Complex Hydraulic Systems
WWM is a nationally recognized expert in the field of complex hydraulic system analysis and design. Services are provided for problem trouble shooting, forensic investigation, hydraulic analysis and the design pumping and piping systems. Often as pumping systems age the resultant changes in energy forces result in hydraulic anomalies. Many times existing pumping systems require upgrades or enhancements to achieve greater delivery rates. Most often new facilities require design for multiple pumps operating to meet initial conditions which must then be capable of overcoming future demands as the project matures.
Typical WWM complex hydraulic projects include residential grinder pump sewer systems utilizing multiple pumps and multiple force mains, parallel force mains for main sewage pumping facilities designed on extended year life cycles, very large volume (> 200 MGD) pumping system design, water meter test bench facilities, inverted gravity sewer siphons, municipal water system pressure and flow analyses and river and levee pumping systems. Frequently WWM is asked to provide forensic investigations into the reasons for system failures, water hammer, vibration, cavitation, negative pressure variances, siphon effects, air entrainment and other hydraulic irregularities.
Beginning with the passage of Public Law 92-500 – “Water Pollution Control Act Amendments of 1972”, commonly known as the “Clean Water Act”, every municipality was faced with either upgrading or constructing a new wastewater treatment plant to meet “secondary” treatment standards as part of the national effort to enhance the quality of the Waters of the United States. Following fifteen years of intense engineering and construction virtually every community was operating a then state of the art wastewater treatment plant. By the mid 1980s it was recognized it would be twenty five years before the new plants would require engineering for the upgrades and expansions to address growth induced capacity demands, repair worn out components or install new technology based equipment or processes to meet more stringent water quality standards.
WWM and its staff have experience with the evaluation and design of more than 200 wastewater treatment plants. Beginning in 1972 with the passage of the Clean Water Act, WWM’s principal, David Rigby designed the first wastewater treatment plant funded and constructed through the EPA “Construction Grants Program”. Since that time the evaluation, design, construction and operation of municipal and industrial wastewater treatment plants has been focus of Mr. Rigby’s career and WWM’s services.
Typical WWM wastewater treatment plant projects include evaluations or existing operations and staffing, assessment of older treatment facilities needing to repair or replace worn out equipment, design for the retrofit of older facilities with enhanced or improved equipment, evaluation and design of expanded facilities including biosolids management and dewatering, process enhancements to meet stringent water quality requirements, planning and design of new stand alone treatment facilities and the design of small package plants for schools, churches and small communities for installation ahead of on-site effluent disposal.
WWM’s experience in water treatment plant engineering and design is as long as its experience in wastewater treatment plant design. That being said however, the number of constructed and operating wastewater treatment plants far exceeds the number of water treatment plants throughout the United States. The main reason for this disparity it the fact the extension of public water utility service areas is relatively straightforward as compared to the extension of public sewer service areas. As a result many more water systems expand through the installation of supplemental storage tanks, booster stations and distribution lines. Also, water service in rural areas may be dominated by individual wells and in large urban areas such as Northern Virginia and the Maryland National Capital region public water utilities may be developed to serve multiple jurisdictions while each maintains a separate sewer system.
WWM and its engineers were the first to design an “Electromedia” filtration system for treatment of groundwater for the removal of iron and manganese in Virginia in 1981. Similarly, WWM and its engineers were the first to utilize ultraviolet disinfection on a public water supply system in Virginia in 1988. WWM and its engineers are equally familiar with conventional surface water treatment plant design utilizing both package plant and large municipal cast in place technologies and pressure water treatment plant design. In 1981 WWM and its engineers designed the Silver Creek Ski Resort water treatment plant in Slatyfork, WV where the clarity and temperatures of the surface water required supplemental lime feed in order to develop the necessary nuclei for proper flocculation and sedimentation.
WWM and its engineers are extremely experienced in the design of pressure systems for all manners of water treatment applications. WWM has designed pressure systems for the treatment of surface water from both lake and river sources. WWM has further designed pressure systems for the removal of iron and manganese, gross alpha and gross beta radionuclides, nitrates, trace organics, sediments and bacteria. In absence of any published design criteria, WWM’s principal, David Rigby developed criteria for the design of hydropneumatic tank systems for use on public municipal and private water systems.
Water And Sewer Pumping And Storage Systems
WWM is perhaps best known for its expertise in the analysis and design of complex hydraulic and pumping systems for water, sewage, stormwater and industrial process water applications. At any time WWM may have as many as twenty pumping projects on its active project list. After thirty five years WWM and its engineers have designed over five hundred major pumping projects throughout the United States. WWM’s principal, David Rigby is a long standing adjunct professor of graduate environmental and civil engineering studies at The George Washington University in Washington, DC. Among his teaching assignments is Advanced Sanitary Engineering Design which he commonly refers to as “Applied Fluid Mechanics” and / or “Pumping System Hydraulics”. In that course Mr. Rigby teaches the three governing equations for both open channel flow and closed pipe hydraulics being “Continuity”, “Energy” and “Momentum”. He also teaches single and parallel force main hydraulics, multiple and variable speed pumping applications, design of water booster stations, cavitation and its causes and mitigation techniques, elevated and ground water storage tank siting criteria, hydropneumatic tank sizing, gravity sanitary and storm sewer design and inverted siphon design.
All WWM engineers are fully adept in the design of sewage pumping stations. With the exacting yet varying standards for pumping station design of the various municipalities in the Washington DC metro area, WWM stays abreast of the latest technologies including cured polymer aggregate corrosion resistant structures, variable frequency drive motor controllers for widely varying flows, the latest in SCADA (Supervisory Control and Data Acquisition SCADA) systems, corrosion resistant lining and materials applications, integrated solids maceration, wet well mixing and aeration, odor control and bypass pumping all designed to meet the latest OSHA confined space standards.
WWM and its engineers are fully versed in the design of water booster stations, sewage pumping stations, stormwater management and flood control pump stations and industrial process pump and conveyance applications where the fluid materials may be hazardous or corrosive, highly viscous, high in temperature or have high concentrations of fats, oils and greases. WWM and its engineers are equally experienced in hydraulic systems utilizing split case and turbine pumps, submersible and dry pit pumps, positive displacement and progressing cavity pumps, self priming and Archimedes screw pumps and chemical feed systems. Storage and hydropneumatic tanks selections are matched to the specific duty requirements and may include below ground clear wells, raw and finished ground storage tanks, hydropneumatic tanks for both residential and fire flows and elevated storage tanks.
Water And Sewer Master Planning
WWM and its principal David Rigby have a long history of developing master plans for water and sewer infrastructure. Beginning in the early 1970s with the passage of the Clean Water Act and the accompanying Construction Grants Program and coupled with the US Farmers Home Administration’s Rural Community Assistance Loan and Grant Program many towns and counties initiated the development of new water and sewer systems. During that era and with the easy availability of grant funds most communities took advantage of the opportunities to include longer range water and sewer demand forecasts in their infrastructure planning programs. In virtually every case the new water and sewer system alternatives were compared and evaluated for fifty year life cycles.
While the decade from 1972 – 1982 saw almost every community in the US initiate new water and sewer infrastructure planning and construction programs it was recognized that once those systems were installed it would be at least a twenty year wait before one of three things would happen and there would again be another boom in infrastructure planning, design and construction. As it is often said, “no one ever buys two treatment plants” so for a community to seek planning and design services either first the existing plant and system capacity had to be reached and additional capacity needed, or second the existing systems became worn out and in need of replacement or upgrade to a more efficient technology or third the regulatory agencies would impose more stringent water quality requirements which would require the installation of advanced treatment systems.
Over the course of the past thirty five years WWM and its principal Mr. Rigby have seen the consequences of the early planning and design processes, have watched systems grow and have observed the impacts of time, the advancements in technology and the impacts of the imposition of stringent regulatory requirements. Throughout the period when the infrastructure systems matured the local politics and the philosophies of special interest groups clearly had greater impacts on the sustainability of the master water and sewer programs than any technical issue or regulatory requirement. Simply, the local politics determined the land uses which in turn dictated the population density and the rate at which demand for water and sewer service could occur. Complicating the matters is the fact most local governing bodies have elections at least every two years and most elected officials see the offering or withholding of water and sewer service as their most effective means of controlling growth in their community.
WWM and its principal David Rigby have a long history of experience with industrial wastewater processes and the treatment of industrial wastes. Beginning in 1980 the firm first worked with a division of McCormick Foods in Bedford VA which made breaded chicken patties and nuggets for sale to Burger King and McDonalds. The experience gained from that work led Mr. Rigby and WWM into an extensive program of industrial process systems, waste minimization, pretreatment facilities and wastewater treatment plant design and operations. Since then WWM has worked for virtually every industry category and its industrial clients have included such notable companies as Coca Cola, Pepsi Cola, Kimberly Clark, Westvaco, Amoco, Smithfield, Carolina Turkeys, Wampler Foods, Deans Foods, Kraft, Genstar, FMC, Tyson’s Foods, Holly Farms, Oscar Meyer, Shenandoah’s Pride, Lance Foods, Burlington Industries, Fieldcrest Cannon, Dominion Semiconductor, Micron, E.I. DuPont de Nemours, Tolkoff Industries, etc.
Notably in 1986 Mr. Rigby was selected by the US Small Business Administration to be its representative to the People’s Republic of China as part of its 5 Year Plan to discuss industrial wastewater pollution and water conservation. The seeds of that work are now beginning to mature and bear fruit as China is now entering the world economic markets. In 1990 Mr. Rigby again worked outside the US in response to Mexico’s recognition that pollution from industries, particularly in the Valley of Mexico and such places as Tijuana, Guadalajara, Veracruz and the maquiadora region along the Rio Grande River. During that period WWM and Mr. Rigby wrote developed environmental impact assessments and designed approximately thirty industrial wastewater treatment systems. In 1994 Mr. Rigby was selected by the Asian Development Bank to lead a technical team to Bangkok Thailand to study the extent of the industrial pollution in the Changwat Samut Prakarn and develop the basic program for long term waste minimization and pollution control. At the time of the study there were approximately 3,000 unregulated industrial polluters in the region and in 2005 the Thai government announced had completed the initial phase of construction of the long term infrastructure improvement program.
WWM and its engineers offer special studies for its clients to address a variety of unique needs. Such services may include the planning and development of pilot tests for either new technology applications or to address the changing pollutant characteristics from modified industrial process water streams. In one instance when Burlington Industries planned to modify its denim operations to “prewash” the fabrics prior to distribution WWM developed a pilot plant program to simulate and analyze the effects the added indigo dye, sizing and detergents would have on the existing wastewater treatment plant including increased oxygen uptake rates, increased sludge production and the need for increased power to run larger blowers and mixers.
WWM also offers “on call” services for licensed water and wastewater treatment plant operations and related studies for evaluating the efficiency of wastewater treatment plant operations by analyzing such things as sludge production, sludge wasting rates, mixed liquor concentrations, food to microorganism ratios, and diagnosing and troubleshooting problem areas. Hand in hand with process analysis WWM provides services to evaluate the labor utilization rates as compared to national averages, helps develop asset management programs and performs utility risk and security assessments. On several occasions WWM formally valued the infrastructure assets owned by private, industrial and commercial entities for the purpose of receiving federal tax write-offs upon donation to the local municipal service provider.
Forensic Investigations and Litigation
WWM has a long history of offering special services for forensic investigations and for litigation in support of construction project claims. Forensic investigations often include identification of the causes of hydraulic anomalies such as water hammer, vibration chattering, unwanted siphoning and cavitation and then develops corrective action plans to mitigate the problems. Forensic investigations also may include the identifying the reasons for pipe, pump or system failures, the causes of biological die off in treatment plants including identification of the causative agents of harm, predicting the results and consequences of introducing industrial wastes into domestic systems and predicting the rates of component deterioration.
WWM and its principal David Rigby also has a long history of serving as an expert witness for the investigation and then testimony relating to engineering, construction and operations claims for all manners of water and wastewater problems. Notably, Mr. Rigby acted as the investigative and testifying expert witness on behalf of the South Carolina Department of Wildlife and Marine Resources on a major fish kill along seventeen miles of the Saluda River against the municipality, contractor and engineer responsible for allowing sludge to accumulate in a tributary to the river and against another State agency which had data available to it to have averted the problem and then failed to act to protect the river fishery resources. In another notable case Mr. Rigby defended a tannery against suits filed by the EPA and the State of Kentucky alleging violations to the Clean Water Act. In another instance Mr. Rigby acted as an expert in two cases brought by the private utility against the State of Indiana for failure to recognize expanded plant capacities because it had been using an outdated review manual that didn’t include currently recognized pollution control technology applications and procedures as being valid. Recently, Mr. Rigby served as an expert on behalf of a developer who had relied on an engineer to design and build a wastewater treatment plant to serve his project in Huntsville AL. Upon start up the treatment plant failed to function properly and produce an effluent which met the permit discharge limits, consequently a judgment was levied against the engineer.
WWM is one of the leading experts in the field of on-site disposal of sewage effluent. Beginning in 1979 WWM and its engineers have been evaluating soils and developing land based effluent disposal systems when connection to municipal systems was either not possible or not preferred. While WWM engineers are not licensed soil scientists they all have ample field experience with which to initiate planning efforts and quantify the levels of involvement anticipated by the various professional team associates including soil scientists, hydrogeologists and soil evaluators. From the years of 2002 – 2005 Mr. Rigby was the head of the task force investigating the alternatives for on-site sewage disposal in the Black Belt region of Alabama.
Mr. Rigby was the first engineer in Virginia to utilize a peat system for a home treatment system in Louisa County when soil conditions prohibited the installation and use of a conventional drainfield. WWM also is experienced with the design of wastewater treatment plants ahead of spray irrigation, drip irrigation, low pressure distribution sand mounds and re-circulating sand filters. In 2007 Mr. Rigby was an active member of the Virginia Legislative Committee which developed new regulations for the design of non-conventional on-site systems. An important key consideration of this far reaching initiative was the requirement that all non-conventional systems must be inspected at least annually by a licensed professional operator trained in the design and operation of on-site system technology who is required to submit inspection reports and recommendations for further maintenance to the Virginia Department of Health. Now for the first time the cost of operating an on-site wastewater disposal system approximates the cost of connection to a municipal sewer system.
WWM is extremely experienced in the application and receipt of environmental permits at all governmental levels. Dating back to the early 1970s WWM engineers have been working with the Virginia State Water Control Board, the Department of Health and the Department of Environmental Quality. Although headquartered in Northern Virginia WWM engineers have successfully developed and permitted projects by the Maryland Department of the Environment, the North Carolina Department of the Environment and Natural Resources, the Delaware Department of Natural Resources and Environmental Control, the South Carolina Department of Health and Environmental Control, the Las Vegas Valley Water District, the Kentucky Department of the Environment, the Indiana Department of Environmental Management, the Wisconsin Department of Natural Resources, the Tennessee Department of Environment and Conservation, the Alabama Department of Health, the Texas Commission on Environmental Quality and the West Virginia Department of Health.
WWM is further experienced in the application and permitting to federal water quality jurisdictional agencies including the US Environmental Protection Agency, the US Army Corps of Engineers and the US Coast Guard. Permit experience includes numerous NPDES permits required by the Clean Water Act, state and local health permits, all local utility reviews and local building permits as required by the BOCA and International Building codes, department of transportation permits, and permits for well development and the deep well injection of treated wastewater treatment plant effluent.
Dating back to early 1970s WWM engineers worked to develop projects funded by the numerous federal programs whose purpose was to provide financial assistance to rural communities as they developed new communitywide water and sewer systems. WWM’s experience included extensive work with the EPA Construction Grants Program which was a major source of federal funds for the construction of publically owned treatment facilities. The grant application work involved the development of Phase I engineering studies which included Sewer System Evaluation Surveys, the development of user rate schedules which accounted for capital requirements, operation and maintenance costs, debt repayment, replacement reserves and depreciation, and the recognition of the variable costs due to organic and flow contributions leading to the development of industrial user charges.
In addition to the EPA programs WWM had extensive experience with US Farmers Home Administration Loan and Grant program which had been replaced by the USDA Rural Community Assistance Program, the Appalachian Regional Commission grants, the Office of Economic Development Grants, Congressional Earmark Grants, US HUD and Department of Housing and Community Development Block Grants and EPA Water Quality Improvement Grants. Besides having experience with federal funding programs WWM has extensive experience with such state programs as community development block grants, state revolving loans for sewer projects, DEQ water quality improvement grants and VDH low interest water system loans.
WWM prides itself in its long term client and sub-consultant relationships. Truly, WWM’s success and lifetime achievements can be attributed to its unwavering dedication to its clients and their needs. Classically, CWE’s first project job number 7901 was the Town of Fincastle Wastewater Collection and Treatment System in 1979. Twenty five years later WWM’s project 0401 was the Town of Fincastle Upgrade and Expansion of the Wastewater Treatment Plant.
In 1980 CWE first worked with Mabry Engineering, structural engineers and Foundation and Materials Engineering, geotechnical and foundation engineers from Columbia, SC on the Silver Creek Ski Resort project in Slatyfork, WV. Since then Mabry and F&ME have remained WWM’s primary structural and geotechnical sub-consultants for all its water and wastewater projects.
During the 1980s Mr. Rigby served as corporate level environmental consultants for both McCormick and Company and Burlington Industries working on projects throughout the continental US and Mexico. In such instances the corporate executive team would send Mr. Rigby to the various operating division and then to the various manufacturing plants to provide consulting and assistance in the fashion desired by corporate management.
During the 1990s WWM became recognizes for its pumping station experience by the US Home Corporation and the Prince William County Service Authority (PWCSA). In the past fifteen years WWM has acted as the sole engineer to provide design and permitting services to US Home and its successor, Lennar for all regional development projects where sewage pump station, water booster stations and water treatment plants were required. In 1995 WWM’s submission of the to the PWCSA of the Heritage Hunt sewage pump station on behalf of US Home prompted it to adopt many of the pump station design elements as standards of excellence for future pump station work in the County.