served by combined sewers. TARP consists of about 175 km of tunnels, three reservoirs, 256 drop shafts, and over 600 connecting structures, pumping stations, and other appurtenances for the capture and storage of CSOs and for conveying the stored CSOs to water reclamation plants for treatment. The TARP system is comprised of three independent systems: the Calumet system serving the south suburbs and a portion of the south side of Chicago, the Upper Des Plaines system serving the northwest suburbs, and the Mainstream/ Des Plaines system serving the remainder of Chicago and the north, west and southwest suburbs.

The Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) desires to develop new, updated and enhanced computer models to allow for simulation of the TARP systems. The new models will be used to optimize operation of the system as actually constructed, to determine constraints in the system, identify physical changes that may be needed to improve performance, and allow what-if analyses to be performed for potential storm scenarios and facility revisions. The modeling includes development of a Physical Inventory system, Hydraulic Modeling of the TARP systems, and Hydrologic Modeling of the TARP service areas. The Physical Inventory provides a digital description of the physical geometry of the TARP system and the related hydraulic performance of system components. Hydrologic Modeling uses data for each dropshafts service area to determine hydrographs describing the inflows to the TARP systems. A ma jor component of the Hydrologic Modeling is to develop tools and methods that allow robust simulation of the extreme heterogeneity of highly urbanized systems and that provide guidance for data compilation needed to improve the accuracy of such simulations. Hydraulic Modeling uses the information from the Physical Inventory and the Hydrologic Modeling to simulate hydraulic response of the TARP system to different inputs. The Hydraulic Modeling tools developed are capable of simulating the range of possible flows in the system, from gravity flows over a dry bed to mixed gravity/surcharged flows to shocks and hydraulic transients.

Survey of Stormwater BMP Maintenance Practices

Andrew J. Erickson et al. — Fri, 08 Jan 2010 11:59:35 PST

Many stormwater management manuals and guidance documents have stated the importance and estimated frequency of maintenance for stormwater best management practices (BMPs), but few have documented the actual frequency and intensity of maintenance required to maintain a desired level of performance and efficiency. Increased attention to mass balance, numerical goals, total maximum daily loads (TMDLs), and non-degradation requirements has created the need for more emphasis on BMP maintenance in order to meet permitting and reporting requirements. The purpose of this paper is to advance short and long-term maintenance considerations so as to develop more realistic maintenance plans. To do so, we conducted a national literature search for maintenance costs and developed, distributed, analyzed the results of a detailed municipal public works survey. The specific goals of the survey were to identify and inventory stormwater BMP O&M efforts and costs. Survey questionnaires were sent to 106 cities with 28 responses received. The survey related to the following topics: number of BMPs in the city, frequency of BMP inspections, average staff-hours spent per routine inspection/maintenance, complexity of BMP maintenance, most frequent causes of performance deterioration within BMPs, and cost of non-routine maintenance activities. The results of the survey revealed that most (89%) cities perform routine maintenance once per year or less. Staff-hours per year ranged from one to four hours for most stormwater BMPs and but were significantly more for rain gardens (one to sixteen hours per year) and wetlands (one to nine hours per year). The most common causes of performance deterioration were sediment buildup and litter/debris for most stormwater BMPs. Respondents indicated that the removal of accumulated sediment incurred the largest cost of all BMP maintenance activities.