Environmental and Pipeline Engineering 2000

Thirteen lab-scale constructed wetlands treated a synthetic, slightly basic mine water containing 34.2 mg/L SO₄^2–, 50 μg/L Pb and 300 μg/L Zn. Data from over two years operation showed an average removal of 90% for lead and 72% for zinc, respectively. The pH of the effluent was reduced from 8.0–8.5 to near neutrality. Temperature, hydraulic loading, and substrate composition generally did not affect treatment efficiency. Sulfate was completely removed, likely by sulfate-reducing bacteria. A study of the adsorption capacity of various wetland substrates showed a substantial adsorption capacity for lead and zinc. Measurements on sediments indicated substantial co-precipitation of lead and zinc with iron oxyhydroxides at the gravel lens in the front of the wetlands. Sequential extraction of wetland sediments showed that lead was mostly in the exchangeable and Fe/Mn oxide fractions while zinc was mostly in the Fe/Mn oxide and organic fractions. Therefore the major removal mechanisms of these metals in constructed wetlands seems to be by co-precipitation with Fe/Mn oxide and adsorption on organic matter.

Non-point source pollution to the nation's waterways continues to be a major issue in this new millennium. One of the major sources of this pollution is poorly operating on-site and centralized treatment systems. Clearly there is a necessity for alternative on-site systems to meet the needs of the public where conventional systems cannot. From an environmental standpoint it is also advisable to treat waste on site in order to return treated waters to their point of origin and maintain the natural hydrological balance. The traditional approach to designing constructed wetlands has been to use gravity-flow subsurface systems. Both Environmental Protection Agency [U.S. EPA, 1988] and the Tennessee Valley Authority [TVA, 1993] have published design literature on gravity flow systems. Recently TVA has developed a new technology that relies on a reciprocating reactor system to enhance nitrogen transformations within the wetlands. The reciprocating technology was recently granted a patent [Behrends, 1999] and these systems are currently being used in four states. This paper presents an analysis of operating data from both types of systems operating in North Alabama to determine if there are any significant differences in performance.

A subsurface flow constructed wetlands (CW) system, located in a neighborhood consisting of a small housing development and a golf course outside of Lincoln, Nebraska, was studied for its effectiveness as a small community wastewater system. Extensive monitoring has been conducted biweekly since June 1996. Prediction models for soluble CBOD₅ NH₃—N, and TP removal in CW were employed for comparison with the field data. It was found that the disappearance of BOD₅ and NH₃—N could be approximated using first-order kinetics, but the kinetics of TP removal were unclear. The reduction rate constants regressed from the field data were found to be lower than literature reported values.

At the Naval Training Center in Great Lakes, IL, the reliability and continuous operation of a 450mm (18 inch) O/ forcemain was of utmost importance. In February of 1998, the Navy Public Works Center was faced with two breaks in the subject 25 year old ductile iron force main piping. Not only did this threaten the Navy's continued operation of their pump station, there were also environmental concerns as the pipeline is located under a lakefront access road and is very near a recreational beach area on the shore of Lake Michigan. Using best value engineering, the Navy Public Works Center chose to mitigate their problems and provide system life extension through the use of a cured-in-place lining system designed specifically for pressurized piping systems.

In this paper, the state of urban sewers Europe is discussed. Strategies for the design, inspection, diagnosis and rehabilitation are explained and compared in various countries (France, United Kingdom, Scandinavia and Netherlands). Recommendations for a consistent approach of inspection, diagnosis and rehabilitation are then given. These recommendations are based on the results of studies conducted for the European Union to harmonize maintenance strategies and to promote sustainable development of underground urban utilities.

This paper describes of an experimental soil grouting work around an aqueduct diagnosed as structurally deficient with an internal jacking internal test. In order to grout the Fountainebleau sand, known as non groutable with hydraulic products, several grout formulae made with micronized cements (slag and fondue) were tested. The grouting efficiency was controlled using the ultrasonic method, the electric method and the geological radar method. These controls showed that the grouting produces an arch above the conduct. This arch permits the transmission of vertical loads to the surrounding soil; these loads were initially supported by the conduct. The mechanical analysis realized with the loading internal test showed that the conduct has, after grouting, an acceptable safety factor. The paper describes the results of this experimental soil grouting work around a part of the aqueduct diagnosed as structurally deficient with the internal jacking test.

This paper discusses a value engineering study, design, and construction of a sanitary sewer siphon using high density polyethylene (HDPE) pipe in San Juan, Puerto Rico. The value engineering study evaluated pipe options and construction methods and recommended the use of HDPE pipe constructed in the wet for the Rio Puerto Nuevo river crossing. The design of the pipe included development of the horizontal and vertical alignments, pipe hydraulics, selection of pipe wall thickness, and pile clearance analysis. The HDPE pipe is joined using heat fusion, launched into the river, and covered. This paper also discusses details of the construction, which is in progress.

The San Diego County Water Authority (Authority) has over 400 kilometers (km) of large diameter pipelines that provides up to 95 percent of the water to San Diego County's 2.7 million people. In this 400 km is 133 km of prestressed concrete cylinder pipe (PCCP) manufactured between 1958 and 1982 ranging in diameters of 168 cm to 244 cm. In order to provide a safe and reliable supply of water to San Diego County, the Authority implemented the Aqueduct Protection Program (APP) in 1992 which includes the condition assessment of the Authority's PCCP. Part of the program consists of developing and researching new non-invasive/non-destructive inspection procedures to determine the condition of existing PCCP. In June 1999, the Authority experimented with Remote Field Eddy Current/Transformer Coupling (RFEC/TC) measurements on 5 km of 175 cm PCCP installed in 1959. This paper discusses the equipment, investigative procedures, results and accuracy of RFEC/TC.

As the population in Central Colorado is exploding, the water demand in the region is also rapidly increasing. Existing water storage facilities are no longer sufficient to provide for the nearly 400,000 people in the water service area. Increasing the water storage volume has become an urgent, and quite compex issue. Focused on in this discussion are the current water storage plan, impacts of a new dam and reservoir on the region, and alternatives to creating a new dam. The current water and diversion plan called the Fryingpan-Arkansas Project, is a project that diverts nearly 70,000 acre-feet of water from the Fryingpan River to the Arkansas River each year. As this plan will not be able to accommodate future water storage needs, several possible options for creating more storage space are being explored. Constructing a new dam and reservoir seems to be an obvious solution, although the consequences of such a project on the environment, the local economy, and the water rights are severe. Expanding an existing reservoir is quite possibly the next most viable option. Other possibilities, such as using drained aquifers as groundwater storage or developing a strategy for maximizing existing storage facilities, remain as potential solutions. Work continues in exploring viable solutions to the current and future water problem, although conservation appears to be the most practical option.

A commercial development company recently proposed a plan for a new business park near the historic town of Mooresville, AL. The local engineering college was asked to examine the impacts of the land use change from the current land use, agricultural, to light industry. Specifically the project consisted of analyzing stormwater caused by development of the property and runoff from the adjacent interstate onto the site. One of the main concerns was that this stormwater would flow directly into natural wetlands of Piney Creek and ultimately, the Wheeler Wildlife Refuge on the Tennessee River. The company also wanted a proposal for the best method to treat the stormwater on-site to minimize environmental impacts of development. This paper will address the design of a natural treatment and detention system for the site. The final design is for a three foot deep pond using phytoremediation with cattails and other native plant species for natural water quality treatment. Additionally the one-half acre pond will allow for solids settling to occur prior to release.

This paper presents a study performed to determine the source of Atrazine contamination in a small watershed in North Alabama. Atrazine is a widely used agricultural herbicide used to control both broadleaf and grassy weeds. After contamination was discovered in the Hester Creek watershed in the spring of last year, the community wanted to know if this was a seasonal problem or if it posed a threat to local drinking water all year long. This paper presents results of a groundwater/surface runoff transport simulation of the watershed to determine if the primary contamination could be correlated to stormwater sources or was caused by groundwater inter-flow into the creek. Preliminary results show that the stormwater components are significant, while the groundwater contributions appear to be extremely minor.

An event-based, kinematic, infiltration-excess, distributed rainfall-runoff model was developed to acknowledge and account for the spatial variability and uncertainty of several parameters relevant to storm surface runoff production and surface flow. The model is compatible with raster Geographic Information Systems (GIS) and spatially and temporally varied rainfall data. Monte Carlo simulation and a likelihood measure are utilized to calibrate the model; allowing for a range of possible system responses from the calibrated model. Using rain gauge adjusted radar-rainfall estimates, the model was applied and evaluated to a limited number of historical events for two watersheds within the Denver Urban Drainage and Flood Control District (UDFCD) that contain mixed land use classifications. The 95% uncertainty bounds obtained from the model envelop almost all observed responses at the main basin outlets for the events considered, suggesting an acceptable model structure. While based on a limited number of Monte Carlo simulations and considered events, for the two basins that were considered, Nash arid Sutcliffe efficiency scores of 0.88/0.10, 0.14/0.71, and 0.99/0.95 for runoff volume, peak discharge, and time to peak, respectively, were obtained from the model.

Dissipation of aroclor 1248 and 4,6-dinitro-o-cresol was examined under rhizosphere influences of reed canarygrass (Phalaris arundinaceae), switchgrass (Panicum virgatum), flat pea (Lathyrus sylvestris), burr medic (Medicago polymorpha), and snail medic (M. scutellata). After 135 days in growth chambers, significantly more aroclor was lost from all planted soils than unplanted soil, except soil that was planted with burr medic. In ongoing experiments, burr medic stimulated the highest loss of aroclor 1248 after 8 weeks in soil that was amended with pine needles. Less DNOC was recovered from all planted soil than initial nominal additions. The results are discussed in terms of the development of plant systems for enhanced phytoremediation of organic contaminants in soil.

The methyl derivatives of benzotriazoles, commonly called tolyltriazoles, are effective anticorrosion agents used in antifreeze at levels of about 1 g/L. In aircraft deicers and anti-icers the same compounds are used as anti-sparking agents at levels up to 1% by weight. Disposal, and run-off during application may lead to contamination of both surface and groundwater with these compounds, which have significant toxicity to aquatic organisms, both plants and animals. The triazoles are highly resistant to solar degradation and appear inert during conventional sewage treatment processes. Their fungal degradation by white-rot fungi has been demonstrated by us, and they are susceptible to a Fenton type degradation. Higher plants contain lignin peroxidase much like that of the fungi so we have investigated the potential of higher plants to tolerate and degrade benzotriazoles. At concentrations up to 50 mg/L there is little or no inhibition of plant growth but at levels above 100 mg/L there is acute toxicity to plants. In either case, the tolyltriazoles disappear from solution, until the plant is killed. Borate, which is known to be essential in lignin synthesis, has no protective effect. The free compounds have not been detected in the upper portions of plants, indicating that they are metabolized. Annual sunflowers, and common fescue have given comparable responses. Efforts to identify metabolites are in progress.

Studies were conducted at water utilities in Willmar, MN; Washington, IL and Normal, IL to determine the effectiveness of alternative treatment methods for controlling microbially-mediated water quality deterioration during distribution. Following each study, treatment modifications were made to increase the removal of microbial nutrients which lead to chlorine and oxygen depletion during distribution. A study of copper corrosion in household plumbing at Willmar, MN revealed that the depletion of disinfectant residual was stiochiometrically related to the amount of copper found in solution. Remedial efforts focussed on lowering and maintaining a more stable chloramine residual. Long-term distribution system monitoring to assess chloramine and oxygen persistence was initiated following treatment modifications. Operational changes were made at Washington, IL to accomplish the removal of ammonium ion using cation exchange. During routine softening by cation exchange, ammonium ion is initially removed and, then, released in a large pulse which fosters nitrification and anoxia in the distribution system. To moderate the accumulation of microbial growth in distribution system mains, studies of alternative aeration practices directed at the complete removal of methane were conducted at Normal, IL. Improved aeration has resulted in more persistent disinfectant residuals.

Engineers who maintain concrete water pipelines have not had adequate tools available to diagnose and cure the problems which tend to infect the pipeline infrastructure. This is rapidly changing. The advancing age of our pipeline infrastructure, and the huge investment we have in these facilities are mandating changes in the way we care for these assets.

The National Science Foundation (NSF) has estimated the total U.S. investment in civil infrastructure systems at $US20 trillion. The investment in our sanitary sewer collection systems represents a major component of this overall investment. Many of these systems are eroding due to aging, excessive demand, misuse, exposure, mismanagement and neglect. Historically, sanitary sewer collection system rehabilitation has been prompted primarily by responding to failures rather than attempting to prevent them. More municipal engineers are realizing the public health and safety as well as cost benefits that can be achieved with a proactive sewer system management system. The objective of an effective proactive sewer system management system is not just being able to collect more data regarding the condition of the existing sewer system network. The real objective is being able to use such data to make intelligent, documentable, cost-effective decisions regarding how to rehabilitate, operate, and maintain this enormous and ever-expanding network. This paper will present state-of-the-art concepts and technology for sewer collection system data acquisition, data interpretation and utilization of the data for planning for intelligent renewal of underground sewer system rehabilitation. Most municipalities do not have the financial resources to address all of the defects identified in the data acquisition process; therefore, it is essential that data be integrated into an effective management system. This paper will be presented in two parts. The first part will focus on the state-of-the-art technology for sewer collection system condition assessment. The technology that will be featured in this part of the paper will be the Sewer Scanner and Evaluation Technology (SSET). The second part of the paper will focus on a North American technology evaluation program.

The gravity sewer pipe has served as the primary collection component for urban and suburban wastewater systems for many years. Yet elements of design, construction, maintenance and rehabilitation of these systems are still evolving. The desire to provide better customer service, meet the current regulatory climate surrounding sanitary sewer overflows, and stem the deterioration of these aging sewers is driving further development in these areas.

Methyl tert-butyl ether (MTBE) is an important groundwater contaminant. Gasoline spills and leaks from pipelines, underground and above ground storage tanks and other transport modes are major sources of MTBE contamination. By measuring plant water-use and the concentrations of MTBE in plant water, we obtained the mass fluxes of MTBE transported by alfalfa plants (Medicago sativa) grown in soil channels contaminated with MTBE. Even with the same contaminant concentration in the growth channel, alfalfa plants took up MTBE non-uniformly. The more vigorous the growth of plants, the higher the MTBE concentration in the plant water, and the more MTBE removed by the plants. Measured concentrations of MTBE in plant water in stem segments decreased with distance from the channel soil surface.

The H₂O₂/UV advanced oxidation process (AOP) was investigated to determine byproduct formation under different experimental conditions (pH, alkalinity, and H₂O₂/UV dose). A key factor in the efficiency of the AOP was the dissolved oxygen concentration. Gas chromatography/mass spectrometry (GC/MS) analysis was used to identify byproducts resulting from oxidation under oxygen-rich and oxygen-limited conditions. Resultant oxidation byproducts were analyzed for their susceptibility to biological degradation. Biodegradation rate constants were determined and modeled for the primary byproducts of the advanced oxidation process. Inhibition resulting from the presence of multiple byproducts in a biological system was investigated as well. Effects of process parameters such as pH, alkalinity, and residual H₂O₂ concentrations were also determined.

The Southern Valley Development Project (Toshka) is a major project located 1,000 km south of Cairo, Egypt. The project involves pouring Nile water out off Lake Naser into the desert in order to reclaim parts of it for agricultural use. The Toshka project is considered one of the largest projects in the world with its unique pumping station that delivers 25 x 10⁶ m³/day (~300 m³/sec). As a result, safety is a major concern and maximum protection measures against Waterhammer should be incorporated into the project's design. Waterhammer analysis will provide the required protection that is needed for both pump and pipeline. This paper contains numerical model that simulates pump power failure followed by a valve closure for a pumping system drawing liquid through a single pipeline and discharging it into a reservoir. The method of characteristics was used to solve the transient pressures in a liquid-filled piping system. Transient conditions caused by an emergency pump power failure are analyzed and studied with respect to the Toshka pumping system. A proposed valve closure is presented and the resulting pressure envelope is shown.

Nearly every large wastewater utility in the world is unique with different factors affecting each. Some have significant topographic changes while others are flat. Some collection systems are well above the groundwater table while others must operate submerged. One factor that affects most systems is rain and groundwater infiltration/inflow (I/I) into the gravity wastewater collection systems. During storm events, this I/I can have high peaks which are difficult to measure or reduce. To prevent illegal discharges of wastewater prior to treatment, the utility must transmit and treat all flow in the system, or somehow reduce it. This paper will investigate means of evaluating a relatively flat, submerged wastewater collection system to reduce peak flows during storm events and minimize sanitary sewer overflows (SSOs) which can threaten public health and the environment. The specific focus of the paper will be the Miami-Dade Water and Sewer Department's Collection System in Miami-Dade County, Florida, and efforts to quantify and reduce peak flows. These flows can cause tremendous strain on the treatment facilities and operation of the County's 926 pump stations, and lead to SSOs. Since 1993, Miami-Dade County has been undergoing a $1 billion upgrade to its wastewater facilities with the main focus on reducing SSOs. The major portions of this plan include reducing I/I and increasing the transmission capacity of the pump stations and force mains plus increasing treatment and disposal capacity. Early upgrades to pump stations and force mains were based on average flows with some extra capacity for peaks; however, actual peak flow data was not available for design. The estimated flows were based on annual domestic water usage and night flows taken twice a year (once in the wet season and once in the dry season). In addition, designs incorporated reduced I/I from the ongoing I/I Rehabilitation Program. Unfortunately, it has been found that the common techniques used to reduce normal I/I is having little effect on reducing peak flows caused by RDI/I. New technologies have been developed since the program inception to better quantify the peak flows and prioritize rehabilitation. In addition, several alternatives have been developed to address peak flows whether it be at the source or at the treatment plants (e.g., service lateral RDI/I reduction versus chemical treatment processes). This paper will investigate each of these subjects and suggest a means of proceeding toward the County's goal of reducing SSOs.

Every sanitary sewer system, regardless of its age, size, or location, contributes inflow and infiltration (I/I) to the municipal wastewater collection and treatment facilities. The cause of excessive I/I is due to an aging infrastructure that has not been adequately maintained. This paper presents current methodologies to identify, evaluate, and rehabilitate the municipal wastewater collection system.

Despite the growing number of sewer rehabilitation processes and products, few reports have been available in the literature about their effectiveness for I/I removal, SSO reduction, and water quality improvement. This paper presents results from flow monitoring studies, overflow reports, and water quality studies conducted over the past nine years in Nashville, Tennessee. I/I quantity, SSO duration and fecal coliform concentrations were selected as the parameters most likely to be affected by sewer renewal projects. To develop a data base of objective measurements of sewer rehabilitation effectiveness, twenty seven projects conducted in the Nashville, Tennessee, OAP (Overflow Abatement Program) were analyzed which included 83,781 m (274,871 ft) of sewer lining or replacement. This represents about half of the rehabilitation work conducted through this program since 1990. The goal of the program is to improve system characteristics, recapture capacity, and reduce I/I so the sewers can carry the peak flow from a design storm with a specified recurrence probability, without overflows. The most stringent design criteria used a 5-year, 24-hour storm. Linear regression analyses were used to predict the I/I expected from the selected design rainfall. Some of the projects showed sufficient I/I reduction to allow a five-year payback from treatment costs avoidance. A cumulative annual I/I reduction of 10.36 x 10⁶ m³ (2,737 million gallons) has been documented for these projects. The trend of results indicate that an I/I removal rate of approximately 10,000 m³ /year/100m of lining (8.2 million gallons/year/1000 ft of lining) may be expected from rehabilitating deteriorated sewers in the Nashville area. I/I removal rates will likely vary in different locations due to groundwater levels, annual rainfall, previous construction techniques, soil types, etc. Accordingly, sewer rehabilitation programs should include procedures to measure I/I removal effectiveness as a program progresses. For I/I control programs that are just beginning and which lack performance data, the rehabilitation experience in Nashville illustrates a procedure to develop performance measures and procedures for long range program planning. Once defined for a given area, that removal rate can be coupled with rehabilitation construction costs and I/I quantities from flow monitoring. Knowing the relationship between I/I removal effectiveness and the quantity of sewer rehabilitation by lining required can assist planners and municipal officials in projecting the long-term program costs for sewer rehabilitation. State regulatory actions are increasingly focused on streams that have not achieved water quality levels appropriate for their designated uses. Lists of these streams have been published as required by Section 303d of the Clean Water Act. In many cases these streams have been listed because of SSOs or CSOs (separate sanitary sewer overflows or combined sewer overflows) that discharge during wet weather conditions. However, long-term water quality studies on tributary streams in Nashville have indicated that background or non-point pollution sources may be significant. In some cases, removal of wet weather discharges may not be sufficient to achieve compliance. TMDLs (total mass discharge limits) may be needed.

Trenchless assessment and rehabilitation will continue to find major use in pipeline asset management. Compared to a handful of such technologies being available to either the city manager or an industrial client a decade ago, nowadays, we have hundreds of technology holders in the market place. More and more clients are opting to privatize their underground pipeline network. So, the net outcome is clients want the most done for the least cost. The relationships among licensees and licensors are also eroding very rapidly to the point that many licensors are going back and buying their proprietary rights from their installers having seen the profit margins drop significantly in the past few years. It's practically a price war in this business of pipeline renewal by trenchless technology and the market will go through a major consolidation resulting in a few winners and many losers. Although the American trenchless renovation market is huge, most companies will lose in the American contracting climate, given the harshly competitive environment. Then, who will win and stay in this market or in any market for that matter? For example: the market in the coming years will decide whether spiral-wound pipe technology can either compete or offer something superior against either Cast-in-Place-Pipe or Fold-and-Form technology? This paper will highlight the evolution of the trenchless pipe rehabilitation business and will provide bold predictions of this market for the next 10 years.

Remediation of contamination sites has become a major activity for engineers and for society. The American Society of Civil Engineers has prepared a manual to provide information for site owners, consultants and contractors involved in the cleanup process. This paper provides an overview of the introductory material in the manual. Site remediation is the last and worst way of handling hazardous materials, and every effort should be made to avoid it. When they are unavoidable, cleanup efforts are governed by local, state, and federal regulations. Remediation may begin with emergency measures to contain a spill, but will always involve careful characterization of the site, review of possible remediation methods, selection of the best method, design and planning, and finally implementation of the cleanup. Community involvement is always valuable. The manual describes the complete step-by-step process necessary for a major site remediation as well as expedited approaches that are quicker and cheaper and that may be appropriate in many cases.

The Manual and Reports on Engineering Practice Number 99 published by ASCE titled "Environmental Site Characterization and Remediation Design Guidance" was completed by the Environmental Engineering Division, Remedial Investigation/Feasibility Study/Remediation Design Manual Task Committee in 1999. This paper provides a summary of information contained within the "Site Characterization" Chapter of the Manual. Site characterization is one of several phases of an investigation and cleanup program for a given location. Before embarking upon the evaluation of remedial alternatives, it is important that the site be adequately characterized. A poorly characterized site could result in delays and other problems during remediation implementation. Before carrying out a site characterization, the investigator must first identify the purpose and define the scope of the investigation. Available background information is reviewed to focus the characterization and assist in the interpretation of data. Information to be considered as part of the planning process includes site history, physical features, and contamination source characteristics. Methods for obtaining site characterization data can be evaluated in terms of practicality, economics, simplicity, versatility and safety. Methods commonly used for obtaining and analyzing samples to characterize soil, surface water, groundwater, and air are presented. Methods presented for collecting soil samples include geophysical techniques, grab soil sampling, hand augering methods, trenching, soil vapor surveys, direct push methods, and drilling. Some techniques for collecting samples of sediment, surface water, groundwater, and air samples are presented. Data obtained as part of the site characterization is reviewed to verify consistency with objectives of the characterization investigation.

Within Chapter 2 of the American Society of Civil Engineers' (ASCE's) Environmental Site Characterization and Remediation Design Guidance (ASCE Manuals and Reports on Engineering Practice No. 99; ASCE, 1999), standard methodologies for the completion of human and ecological risk assessments are provided as an example and a starting point for understanding the risk assessment process. While it is important to understand the technical manner in which a risk assessment is conducted, one must first understand the role of the risk assessment in a site characterization and remediation design project prior to embarking on one. A risk assessment can serve a variety of important roles throughout the site characterization and remediation design process.

The process of developing and evaluating remediation alternatives can be divided into steps: 1) Establishment of remedial action objectives. 2) Development of remediation alternatives (scenarios). 3) Screening of alternatives. 4) Detailed analysis of alternatives. Development of remediation alternatives involves definition of general response actions, which are particular approaches to remediation for a contaminant or class of contaminants in one medium; identification of technologies, which involves choosing specific remediation processes for contaminated media; screening of technologies, in which process options or entire technology types are eliminated, principally on the basis of technical implementability; and assembly of technologies into remediation alternatives, which are scenarios for clean up of an entire site or operable unit. Alternatives are further screened for overall effectiveness in protecting human health and the environment, for technical feasibility, and for implementability. Technical feasibility is the ability to construct, reliably operate, and meet technology-specific regulations until remedial action is complete. Implementability or administrative feasibility is the ability to obtain approvals from various agencies, acceptability to the community, the availability of services and capacity to construct and operate the alternative, and the availability of specific equipment and specialized labor. Detailed analysis can be broken down into the following components: (1) further definition of each alternative, as appropriate, with respect to volumes or areas of contaminated media, technologies to be used, and performance requirements associated with those technologies (2) assessment of each alternative against evaluation criteria, and (3) comparative analysis among alternatives to assess relative performance with respect to the evaluation criteria. Under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA or "Superfund"), alternatives are evaluated against nine criteria: (1) short-term effectiveness; (2) long-term effectiveness; (3) reduction in toxicity, mobility, or volume; (4) implementability; (5) cost; (6) compliance with applicable or relevant and appropriate requirements (ARARs); (7) overall protection of human health and the environment; (8) State acceptance; and (9) community acceptance. Once the alternatives have been individually assessed against the evaluation criteria, a comparative analysis is conducted to evaluate the relative performance of each alternative. In order to streamline the process of evaluating remediation alternatives, the U.S. EPA has developed presumptive remedies that are standardized remediation alternatives commonly used to solve particular types of environmental problems.

The term `expedited' usually brings up thoughts of special parcel delivery, with guaranteed one-day or next-day delivery. However, in some parts of the world, items that are not `expedited' never arrive at the desired location in time for use in the intended project. This chapter should be read and used more with this second view, rather than the first. Thinner margins and tighter schedules require that many projects be expedited in terms of tracking and accounting costs, slippages, and variations from that which was initially anticipated. Three approaches are discussed in developing an expedited project — streamlining, quick tools, and early action. The basic ideas behind the use of these approaches are the same as you find in every industry. The basic knowledge required is: 1) Know where you are going (what result do you want?) 2) Know the territory (it really helps when you get lost) 3) Know at least one route to get to your destination (a baseline or benchmark) 4) Know your team (you can't convince them to pull together if you don't know who they are) 5) Know the rules (regulations) 6) Know which tools are appropriate to the present task.

It has been proven and well documented during the past thirty (30) years that plastic pipe material, i.e. thermoset and thermoplastic resins, have a stress regression characteristic. Early testing for the Plastic Pipe Institute during the 1960's by several recognized laboratories developed stress regression values for various plastics. This testing procedure is now characterized in ASTM D 2837 for thermoplastic resin pipe. This was subsequently completed by various laboratories for thermosetting resin pipe and is characterized in ASTM D 2992 testing standard. Testing for external pressure for an unconfirmed specimen is provided in ASTM D 2924. Testing for external pressure for a circumferentially confined specimen has been completed, in part, by the Trenchless Technology Center, Louisiana Tech University, Tulane University and others. An ASTM test procedure is currently being developed for confined liners in an external pressure environment.

Faced with EPA administrative orders and consent decrees, several South Florida municipalities initiated extensive sewer system rehabilitation programs in the early 1990's. Given the availability of numerous and varied repair technologies, including trenchless, the challenge faced by engineers and municipalities was to select the appropriate rehabilitation, given a certain type of defect, it's location and the amount of infiltration/inflow (I/I), if any. The key element for overcoming this challenge was to obtain complete and accurate information on the defects in sewer mains, manholes, and service laterals, and then to cross reference each individual defect with a suitable rehabilitation technology. Since storm sewers are designed to carry inflow (rain water) and groundwater infiltration is not a major concern, unless it carries soils with it, I/I is not a problem for stormwater utilities. Storm sewers however, like any infrastructure, deteriorate with age and, structural failures occur. In addition, water flowing in (infiltration) through failed joints, cracks and holes, carry the surrounding soil and silt into the pipe, forming voids under the pavement, Without underlying support, the traffic load eventually causes the pavement to break up and collapse. Faced with sometimes costly open cut repairs, including severe social costs (traffic rerouting, temporary business closure, etc.), engineers and stormwater utility owners have looked at alternate "no-dig" repair technologies. Several trenchless technologies applied for sanitary sewer repairs can also be used for repairing storm sewers. A successful repair program relies on an intensive storm sewer system evaluation survey (SSES) to obtain all necessary data for the subsequent rehabilitation phase.

A water distribution system located in a growing residential community north of Dallas/Fort Worth, Texas, was experiencing a higher rate of water leakage and pipe breaks than was considered acceptable. The main breaks appeared to be a result of continued external corrosion. Experience has shown that the frequency of main breaks would likely increase, but the municipal officials were very concerned about the potential disruption that would occur with any replacement or rehabilitation project. A feasibility study demonstrated that a trenchless alternative could be successfully implemented at a lower cost than with conventional open-cut methods. Directional drilling was selected to replace approximately 3,962 m (13,000 ft) of water mains in multiple phases; the first phase included the construction of approximately 1,585 m (5,200 ft) during 2000. This paper describes the results of the technical and economic feasibility study, the detailed design performed, and the construction program implemented.

A variety of ultraviolet light technologies are being applied to the treatment of drinking water and wastewater for disinfection or the destruction of pollutants or disinfection byproducts. These include the use of low pressure, medium pressure, or pulsed lamps and may involve the use of chemical sensitizers or catalysts. The characteristics and efficacy of these different technical approaches are described and compared.

The use of ozone in water treatment plants is expanding rapidly in the United States. Ozone offers excellent disinfection properties (including chlorine-resistant pathogens) and does not form trihalomethanes. Additionally, ozone can be used to achieve or control many other water quality parameters such as color, taste and odor, and inorganic and organic contaminant concentrations. Control of ozone's disinfection byproducts such a bromate (formed in high bromide waters) is required. This presentation will review the synergistic effects of ozone applicable to use in small water treatment plants.

This paper summarizes the expansion of a conventional surface water treatment facility using advanced technologies. The first technology employed is the use of ballasted coagulation/flocculation clarification for preliminary treatment. The second technology involves the use of ultrafiltration membranes. Both of these technologies have recently been utilized throughout the United States in various independent applications. Their joint use in the expansion of the Cass PWSD #7 treatment plant marks the first use of these combined technologies. The preliminary treatment process has provided solid turbidity removal prior to application to the ultrafiltration membrane units. As a result, the operation of the membrane units has been enhanced. This facility has now been operational for approximately one year. During this first year finished water quality has been maintained well below state and federal requirements.

The Stage-1 Disinfectants/Disinfection By-Products (D/DBP) Rule was promulgated in December, 1998. This regulation establishes maximum residual disinfectant levels (MRDLs) for several disinfectants, as well as new or revised maximum contaminant levels (MCLs) for certain DBPs: chlorinated organic DBPs, such as THMs and HAAs, as well as inorganic DBPs. such as bromate and chlorite. Because naturally occurring organic matter (NOM) reacts with chlorine to form DBPs, the D/DBP Rule includes a treatment technique for improving NOM removal. Utilities must achieve a certain level of NOM, or disinfection by-product precursors (DBPPs) removal bv what is termed `enhanced' coagu1ation. The requirements of this regulation (i.e., the MCLs, MRDLs, and enhanced treatment) must be met by both large and small-sized Subpart H systems that use conventional treatment. Many large utilities, especially those which participated in the Information Collection Rule, are already meeting the Stage-1 MCLs for DBPs and the TOC removal requirements of enhanced treatment, or are in the process of making modifications to treatment to achieve compliance. Smaller-sized utilities, however, are typically presented with more challenges to achieving compliance. This paper focuses on DBPP removal by enhanced coagulation, with an emphasis on the challenges faced by smaller utilities, and the tools available to them for complying with the D/DBP Rule. A case study is presented to illustrate the traditional approach to determining enhanced conditions, and the impact of this regulation on small systems. A separate discussion is also provided to introduce an emerging technology for improving precursor removal. This technology is magnetized ion exchange, and it is an adsorption process that can be used by small systems needing to reduce precursors prior to disinfection.

Recent advancements in several freight pipeline technologies have made it feasible to consider using freight pipelines for transporting solid wastes of various types. This paper reviews the state-of-the-art and offers advice on the use of various types of freight pipelines for transporting different types of solid wastes under different conditions. It also describes emerging technologies that show promise for solid waste transport. The use of freight pipelines instead of trucks to transport solid waste has environmental and safety benefits, in addition to cost saving. Freight pipelines should be seriously considered by government and private organizations concerned with solid waste handling and disposal.

The use of no-dig rehabilitation techniques has become of increasing interest and importance over the past two decades in countries and industries with deteriorating pipeline infrastructures. Rehabilitation techniques in general offer pipeline operators a cost-effective alternative to complete pipeline replacement which may be either significantly more costly, or impracticable, or both. The technology has developed in direct response to the changing technical, economic and indeed social issues facing utilities. This paper examines the development and use of two close-fit PE lining techniques developed to meet the needs of the water and gas industries (Rolldown and Subline), and also epoxy resin lining.

Passive biological permeable barriers that can be designed to degrade target contaminants in groundwater to harmless by-products and require almost very . low annual energy or labor input has obvious advantages over conventional pump and treat. This investigation developed and evaluated a biological permeable barrier medium designed to biodegrade 2,4,6 trichlorophenol (TCP) contaminated groundwater to harmless by-products under aerobic conditions. Polyvinyl alcohol (PVA) immobilized cells was selected as the medium for a series of column studies under a variety of operating conditions for 240 days to simulate a passive biological permeable barrier. PVA-immobilized cells were found to be a very good permeable barrier medium with a 100% – 91% TCP removal efficiency at loading up to 0.3–0.6 g L^–1 d^–1, respectively. In this study the removal efficiency of PVA-immobilized cells were tested under shock loads of TCP (>550 mg/L TCP) and deficiency of dissolved oxygen (DO<2 mg/L). PVA-immobilized cells were able to tolerate two 50 hours shock loads of 500 mg/L of TCP and resume their biodegradation activity. PVA-immobilized cells also tolerated two 50 hours of very low DO and continued to biodegrade TCP in the influent. This investigation showed cells entrapped within PVA were protected against high shock loads by immobilization and resumed their biological activity to the steady state in a matter of few days.

Heavy metals (Cd, Cu and Pb) in two simulated contaminated soils were removed by using electrokinetic technology. Soil samples collected from nearby the contaminated sites in Taiwan were examined in the laboratory for soil characteristics and formal distribution. The results showed that the soils contain low to medium energy level forms of metals, such as exchangeable, carbonate and Fe—Mn oxides' metals. Under 8 Volts DC electrification for 10 days, 60% to 95% of Cu and Cd were removed from the soils. It indicated that the electrokinetic process has the potential to remove exchangeable, carbonate and some Fe—Mn oxides' copper and cadmium in the contaminated soils. The high energy level forms of metals, such as organic and some Fe—Mn oxides' copper, cadmium and lead can also be removed from both acidic and basic soils. However, it requires a longer operation period. Among three metals, the highest removal efficiency is Cd, followed by Cu and Pb.

This paper presents the use of burned sludge ash as a soil stabilizing agent. The sludge was burned at 550° C and mixed with three different types of clayey soil at different percentages. A laboratory study consisted of the following tests were carried out on samples treated with burned sludge: Atterberg's Limits, Unconfined Compressive Strength, Standard Proctor Density, and Swelling Pressure tests. It was found that the addition of 7.5% by dry weight of the burned sludge ash will increase the unconfined compressive strength and the maximum dry density, while the addition of 7.5% of the burned sludge by weight of the dry soil minimizes the swelling pressure of the soil. The addition of percentages grater than 7.5% by weight will decrease both the maximum dry density and the unconfined compressive strength. The test results show that this material can be used as a soil stabilizer

A portion of the environmental field thrives on taking toxicological studies, extrapolating human health based risks, and governing the life of certain materials and chemicals. This paper summarizes the science and engineering used to clean up a property contaminated with pentachlorophenol (PCP). The paper discusses statutes and regulations which deal with owner liability, federal authority to respond, and proper disposal of hazardous wastes. The paper also looks at the statistics used to achieve representative sampling, and data quality objectives. The paper also explains how removal action levels were determined, and at what cost. The project demonstrates how science has lead engineers, industry, and governments to spend billions of dollars in environmental clean-up. It is the author's intent to let the audience decide if sound engineering practices were used, and if current practices in the hazardous waste industry are indeed engineered and are up to par with the design and engineering practices used in other fields.

Unbalanced thrust at bends in buried pipelines has historically been resisted by cast in-situ concrete thrust blocks. In recent years methods have been developed that allow the design of buried piping systems without the need for thrust blocks, i.e. pipes and fittings that carry axial thrust and bending moments. Stiff pipes made of isotropic materials behave in a manner, and have enough reserve axial strength, that warrants simplified analytical methods. Because of the low strain levels of such pipes, the effects of displacements and bending stresses can be ignored in many cases. Pipes made of flexible and/or orthotropic materials such as glass fibre reinforced plastics (GRP), however, require more rigorous analysis, to ensure that displacements and stresses are kept within limits. This paper presents a structural analysis method that incorporates the necessary parameters for such a design. The non-linear soil-pipe interaction, both in the lateral and axial directions, is accounted for and the appropriate stiffness matrix for each pipe element is compiled. A solution based on a simple spreadsheet algorithm, is presented.

Crotch-plate design has become an exercise in reading curves and/or meticulously solving equations, rather than providing a design with a substantial understanding of the interaction between crotch-plates and the connecting pipeline. This is a result of technology available in the early 1900 s where the bulk of today's standards originated. Without a substantial understanding of the mechanics involved, the engineer does not have the means to provide a refined design. However, through the use of modern computing, crotch-plate design has become faster, easier and more comprehensive. By the use of curves and equations, Blair and Swanson of the 40 s and 50 s, respectively, have provided a means to conservatively size crotch-plates for many applications. The process typically begins by sizing plates with nomographs; curves based on empirical data obtained from a small diameter pipeline. The designer, if he chooses, may then progress to solving structural determinate equations for the structurally indeterminate crotch-plate system. Unfortunately, as with nomographs, this also only provides a portion of the real picture. However, by using the modern personal computer and commercially available 3-D finite element (FE) software, understanding of structural interaction is greatly improved, calculations are efficient, and refinement is achieved. This method was applied to the 4.3 m (14 ft) fittings of the P-l Pumping Plant at the Diamond Valley Lake located near Hemet, California. The subject analysis method pursues the use of both the 3-D FE and traditional numerical methods, while limiting the use of nomographs. Although FE is the author's choice for designing crotch-plates, the traditional method is maintained due to its reasonable accuracy and availability. Even though stresses and deflections may be obtained through traditional methods, they only provide an understanding of the structural interaction problem allowed by the limiting assumptions of the governing equations. Generally, understanding of the three-dimensional structure is confined to a two-dimensional system. Presented in this paper is an explanation of three-dimensional stresses as they relate to both global and local deflections. Design for plastic behavior is given and shown to be present through traditional methods. A discussion is provided describing why traditional calculations are conservative, and an outline is given describing the pitfalls to avoid when modeling with the 3-D FE method.

Parallel pipelines are becoming more common in urban areas as space within existing roadways becomes limited and as demands exceed existing pipeline capacities. This paper provides a summary of the technical information used to design new pipelines in parallel with existing pipelines. Of primary concern are separation distance, dead and live loads during construction, and failure and subsequent risk of erosion. Sufficient separation distance is required between parallel pipelines to maintain stability of the supporting soil around the existing pipeline and to minimize the potential for cross contamination. During construction, dead and live loads on existing pipelines must be considered when evaluating constructability and estimating the required construction work zone width. Failure of a pipeline and erosion from discharged fluids may undermine adjacent pipelines. A project currently in design is used to illustrate the design of a new pipeline to be constructed parallel to existing pipelines. The location of the new pipeline and required construction width were an important element of the Environmental Impact Report.

An investigation was carried out to utilize different clay minerals to activate the wastewater digested sludge (WWDS) in order to increase and/or control the production of off-gas. The effect of different mixing ratios of the WWDS with clay minerals (kaolinite and montmorillonite) and the pH of the mixture on the sludge degradation have been studied in this work. Different mixing ratios (clay mineral to sludge W_c : W_s) ranged between 10 % and 80 % have been applied in this study. Also different pH values ranged from 5–9 have been investigated. Experimental results indicated that the optimum mixing ratio for kaolinite was 80%, and for montmorillonite was 40%. It was found that the pH value is very important for the control of the quantity and the time of production of the off-gas. These findings can be utilized for commercial use to achieve efficiency and flexibility in the process of off-gas production.

Settling column analyses were performed on mixed liquor from seven AWT and two conventional wastewater treatment facilities. An algorithm was developed relating initial MLSS concentration and unstirred SVI (uSVI) of the mixed liquor to the zone settling velocity (Vs). Statistical analysis of the data using two-tailed paired comparison student-t tests indicated there was no significant difference between uSVI and stirred sludge volume index (sSVI). Examples are presented to illustrate how engineers and operators may utilize a secondary clarifier-operating diagram.

This paper presents three case histories where solid waste landfill settlement monitoring was performed. Based on the settlement monitoring, coefficients of secondary compression due to self-weight and external load were estimated. Finally, uses of these coefficients for long-term settlement estimation and their application to post-closure maintenance and development plans have been presented.

Formal risk assessment is gaining wider acceptance and being used more throughout the pipeline industry. Maintenance and operation budgets are being driven by the need to effectively select and implement projects that reduce system risk, while still meeting company cost:benefit economic models. This refocused engineering assessment approach has driven pipeline operators to use integrated quantitative analyses in their previously empirically driven safety and design programs. The experience gained from this mixed approach can give pipeline design engineers new insight into improved pipeline design techniques that will yield longer-term risk reduction performance. Designs that incorporate risk reduction philosophies will provide a greater level of safety to the public and environment, while enhancing the overall reliability of the pipeline system. If done properly, the incremental cost associated with enhanced pipeline designs that take into consideration risk concerns can be minimal. This paper will present an introduction to a risk assessment modeling technique that has been used in the pipeline industry since 1994 and review design variables that contribute to risk, with specific emphasis on the discussion of new strategies that lead to longer term, lower risk pipeline systems.

The selection of plant species and amendments for the phytoremediation of uranium (U) contaminated soil has been hampered by a lack of information relating the speciation of U in the soil to plant uptake. The goals of the present study were to: 1) provide fundamental information regarding the uptake and translocation of U by plants; 2) utilize that information to improve the phytoextraction of U from contaminated soil. The first goal was achieved by using computer speciation modeling and hydroponic experiments to demonstrate that the uranyl (UO₂²⁺) cation was the U species most readily accumulated in plant shoots. A hydroponic screening experiment was then conducted to identify plants species capable of accumulating the uranyl cation in plant shoots. A soil incubation study addressed the second goal by examining the solubilization of U from contaminated soil by synthetic chelates (HEDTA) and organic acids (citric, oxalic). The results indicated that citric acid solubilized >100 times more U than the other amendments. The results of the hydroponic and soil experiments were then integrated in a pot study in which red beet was grown in U-contaminated soil amended with either citric acid or HEDTA. Citric acid was again highly effective, dramatically increasing shoot U content. In addition to providing fundamental information regarding the form of U taken up by plants, this study also illustrates the importance of basic research to the field of phytoremediation. Based on this information and other studies we have conducted, it should be possible to develop an effective phytoremediation strategy for U-contaminated soils, using citric acid as the principle soil amendment.

In whole-plant laboratory studies, hybrid poplar trees were shown to impact a variety of fate and transport mechanisms for benzene. Laboratory experiments investigated the distribution of the contaminant in the plant tissues, degradation in the soil profile, and volatilization from both the soil and leaf tissues. A new testing system was developed that allowed for rapid testing that is more field-representative than earlier studies. Whole plants were utilized in a reactor design that included both a saturated and a vadose zone. The continuous feed reactors were supplied with a steady influent benzene stream to mimic plume conditions. The presence of the poplar trees enhanced the degradation rate of the benzene, and dramatically decreased the effluent mass of benzene. Benzene was also volatilized from the leaf tissues, providing evidence to the extent of plant enhanced volatilization that has not been previously documented. The observed degradation and removal pathways were a result of active/live trees. Reactors with killed controls did not exhibit the removal seen in the live tree replicates. The soil profile maintained higher degradation rates with the trees present. Causes for the higher degradation rates appeared to be larger microbial populations of benzene degraders and preferable redox conditions in the presence of the poplars. These results combined with previous hydroponic and related field scale studies to provide evidence that phytoremediation has potential for effective, efficient, and environmentally friendly application at benzene contaminated sites, and potentially other contaminated sites with biodegradable organics or VOCs.

A study was conducted to evaluate the nitrification capability of an existing and successfully operated overland flow and wetland wastewater treatment system following a waste stabilization pond for a small town. Seasonal temperature effects on performance were also investigated. The treatment system studied consists of a two-cell waste stabilization pond followed by an overland flow system and a wetland system. The overland flow system consists of two parallel fields (425' x 185' each) (130m x 56m each) where reed canary grass is well established. The wetland system consists of four cells (120' x 105' each) (37m x 33m each), two of which are surface flow type and the other two are sub-surface flow type. The influent and effluent samples were analyzed for BOD₅, suspended solids (SS), pH, temperature, ammonia nitrogen, and nitrate nitrogen. The results of the study indicate that the combined overland flow and wetland system provided excellent treatment of municipal wastewater. The overall average BOD₅ removal by the entire treatment system was about 90.7%. The highest removal was 96.0% and the lowest was 85%. The overall suspended solids removal varied from 41.7 to 99.2% with an average of 88.2%. The ammonia nitrogen removal efficiency of the entire treatment system was 88% which indicates significant ammonia nitrification.

A bench-scale study of biological phosphorus removal (BPR) from primary settled wastewater from the Brookings Municipal Wastewater Treatment Facility (BWWTF) was conducted. The study included a mainstream BPR process in two and three stages. The effect of additional soluble BOD on three-stage BPR process performance was also studied. From the influent total phosphorus concentration of 13.0 mg/L at the existing full-scale RBC-activated sludge facility, primary clarification removed 2.8 mg/L and secondary treatment units removed 5.6 mg/L of phosphorous. An overall phosphorus removal of 66% was observed at the BWWTF during this study period. Effluent soluble total phosphorus (STP) concentrations obtained in the two-stage laboratory BPR processes were above 3.7 mg/L as P and were found comparable to the conventional activated sludge process. The University of Cape Town (UCT) type BPR process resulted in effluent phosphorus concentrations as low as 2.3 mg/L as P. The effluent phosphorus concentrations from both the anaerobic-aerobic process and UCT-type process were not significantly affected by influent phosphorus concentrations. The process with enriched soluble BOD resulted in continuously lower effluent STP at increasing concentrations of sodium acetate. The UCT-type process with enriched soluble BOD resulted in effluent STP as low as 0.5 mg/L as P. For successful BPR operation, the amount of soluble BOD in the influent was found more significant than total BOD₅.

A computer program for the optimal design of wastewater collection was developed. The program consists of two coupled algorithms. The first is for the generation and assessment of all feasible layouts for the excavation volumes only. The second focuses on the optimal hydraulic design of all links in the collection system. The optimization technique used in the latter algorithm utilizes a dynamic programming method that computes velocities, water depths, pipe slopes, and invert elevations. These algorithms are flexible so that the design criteria could be easily modified or changed. The objective cost function includes the costs of the sewers, sewer construction, hydraulic test, and the construction of the manholes. A least-squares regression analysis was employed for the formulation of the objective function. The objective function was restricted by a set of technological and hydraulic constraints including minimum diameters, flow velocities, depth of excavation, and the invert elevations. A sensitivity analysis was performed to test the effect of the various design variables and constraints. The developed methodology shows the benefit of optimization techniques when compared to the conventional design approaches, and great capital cost savings can be achieved.

This paper reviews the design and installation of Concrete Bar-Wrapped Cylinder pipe (C303), a pipe that has served the water industry in the US and Canada for over 50 years. It is a durable pipe, designed as a composite structure combining the tensile strength of steel with the compressive strength and corrosion-inhibiting properties of Portland cement mortar. This pipe is manufactured in accordance with the AWWA Standard C303 and is designed in accordance with AWWA Manual M9. Although the pipe is described as semi-rigid, diameters 610 mm (24 in) and smaller are essentially rigid and require minimal bedding. Larger diameter C-303 depends increasingly on developing supporting strength from the lateral soil pressure.

Estimates have been made of benzene and methyl tertiary butyl either (MTBE) concentrations in the Barton Springs Aquifer that might result from a proposed pipeline petroleum product release. The analysis uses limited and preliminary information from ongoing dye trace studies in the Barton Springs Aquifer. Results indicate benzene concentrations as high as 136,000 ug/L and MTBE concentrations as high as 545,000 ug/L at aquifer discharge locations. Contaminant concentrations are predicted to exceed federal safe drinking water guidelines or limits for up to 233 days. Estimates were developed using available data for high aquifer flow conditions. Peak concentrations would be higher and contaminant discharge duration would be longer during normal and low flow conditions. More conservative assumptions regarding the spill volume and release scenario would also produce higher estimates of benzene and MTBE concentrations, as well as longer periods of time during which concentrations would exceed federal guidelines or limits for safe drinking water.

GeoMedia, a Geographic Information System (GIS), was used to design an irrigation network in eastern Arkansas. The objective of using this geographic information system is to insure that irrigation water can be delivered to each farmland (or tract) and to determine the design flow of each irrigation pipe. To demonstrate the capacity of this GIS, a pilot site was selected in eastern Arkansas. This preliminary investigation showed that the geographic information system is a simple, efficient, and easy to operate. The final implementation of this methodology has been considered for a large-scale application.

A new UK regulatory arsenic standard of 10 μg/l will be introduced in 2003. Severn Trent Water has 17 groundwater sites which will be affected by this legislation and has been undertaking a programme of development work since 1995 to identify the best treatment process. The Company is now in a position to build the treatment plants and this paper describes the development studies which led to the construction of a prototype plant and, following value engineering, the procurement strategy that was used for the remaining 16 sites.

Arsenic occurs in both inorganic and organic forms in water. Although various methods have been adopted to remove inorganic forms of arsenic from drinking water, not much emphasis was given for the removal of orgainc forms of arsenic in drinking water. In the present study column studies were conducted using manganese greensand, iron oxide-coated sand (1 and 2) and ion exchange resins in Fe³⁺ form, to examine the removal of organic arsenic (dimethylarsinic acid) spiked in tap water. Batch studies were conducted with IOCS-2, and the results showed that the organic arsenic adsorption capacity was 8 μg/g. Higher bed volumes (585) and high arsenic removal capacity (5.69 μg/cm³) were achieved with ion exchange resins among all the media studied. Poor performance was observed with manganese greensand and iron oxide coated sand-1 (IOCS-1).

A study was initiated in the City of Regina, Canada to investigate the effect of plumbing material on the drinking water quality. Three rounds of sampling were conducted during November, 1994 to January 1995. Over a hundred residents participated in this study for each of the sampling rounds. Approximately 600 violations of Canadian drinking water guidelines (CDWG) maximum allowable concentration (MAC) levels were observed during the study. Violation of the MAC levels was noted to be the maximum during the first round. The effect of the area of the city on the heavy metal concentration in the drinking water samples was significant. The sampling round or the month of sampling had a significant effect on the heavy metal concentration. The effect of the type of dwelling was not significant on the metal concentration found in the drinking water. Plumbing age and the material of plumbing had a significant effect on the leaching of the heavy metals in the drinking water samples in each of the three rounds.

This paper documents the performance of a subsurface-flow constructed wetlands system during its initial years of operation under variable loading and operating conditions associated with a northern midwestern U.S. climate. The results indicate that effective and sufficient CW seasonal removals of TSS, VSS, CBOD₅, COD, and fecal coliform were achieved. Wastewater temperatures seemed to affect CBOD₅ and COD removal rates. Nitrogen and phosphorus reductions were not as effective and varied seasonally, as well as with wastewater temperature. The addition of a sand filter, to aid in further nitrification and disinfection following CW treatment, markedly improved the performance of the wetlands system. After a few years of operation, the remarkable performance of the CW system was dampened by apparent clogging and subsequent eruption of wastewater at the head-end of the treatment cells. While clogging was partially caused by biomass build-up in the wetlands substrate, visual observations suggest that excessive vegetation coupled with relaxed maintenance may also be responsible for clogging.

Water transmission system is one of the lifeline systems, which is of significant importance to safety, health and normal life of a community. Therefore, the consideration of the serviceability of water systems under an expected earthquake is quite necessary. The branched water network systems were analyzed by the continuity condition of flow, and pipe failure mode condition. The objective was to increase the "factor of safety" or reduce the "vulnerability" of water network systems by selecting the pipe sizes under seismic loading, which the axial strain mode of pipe failure was only considered here. The planning management model was used to illustrate for branched water network systems, which formulated as a linear model. Several simple hypothetical examples were illustrated here.

This paper describes the Value Engineering (VE) process and its application to pipeline projects. Eight different projects to which VE was applied were studied. The unique characteristics of these pipeline VE studies are described, along with the benefits gained through VE. The typical savings possible from the application of VE and the areas where savings can be expected on a pipeline VE study are examined.