Anthony N. Tafuri

LID-BMPs planning for urban runoff control and the case study in China

Low Impact Development Best Management Practices (LID-BMPs) have in recent years received much recognition as cost-effective measures for mitigating urban runoff impacts. In the present paper, a procedure for LID-BMPs planning and analysis using a comprehensive decision support tool was proposed. A case study was conducted to the planning of an LID-BMPs implementation effort at a college campus in Foshan, Guangdong Province, China. By examining information obtained, potential LID-BMPs were first selected. SUSTAIN was then used to analyze four runoff control scenarios, namely: pre-development scenario; basic scenario (existing campus development plan without BMP control); Scenario 1 (least-cost BMPs implementation); and, Scenario 2 (maximized BMPs performance). A sensitivity analysis was also performed to assess the impact of the hydrologic and water quality parameters. The optimal solution for each of the two LID-BMPs scenarios was obtained by using the non-dominated sorting genetic algorithm-II (NSGA-II). Finally, the cost-effectiveness of the LID-BMPs implementation scenarios was examined by determining the incremental cost for a unit improvement of control.

Wastewater collection system infrastructure research needs in the USA

Many of the wastewater collection systems in the USA were developed in the early part of the last century. Maintenance, retrofits, and rehabilitations since then have resulted in patchwork systems consisting of technologies from different eras. More advanced and cost-effective methods to properly rehabilitate these systems must be considered to guarantee sustainability into the future. Achieving sustainable development presents a challenge to deliver new and innovative infrastructure and facilities needed to serve society while protecting the environment. In the context of this paper, sustainable development would provide new and improved solutions to existing and emerging problems associated with wastewater collection system infrastructure. Such solutions would, for example, include consideration of innovative approaches and practices for identifying and rehabilitating problems in existing systems and ways of preventing these problems in new construction. The paper focuses on technical issues and research needs in three major areas: (1) assessment of system integrity; (2) operation, maintenance, and rehabilitation; and (3) new construction. Many of the issues and needs discussed were identified at a USEPA sponsored experts workshop on infrastructure problems associated with wastewater collection systems.

Chemical oxidation treatment of petroleum contaminated soil using Fenton's reagent

Abstract Fentons reagent, a strong oxidant, was evaluated for suitability to treat soils contaminated with 2‐methylnaphthalene (an aromatic compound), n‐hexdecane (an aliphatic compound) and diesel fuel (a complicated hydrocarbon mixture). Laboratory‐scale results show that Fentons reagent reacts rapidly with these materials in soil, and will completely mineralize them if enough hydrogen peroxide is added. The effectiveness of the reaction at neutral pH indicates that it should be easier and more cost‐effective to apply this technology since no pH adjustment is required prior to soil treatment. Further investigation is required to identify the reaction mechanisms and optimize the parameters to attain the most cost‐effective full scale application of this technology.

Rehabilitation of Aging Water Infrastructure Systems: Key Challenges and Issues

AbstractPresented in this paper are the results of a state-of-the-practice survey on the rehabilitation of water distribution and wastewater collection systems. The survey identified several needs, including the need for rational and common design approaches for rehabilitation systems, quality assurance/quality control procedures and acceptance testing during installation of rehabilitation systems, and decision support tools for choosing rehabilitation/rehabilitation systems versus replacement. Discussed are separate issues for water and wastewater systems in terms of drivers for increased rehabilitation efforts and problems typically encountered. Also examined are the major technologies currently in use and the major issues and key challenges faced in terms of speeding rehabilitation efforts and documenting/improving the performance of the technologies used.

Treatability aspects of urban stormwater stressors

Pollution from diffuse sources (pollution from contaminants picked up and carried into surface waters by stormwater runoff) has been identified as a significant source of water quality problems in the U.S. scientists and engineers continue to seek solutions that will allow them to optimize existing technologies and develop new ones that will provide the best possible protection to people, wildlife, and the environment. This paper addresses the various pollutants or stressors in urban stormwater, including flow (shear force), pathogens, suspended solids/sediment, toxicants (organic and metals), nutrients, oxygen demanding substances, and coarse solids. A broad overview of the pollutants removed and the removal mechanisms by and of conventional best management practices (BMPs) is also presented. The principal treatment mechanisms of conventional wet ponds, vegetative swales/buffer strips, and wetlands are sedimentation and filtration. These mechanisms have the capability to remove significant amounts of suspended solids or particulate matter and are a vital component of strategies to reduce pollutant loads to receiving waters. In addition, because most of the nation’s receiving water violations are caused by pathogen indicator bacteria, it is of utmost importance that research efforts address this problem. Further research is also needed on the treatment of emerging contaminants in BMPs and on the costs and affects of maintenance and maintenance schedules on the long-term performance of BMPs.

State of technology for renewal of sewer force mains

This paper presents the results of a review of the state of technology for renewal of force mains. Force mains are critical components of many sewer collection systems with significant environmental and cost consequences for failure. The review identified several needs, including the need for rational and common design approaches for rehabilitation systems, quality assurance/quality control procedures, and better practices for operation and maintenance. The difficulty in assessing the condition of sewer force mains, leaving many owners with questions about the integrity of their systems, and the limited amount of technologies available for renewing a deteriorated main, has limited the amount of renewal work in the past. Most of the renewal activity has involved complete replacement of the force main. As the nations force mains age further, greater emphasis must be placed on finding cost-effective ways to renew these critical assets. Fortunately, new products and technologies are now emerging for condition assessment, as well as rehabilitation. Some newer methods developed for gravity sewers and water distribution systems are being adapted for use in force main rehabilitation but design and performance data gaps remain to be filled.

Pressure and temperature fluctuations in underground storage tank pipelines containing gasoline

Abstract A common method of detecting a small leak in a pressurized underground storage tank pipeline system containing petroleum is to monitor the pressure in the line. This paper presents theoretical models to predict the pressure changes associated with leaks and product temperature changes in pressurized pipelines. These models have been validated in experiments at retail petroleum facilities and the EPAs UST Test Apparatus. A heat conduction model is used to estimate the waiting period prior to the beginning of the test that is long enough to allow the product temperature changes to be negligibly small, and an exponential pressure-decay model is used to estimate the test duration that allows the pressure drop associated with small leaks to exceed the threshold. The results suggest that a test duration of 15 to 60 min is required to detect leaks as small as 0·1 gal/h and a waiting period of up to 6 to 12 h is required for the temperature changes in a 2-inch diameter pipeline to be negligible after the last dispensing of product through the line.

Innovative Stormwater Treatment Implementation at Parking Lot in China

Xikeng Reservoir is one of the major water supply reservoirs in Shenzhen. The water quality of Xikeng Reservoir has been poor, with much of the pollution coming from nonpoint sources. An innovative low impact development type of BMP called the BioBox was used at the Administration Building parking lot location, as a research site and demonstration project to show how small alterations to parking lot designs can dramatically decrease pollutant loads. Manual samples were collected during storm events and analyzed for total suspended solids (TSS); five-day biochemical oxygen demand (BOD5); ammonia nitrogen (NH3-N), and total phosphorus (TP). In summary, the ranges of removal rates of the BioBox are: TSS 70% - 90%; BOD5 20% - 50%, and ammonia and phosphorus 30% - 70%. The BioBox system effectively reduced the concentrations of pollutants in the parking lot runoff.

Role of Stream Restoration on In-Stream Water Quality in an Urban Watershed-A Case Study

This study addresses the effectiveness of stream bank and channel restoration techniques on improving benthic macroinvertebrate indices and in-stream water quality within an urban watershed. The project involved monitoring before and after restoration of 1,800 linear feet of degraded stream channel in the North Fork of Accotink Creek in the City of Fairfax, Virginia. Restoration, which was completed in June 2006, included installation of native plant materials along the stream and bioengineering structures to stabilize the stream channel and bank. These actions were intended to restore the stream channel to a stable condition, thereby reducing stream bank erosion and sediment loads in the stream. In-stream samples were collected and analyzed for physical, chemical, and biological (macroinvertebrates, bacterial indicators) parameters to document the changes in stream quality as a result of the restoration. The preliminary results of the sampling and monitoring are summarized in the paper.

Evaluation of volumetric leak detection systems for large underground tanks

Abstract The performance standard for tank tightness testing established by the U.S. Environmental Protection Agency (EPA) regulation requires that the systems used to test underground storage tanks be able to detect leaks as small as 0.38 L/h (0.1 gal/h) with a probability of detection of 0.95 and a probability of false alarm of 0.05. This standard was developed to address tanks nominally 30,000 to 38,000 L (8,000 to 10,00O gal) in capacity or less, but also applies to tanks as large as 190,000 L (50,000 gal). The accuracy of detecting leaks in tanks as large as 190,000 L (50,000 gal) is not well known, and very little data from which to make an assessment are available. To meet EPAs regulatory standards for tank tightness testing of petroleum fuel tanks, volumetric leak detection systems must be able to accurately compensate for thermally induced volume changes in the stored fuel. A field study was done to investigate the magnitude of these volume changes. Three 24-h experiments were conducted in two partially filled, 190,000-L (50,000-gal) tanks in upstate New York during late August 1990; product was either added to or removed from the tank to initiate each experiment. The study showed that the procedures used to compensate for the thermally induced volume changes that occur during a tightness test performed on small tanks are not adequate for tanks as large as 190,000 L (50,000 gal). The volume of product in such tanks is large enough to cause significant errors in the estimates of the thermally induced volume changes required for compensation; these errors stem from the presence of horizontal and vertical gradients in the rate of change of temperature. In smaller tanks, the average rate of change of volume due to horizontal gradients is negligible, and a single vertical array of five temperature sensors is sufficient to compensate for the effects of thermal expansion of the product in a 1- to 2-h test. In larger tanks, however, a single array of temperature sensors does not suffice unless certain conditions are met. First, the number of sensors must be increased to at least 10 to ensure that the vertical gradients are accurately measured. Second, an adequate time (at least 24 h) must be allowed for the horizontal gradients to dissipate. Third, the duration of a test must be increased to at least 4 h so that the instrumentation and ambient volume fluctuations can be averaged. Fourth, the average rate of change of temperature in any one layer or in the tank as a whole must be small enough to allow accurate temperature compensation. Finally, an accurate experimental estimate of the constants necessary for converting level and temperature changes to volume must be made. Based on these experiments, a procedure has been developed for temperature compensation in tanks with capacities of 190,000 L (50,000 gal).