Operational Ranges for Suction Lysimeters

Four questions relative to suction lysimeter performance have been raised by operators of land treatment systems. These questions deal with plugging of the porous segments of the lysimeters, soil suction operational ranges, adsorption onto and screening by the materials comprising the various lysimeter parts, and loss of volatile organics under negative pressures. This article first describes the physical operation of a lysimeter, the characteristics of the lysimeters tested (high- and low-flow lysimeters with porous ceramic cups and lysimeters with porous PTFE (polytetrafluo-roethylene) cups, and procedures followed in preparing them for testing. The results of experiments dealing with the first two questions plugging and operational ranges are then discussed. It was found that the intake rate of suction lysimeters placed in the vadose zone, in most types of soils, will initially drop off rapidly, but will stabilize after about 15 liters of moisture have been drawn through the porous cups. Packing a crystalline silica flour slurry around the cups of PTFE lysimeters negates most of the plugging associated with finer particles in soils. The effective operating range of ceramic lysimeters is between 0 and 60 centibars of suction independent of the use of silica flour. The operating range of PTFE lysimeters without silica flour is extremely narrow, but with the use of silica flour is extended to about 7 centibars of suction. The testing program indicates that all lysimeters should be checked for leaks using pressure techniques before field installation and that lysimeters have "dead" spaces, or reservoirs of from 34 to 80 mL of moisture that cannot be extracted from the cups, which must be taken into account when determining moisture collection rates. Information gathered in the test program is planned for inclusion in an EPA guidance document entitled "Unsaturated Zone Monitoring at Hazardous Waste Land Treatment Units."     

Beyond BTEX

"It's definitely not a time to become complacent with our current understanding of contaminant fate and transport processes."
"In the coming year, we are going to solicit short one- to two-page field Innovation Notes in GWMR."     

DNAPL — Stop the Madness

"The EPA decided that showing the presence of DNAPL would prove that cleanup to non-detect was improbable, and that a new end point could be selected."
"The only thing that really matters is the total mass of from the natural attenuation."     

The Challenge of Ground Water Quality Monitoring

"Valuable information pertaining to contaminant sources, contaminants, and ground water quality was derived using the state-supplied data."     

A multiscale electrical survey of a lateritic soil system in the rain forest of Cameroon

Resistivity investigations were carried out on an elementary watershed in SW Cameroon, firstly to assess the applicability of direct-current (DC) resistivity methods to solve various pedological problems in intertropical regions, and subsequently to determine the relationships between electrical resistivities and pedological properties of lateritic soil systems. The survey included measurements in pits with a small Wenner fixed-spacing array (SWA), vertical electrical soundings (VES) and vertical electrical “quick soundings” (VEQS) both using the Schlumberger configuration. The VES data were interpreted using a conventional multilayer inversion program to obtain best-fit models. Constraints to the interpretation of these data were provided by SWA and pedological information from existing observation pits. The results of the interpretation reveal five distinct geoelectrical layers overlying a resistive bedrock. The first is a thin organo-mineral upper layer with low resistivities in the range 250–450 Ωm. The second layer corresponds to micro-aggregated clayey materials and is more resistive (1300–1800 Ωm). The third represents the main part of ferruginous materials and is even more resistive (2000–4500 Ωm). The fourth corresponds to unsaturated saprolite and the last to saturated saprolite (ground water) with resistivities ranging from 800 to 1500 Ωm and from 150 to 250 Ωm, respectively. Estimates of soil volumes for the entire study area were obtained from VEQS interpretations. Most of the soil cover corresponds to saprolite (74%, being saturated by ground water), while topsoil and ferruginous materials represent 14 and 12%, respectively. Finally, geophysical results based upon 1-D inversion provide a satisfactory approximation of the various lateritic components' 3-D geometry over the watershed. The study provides original quantitative results concerning the behaviour of intertropical soil systems as well as some geomorphological keys for soil mapping at a regional scale.     

International borders, ground water flow, and hydroschizophrenia

A substantial body of research has been conducted on transboundary water, transboundary water law, and the mitigation of transboundary water conflict. However, most of this work has focused primarily on surface water supplies. While it is well understood that aquifers cross international boundaries and that the base flow of international river systems is often derived in part from ground water, transboundary ground water and surface water systems are usually managed under different regimes, resulting in what has been described as "hydroschizophrenia." Adding to the problem, the hydrologic relationships between surface and ground water supplies are only known at a reconnaissance level in even the most studied international basins, and thus even basic questions regarding the territorial sovereignty of ground water resources often remain unaddressed or even unasked. Despite the tensions inherent in the international setting, riparian nations have shown tremendous creativity in approaching regional development, often through preventive diplomacy, and the creation of "baskets of benefits," which allow for positive-sum, integrative allocations of joint gains. In contrast to the notion of imminent water wars, the history of hydropolitical relations worldwide has been overwhelmingly cooperative. Limited ground water management in the international arena, coupled with the fact that few states or countries regulate the use of ground water, begs the question: will international borders serve as boundaries for increased "flows" of hydrologic information and communication to maintain strategic aquifers, or will increased competition for shared ground water resources lead to the potential loss of strategic aquifers and "no flows" for both ground water users?     

Other Types of Contamination

"Hazardous levels of methane in the subsurface occur at numerous locations across the United States."     

试论"十五"期间我国地震地下流体前兆台网的优化与建设问题

根据我国地震地下流体前兆台网的现状、“九五”台站建设取得的进展与存在的问题,提出“十五”期间有关台网优化与建设方面的如下工作建议：（1）优化现有的台网;（2）完善与推广数字化观测技术,力争使经过数字化改造的台站数量由100个扩展到300个,实现数字化观测的台项由300个增加到10000个,基本实现我国流体前兆观测技术的现代化;（3）建设以地震监测与预测研究为目的前兆实验场。（4）建成地下流体学科技术中心;（5）建设重大工程的地震安全性监测系统。     

EPA's CLEANUP 2000: Reforms to the RCRA Corrective Action Program

"EPA has initiated CLEANUP 2000, which includes a number of reforms to the RCRA Corrective Action Program to help increase the pace of cleanups."     

Evidence for MTBE in Heating Oil

"Contamination of heating oil with MTBE could result in increasing the environmental impact of subsurface heating oil releases."     

Comments on EPA Guidance for Ground Water Studies

"The panel provided good, solid, interdisciplinary advice on a variety of challenging, state-of-the-art issues."     

Design for a Packer/Vacuum Slug Test System for Estimating Hydraulic Conductivity in Wells with LNAPLs, Casing Leaks, or Water Tables Intersecting the Screens

"Results indicate that the packer/vacuum system is an adequate method for obtaining values of hydraulic conductivity."     

REFLECTIONS ON WATER RESOURCES RESEARCH

"Fortunately, this nation is well endowed with water. We get enough precipitation every year to cover the whole country with water 30 inches deep."     

Identifying Synergy Between Remedial Strategies and Land Reuse

"Today the environmental professional teams with the developer to use remedial technologies and approaches that complement planned land use and, conversely, use land in a fashion that accommodates environmental site conditions."     

Caution Against Interpreting Gasoline Release Dates Based on BTEX Ratios in Ground Water

"Traces of MTBE in ground water (>10 ppb) do not necessarily indicate recent gasoline contamination."     

Successful Evaluation of EPA's New Screening Model

"A successful test of such a conservative screening tool would predict concentrations of pesticides that are in the upper 95 to 99% confidence interval of appropriate monitoring results."     

Comment on "Caution Against Interpreting Gasoline Release Dates Based on BTEX Ratios in Ground Water," by Pedro J.J. Alvarez, Richard C. Heathcote, and Susan E. Powers, Fall 1998 Ground Water Monitoring & Remediation, v. 18, no. 4: 69-76.

"Our experience shows that BTEX ratios, when used cautiously, often provide valuable information on the age of gasoline fuel release."     

基于WCF和Web架构构建分布式前兆数据分析处理系统

现有前兆数据分析处理系统多以 C/S 模式应用为主,提出一种基于 Windows 通信基础（WCF）、B/S模式应用的实现技术途径,可以实现前兆数据在线分析处理功能,并构建原型实验程序SODEws。此方案实现的B/S应用适用于各种计算机终端,也可用于支持Web浏览器的移动设备,并可实现基于云计算技术平台部署。     

History of the Sole Source Aquifer Program: A Community-Based Approach for Protecting Aquifers Used for Drinking Water Supply

The Sole Source Aquifer Program has helped prevent contamination of many community drinking water supplies. If an aquifer supplies the sole or principal source of a community's drinking water, a local ground water user may petition the Environmental Protection Agency (EPA) under the Safe Drinking Water Act for its designation and protection as a "sole source aquifer." Since 1974, residents and officials of 65 communities and multi-community areas have petitioned and received assistance from the EPA to prevent contamination of their local ground water source of drinking water. This designation means that EPA may review federal financially assisted projects to determine if they would contaminate the aquifer and cause a public health hazard. If they could cause contamination, EPA can request that the project be modified or stopped. The significance of this program in terms of population served and funds affected has been substantial, indicating the Sole Source Aquifer Program has been an important local tool for protecting ground water used as a source of drinking water. Information is given on three different examples of sole source aquifer designations protected under this program: the New Jersey Coastal Plain Aquifer System, the Great Miami River Buried Valley Aquifer System (Ohio), and the Eastern Snake River Plain Aquifer (Idaho), serving populations of 543,000, 921,000, and 275,000, respectively. In all three examples, preventing ground water contamination through the Sole Source Aquifer Program has protected the community drinking water supply.