|
|
Technical Papers
Sustained growth has allowed Tighe & Bond to attract the most talented professionals in the field, individuals that are committed to staying abreast of industry improvements and cutting-edge technology. As a result we have compiled a variety of technical papers authored by our staff which promote new ideas, approaches, and best practices. Come back often to view the abstracts or obtain copies of our most recent publications.
|
| | | Author(s): Peter J. Grabowski, P.E., David E. Pinsky, P.E., Gary M. Huntley, Stephen K. Rupar, P.E. | | Publication(s): Presentation at New England Water Works Association, Spring 2000 Joint Regional Operations Conference and Exhibition, Worcester, Massachusetts, April 12, 2000 | | [View Abstract] [Request Paper] | | The South Central Connecticut Regional Water Authority (Authority), one of the largest utilities in CT, owns and operates five wellfield treatment facilities and three surface water treatment plants in southern Connecticut. At all of the wellfields, chemical treatment currently consists of fluoridation, disinfection, and corrosion control. The adequacy of the existing chemical treatment systems relative to Authority, Ten State, CT Department of Public Health, and other applicable standards was evaluated, and numerous system upgrades were implemented. In addition, improvements at the wellfields were needed to meet the same performance and reliability standards as the utility's surface water treatment facilities. This paper also includes a chemical feed system guidelines checklist to assist operations staff at other water facilities in identifying potential deficiencies in chemical feed systems. | | | | | |
| | | Author(s): David J. Partridge, P.E., Michael R. Parsons, P.E., Stanley W. Kulig, P.E. | | Publication(s): Proceedings from the Water Environment Federation-Wet Weather Conference, May 2000 | | [View Abstract] [Request Paper] | | Faced with a potential $200 million program cost to abate the impacts of combined sewer overflows, the City of Chicopee, Massachusetts (population 58,000) embarked on an innovative program to reduce the extent of the problem and create a new local source of revenue, before implementation of conventional abatement measures. The program has been extremely successful in educating the City and its consultants on the relationship between land use, soil characteristics, and stormwater runoff. It also provided the City with technical information to support the establishment of a new stormwater management fee to fund stormwater and combined sewer overflow projects.
The City of Chicopee is sewered by a collection system that consists of more than 200 miles of both combined and separated sewers. During precipitation events, the capacity of the City’s collection system and the wastewater treatment plant (WWTP) is often exceeded, thus resulting in up to 30 combined sewer overflows (CSOs) to the Chicopee River and Connecticut River.
The City has been under an Administrative Order from the U.S. Environmental Protection Agency since 1995 to mitigate these CSO discharges. As part of the Administrative Order, the City elected to prepare a Stormwater Benefits Analysis to estimate the amount of runoff entering the combined system and evaluate means of reducing the amount in order to reduce or possibly eliminate CSOs.
The City recognized that privately owned properties are a major source of stormwater runoff and reducing runoff from these sources may provide significant benefits to the combined sewer collection system. The City is considering a stormwater ordinance to encourage large commercial and industrial site owners, as well as smaller site and residential owners, to implement projects that reduce storm runoff entering the sewer system.
The Stormwater Benefits Analysis was prepared to provide estimates of the existing volume of storm runoff entering the combined sewerage system. The analysis also projected an estimate of storm runoff reduction that could be obtained through implementation of a stormwater ordinance. Factors affecting runoff reduction included anticipated participation rates, existing land use and density, subsurface soil conditions, topography, and collection system conveyance and configuration.
The results of the evaluation indicated that the establishment of a stormwater ordinance to encourage private-based initiatives might provide a modest reduction in runoff to the combined sewer collection system, ranging between 11% to 19% for the evaluated precipitation events. Although stormwater ordinance implementation alone is unlikely to eliminate any of the City’s CSOs, it will become an integral part of the City’s strategy to help preserve capacity within the collection system and the WWTP. This, in turn, will allow the City to reduce CSO volumes and frequency as part of its future Long-Term CSO Control Plan. | | | | | |
| | | Author(s): John N. McClellan, David A. Reckhow, John E. Tobiason, James K. Edzwald, and Darrell B. Smith | | Publication(s): American Chemical Society, Washington D.C., 2000. | | [View Abstract] [Request Paper] | | A model based on a simplified conceptual reaction mechanism that predicts chlorine decay and the formation of THMs and HAAs was developed and calibrated. The form of the model is a system of differential equations (solved numerically). The model was calibrated using a low SUVA, low alkalinity, low bromide water. Excellent results were obtained when the model was tested using a water similar to the calibration water. | | | | | |
| | | Author(s): Peter J. Grabowski, P.E., David E. Pinsky, P.E., Edward O. Norris, P.E., Peter E. Gaewski, P.E., Brian P. Robillard, P.E. | | Publication(s): Spring 2003 Joint Regional Conference and Exhibition, Worcester, Massachusetts, April 2, 2003; published in New England Water Works Association Journal, March 2004 | | [View Abstract] [Request Paper] | | Built during the period of 1903-1905 by the grandson of Eli Whitney, the lake Whitney slow sand filtration plant marked an early use of reinforced concrete in Connecticut. The South Central Connecticut Regional Water Authority (Authority), one of the largest water utilities in CT, contemplated replacement of the plant in the historic Whitneyville section of Hamden, CT for many decades. The plant was removed from service in 1991 since it no longer was well suited to meet current and future water quality regulations. In 1999, the Regional Water Authority governing boards approved the project to replace the aging slow sand filtration plant with a new state-of-the-art 15 million gallon per day (mgd) treatment. facility designed to supply high quality drinking water, meeting both current and anticipated future water quality regulations. The design philosophy used for the project was based on an environmentally friendly approach to minimize both shortterm and long-term impacts to the environment and to the local n | | | | | |
| | | Author(s): Todd D. Kirton and Paul G. Beaulieu, Tighe & Bond Consulting Engineers | | Publication(s): Contaminated Soils, Sediments and Water – Science in the Real World, Volume 9, (Calabrese, Kostecki and Dragun, Eds.) New York, New York; Springer Science & Business Media, Inc., 2005. | | [View Abstract] [Request Paper] | | The nature of the railroad industry nearly ensures the release of petroeum hydrocarbons (in the form of diesel fuel, motor oil, lubricating oils, etc.) to the soils and subsoils along the thousands of miles of rail tracks throughout the United States. The operation of a locomotive, for obvious reasons, is dependant upon the use of these forms of petroleum hydrocarbons, and leaks, spills and accidents are unavoidable in many cases. Nevertheless, these releases may be regulated by state environmental agencies. In Massachusetts, for example, the regulations governing the cleanup of releases of oil and hazardous materials -- the so-called Massachusetts Contingency Plan, 310 CMR 40.000 -- do not exempt the railroad industry from remediating spills in excess of the 10-gallon 'Reportable Quantity'. Cleanup of spills along active rail lines, however, can be quite challenging. Rail traffic presents significant dangers to remediation personnel. Moreover, although excavation of contaminated soils is often the mos | | | | | |
| | | Author(s): Mark W. Popham, Doris S. Atkinson, P.E. | | Publication(s): Solid Waste Association of North America | | [View Abstract] [Request Paper] | | The Moretown Landfill owned and operated by Waste Systems International (WSI) provides an interesting case study in a range of technologies available for control of odors associated with landfill gas. Landfill odors are of particular concern at the Moretown Landfill. The 600-tpd landfill has historically accepted municipal solid waste, wastewater treatment residuals and construction/ demolition waste. The landfill is situated in a narrow valley that intermittently results in poor dispersion of odors. This has resulted in complaints from nearby residents and travelers on an adjacent state highway. In response to these concerns, the landfill operators have developed an odor-monitoring program that includes quantitative assessment of odors on a daily basis as well as an aggressive landfill gas control plan.The Moretown Landfill includes three separate MSW landfill areas on a 200-acre site. These areas are identified in Figure 1. The original closed unlined landfill area (approximately 12 acres) was initially equipped with seven landfill gas wells with passive solar flares. The following paper discusses the effectiveness of the solar flares at Moretown for odor control as well as operational concerns.In 1998 a pilot study was performed to determine the amount of landfill gas that could be extracted from the closed unlined landfill area through active landfill gas collection. A temporary collection system and flare were installed to gather data. Based on the success of the temporary active system, after the pilot was completed, the landfill operators continued to use the temporary system for odor control until a permanent active system was installed in 1999.The second landfill area is a 5.5-acre lined landfill cell that was capped at the end of 1999 (Cell1). This cell includes an active landfill gas collection system with eight deep wells, a condensate knockout system and a candlestick flare. The closure design also includes a passive landfill gas system to be used after active landfill gas collection is no longer required. During construction of the landfill cap, the passive landfill gas collection system was connected to the temporary active system for the unlined landfill area. This was successful in helping to reduce landfill gas odors during construction as well as reducing the pressure under the landfill cap before the active collection system for this area could be placed on-line.After the cap was completed, the collection system for the unlined landfill area and the lined Cell 1 were connected and a second pilot study was performed to determine the amount of gas that could be extracted from the two systems. Based on the second pilot study, a request for proposals for a landfill gas to energy and/or gas utilization project was developed. At this time, the landfill operators are still evaluating alternatives for gas utilization.The third landfill area is a 13.5 acre lined landfill cell that commenced waste acceptance in mid-1999 (Cell 2). The landfill operators are currently developing plans for active gas collection, which may incorporate the capability to recirculate leachate. The plans include the ability to collect landfill gas during active landfill operations to control odors. Progress and design issues associated with the leachate recirculation / gas collection project are also discussed in the paper. | | | | | |
| | | Author(s): John N. McClellan, David A. Reckhow, John E. Tobiason, James K. Edzwald, Darrell B. Smith | | Publication(s): Proceedings of the American Water Works Association Annual Conference, Chicago, IL, June 1999 | | [View Abstract] [Request Paper] | | Many utilities employ chlorine to control biological activity in their distribution systems. Chlorine residuals may be consumed by reactions with natural organic matter (NOM) and reduced inorganic substances in the water and at the pipe walls. The reactions of chlorine in natural waters may proceed over periods of several days, causing continuing changes in the chemical composition of water as it moves through distribution systems. Absence of a disinfectant residual may result in growth of pathogenic microorganisms. However, some chlorinated organic compounds that are products of reactions between chlorine and NOM including the trihalomethanes (THMs) and haloacetic acids (HAAs) may represent long term health risks to consumers. Trihalomethane and haloacetic acid levels in drinking waters are currently regulated by the EPA.
Providing adequate protection against microbial threats while minimizing chlorination byproduct formation depends not only on effective operation of treatment plants, but also on optimal operation of distribution systems. Models that can represent distribution system chlorine/chlorination byproduct reactions could be powerful design and operational tools. Previous modeling efforts have focused on chlorine, and to a lesser extent, THMs. Little modeling of HAAs or other chlorination byproducts in distribution systems has been performed to date.
Objective
The goal of this research was to develop a model for predicting free chlorine, THM, and HAA concentrations in the South Central Connecticut Regional Water Authority (RWA) distribution system. The objective was to develop a model that captures the effects of chlorine dose, temperature and pH without condition-specific calibration; that can handle mixing of waters from different sources with different NOM characteristics or applied chlorine doses; and that could be easily modified to model additional byproducts including reactive species.
Summary and Conclusions
A model for THMs, HAAs and chlorine in water distribution systems was developed and field-tested. The model utilizes a semi-mechanistic representation of chlorine/NOM reaction kinetics. Under this approach, multiple substance concentrations are tracked and local reaction rates are based on the concentrations of the reactants (chlorine and NOM sites). Good agreement between model predictions and field measurements of chlorine residuals, THMs, and HAAs was observed when the model was field-tested in the New Haven, CT distribution system. The model accounts for chlorine demand due to reactions with corrosion products in unlined iron pipes. There is no other pipe reaction component in the model, suggesting that pipe wall reactions may not be important for the New Haven system. Explicit representation of reactant concentrations, temperature and pH in the kinetic model make this approach especially well suited for “what if” modeling, modeling of reactive byproducts, and modeling systems with multiple sources of different NOM quality or different chlorine doses. | | | | | |
| | | Author(s): Nancy E. Milkey, P.G. | | Publication(s): AEHS Eighteenth Annual International Conference on Contaminated Soil, Sediment and Water, Amherst, MA, October 2002 | | [View Abstract] [Request Paper] | | In 1987, a release of petroleum was identified at an undeveloped property downgradient of a former drop forge. The drop forge operated from approximately 1900 through 1979. Subsequent delineation of the release determined that the source was within the industrial building area housing the drop forge. In August 1990, nine fuel oil underground storage tanks (USTs) were removed from the industrial complex. While installation dates are not clearly documented, the tanks may have been installed as early as 1909. During the removal, large holes were identified in the USTs where gauging sticks had punctured the bottom of the tanks.
The site is surrounded by water on three sides and throughout the investigations sheens have been observed on the surface water. In 1992, three 36-inch recovery wells were installed in two areas of the site to prevent future outbreaks of fuel oil to the adjacent surface water. In the 1990’s, a detailed hydrogeologic investigation was completed to identify the presence of preferential pathways and provide data for the design of a comprehensive hydraulic and physical barrier. An extensive soil boring program, including the use of a cone penetrometer, was undertaken. The results of the investigation indicated that the majority of contaminant transport is occurring through a sand and gravel layer.
In 1997, seven additional recovery wells were installed in one area of the site to prevent additional outbreaks to the adjacent ponds and canal. However, very low groundwater removal rates were obtained due to the minimal thickness of the sand and gravel layer across this portion of the site.
In 1999, a Waterloo® Barrier was installed in a V-shaped pattern to prevent outbreaks to the surface water bodies and provide a pooling-effect to assist the recovery wells in removing petroleum-impacted groundwater from the area. Following the barrier installation, soil excavation was conducted to remove petroleum-impacted soil from the downgradient side of the barrier. To-date very few recurrences of sheens have been observed on the adjacent canal and ponds and the pumping rates have significantly increased in this area of the site. | | | | |
|
|
