U.S. Army Corps Of Engineers Research Articles

Design considerations for in-situ capping of contaminated sediments

In-Situ Capping (ISC) is defined as the placement of a subaqueous covering or cap of clean or suitable isolating material over an in-situ deposit of contaminated sediment. ISC is a potentially economical and effective approach for remediation of contaminated sediment. A number of sites have been remediated by in-situ capping operations worldwide. The U.S. Army Corps of Engineers (USACE) has developed detailed guidelines for planning, designing, constructing, and monitoring in-situ capping projects for the United States Environmental Protection Agency (USEPA). This paper briefly describes the major aspects of in-situ capping as an option and provides a summary of recent case studies.

Corps Fails to Consider Alternatives

Marion, Illinois, and the Lake of Egypt Water District both wanted more water. Each had a reservoir supply of marginal quality. The city proposed to solve both problems in one stroke by establishing a new reservoir created through a dam over Sugar Creek. A 20‐in.‐ (0.5‐m‐) diameter pipeline would run the water to Marion which, in turn, would sell some of that water to the district. The proposed project fell under federal jurisdiction because Sugar Creek was navigable. Thus, it was necessary for the US Army Corps of Engineers to issue a permit. In its environmental impact statement, the Corps confined the analysis to single‐source alternatives. The Corps issued a permit, which was challenged in this lawsuit. The trial court upheld the Corps. The appellate court noted that the Corps never studied whether the single‐source idea was the best, or even a good, idea. According to the court, this may well be the best solution to the water shortages of Marion and the water district, but the Corps erred in accepting this parameter as a given. Thus, the court concluded that the Corps defined an impermissibly narrow purpose for the contemplated project and failed to examine the full range of reasonable alternatives. The trial court decision was reversed.

Design considerations for in-situ capping of contaminated sediments

In-Situ Capping (ISC) is defined as the placement of a subaqueous covering or cap of clean or suitable isolating material over an in-situ deposit of contaminated sediment. ISC is a potentially economical and effective approach for remediation of contaminated sediment. A number of sites have been remediated by in-situ capping operations worldwide. The U.S. Army Corps of Engineers (USACE) has developed detailed guidelines for planning, designing, constructing, and monitoring in-situ capping projects for the United States Environmental Protection Agency (USEPA). This paper briefly describes the major aspects of in-situ capping as an option and provides a summary of recent case studies.

Coconut Farmer Must Restore Wetlands

In 1980, Parks B. Banks bought three lots in Big Pine Key, Florida. He began bulldozing two lots and covering them with fill. He continued this until 1983, when he planted coconut trees on the filled lots and built a house on the third. In March 1983, the US Army Corps of Engineers advised Banks that parts of two lots were wetlands and the discharge of fill materials was unlawful under the Clean Water Act (CWA). Banks continued to discharge fill without a permit and entered into no negotiations for a restoration plan. In 1988, Banks bought two more lots and again converted them to coconut farms. In December 1991, the government sued Banks, seeking an injunction against further discharges, restoration of the wetlands to their undisturbed condition, and a civil penalty. The trial court found that Banks had violated the CWA.

Remediation Technologies Screening Matrix and Reference Guide: Version III

AbstractThe U. S. Army Environmental Center (USAEC) is leading an effort to update the Remediation Technologies Screening Matrix and Reference Guide, Third Edition under the auspices of the Federal Remediation Technologies Roundtable (FRTR). Its purpose is to create a comprehensive “Remediation Technologies Yellow Pages” for use by those responsible for environmental cleanup. The Guide is being produced as a multiagency cooperative effort published under the FRTR. Members of this effort include USAEC, the U. S. Army Corps of Engineers (USACE), the Naval Facilities Engineering Service Center (NFESC), the Air Force Center for Environmental Excellence (AFCEE), the Environmental Protection Agency (EPA), the Department of Energy (DOE), the Department of the Interior (DOI), and the Interstate Technologies Regulation Cooperative (ITRC). This article provides a comprehensive look at environmental technology information provided in the electronic user‐defined Remediation Technologies Screening Matrix and Reference Guide.

Stage adjustment in the Lower Mississippi River, USA

This study documents the stage adjustments in the Lower Mississippi River during the pre-cut-off (1880s–1930s), and post-cut-off (1943–1994) periods. The study reach extends from Columbus, Kentucky, just downstream of Cairo, Illinois, to Natchez, Mississippi, a distance of about 970 km. The analysis shows that the majority of the pre-cut-off study reach was not undergoing any significant system instability such as channel aggradation or degradation, and, therefore can be considered to have been in a state of dynamic equilibrium during this period. However, the analysis did show that the upper portion of the study reach in the vicinity of Columbus was undergoing a significant aggradational trend during this period. Specific gauge records and peak stage–peak discharge plots for the time period 1950–1994 were analysed to document stage adjustments and to divide the river into the following seven reaches based on observed stability: Columbus to New Madrid (dynamic equilibrium); New Madrid to Fulton (transitional/dynamic equilibrium); Fulton to Sunflower (degradational); Sunflower to Rosedale (transitional); Rosedale to Lake Providence (dynamic equilibrium); Lake Providence to Vicksburg (transitional); and Vicksburg to Natchez (aggradational). Thus, the entire Mississippi River, between Natchez and Columbus is responding in a manner similar to the response of a stream to a single cut-off as described by Lane (1947). Recognition of this evolutionary trend is a first step in developing a comprehensive understanding of this complex system, and will help the engineers and scientists of the US Army Corps of Engineers to develop management strategies for the Mississippi River in the long and short term. © 1997 John Wiley & Sons, Ltd.

Loads for Fatigue Life Assessment of Gates at Navigation Locks

The U.S. inland navigation infrastructure is deteriorating primarily due to the aging of its components and the operation at near to full capacity of the system’s structures. Gates at navigation locks play an integral part in keeping navigation traffic continuously moving, and their reliability is essential to the navigation infrastructure. Assessments of fatigue reliability as a function of time for existing gates at navigation locks require knowledge of loading cycles. This assessment can contribute to the economic evaluation of the remaining fatigue life of critical fatigue details in gates. The accuracy of this assessment depends in part on the accuracy of the loading cycles used in the reliability analysis. Water elevations from hydraulic records were used to compute water-head differentials on the miter gates. Loading or hardware cycles were obtained from the U.S. Army Corps of Engineers (USACE) lock performance monitoring system (LPMS) and were then combined with head differential to obtain loading histograms for the gates. These histograms are needed to successfully perform fatigue reliability analyses. A probabilistic model was also developed for predicting the number of loading or hardware cycles for the gates. This paper includes an example to demonstrate the suggested methods and models for fatigue reliability assessment.

Loss in Serviceability of Pavements Due to Expansive Clay Subgrades

In Irbid City, Jordan, soil tests and pavement evaluations have shown that expansion of clay subgrade is a predominant problem, especially in the absence of effective drainage systems. Forty-one pavement sections from different parts of Irbid City were examined and tested. The Pavement Condition Index (PCI), as described by the US Army Corps of Engineers in the pavement evaluation system PAVER, was utilized in this study. This objective evaluation procedure depends on measuring the severity and density of every single distress observed. Physical and engineering properties were obtained from laboratory testing for the subgrade soil at each pavement section, including: Atterberg Limits, compaction characteristics, field density, natural water content, free swell, and unconfined compressive strength. The effect of soil properties on pavement conditions were investigated and the soil parameters that affect pavement deterioration were identified. Empirical regression models that correlate the loss in Pavement Condition Index (PCI) to soil properties were developed. (A)

Reliability Analysis in Support of Risk Assessment for Hydroelectric Generating Stations

In work sponsored by the U.S. Army Corps of Engineers (USACE), Pacific Northwest Laboratory (PNL), Richland, Wash., has performed a frequency analysis regarding the nonroutine closure of water flow through the turbines of powerhouses along the Columbia and Snake Rivers. The analysis involved developing a frequency analysis model capable of producing frequency profiles of overspeed and flooding events as a function of time and the associated component importance rankings. Data regarding hydropower equipment failures from a previous study were used to estimate component failure rates within the model. The present paper summarizes the model development and quantification, and calculation of component importance measures. The results of this analysis can be used as input to further analyses to evaluate economic consequences of overspeed and flooding events and to provide policy recommendations for operations of hydroelectric generating stations.

Remediation of Hazardous-Waste Sites by New England Division of U.S. Army Corps of Engineers

The U.S. Army Corps of Engineers (USACE) New England Division (NED) remediates hazardous-waste sites for the U.S. Environmental Protection Agency's (EPA) Superfund Program and the Department of Defense. In fiscal year 1996 (October 1995–September 1996), over $115,000,000 was expended on work associated with 19 Superfund sites, Army facilities at Fort Devens and the Materials Technology Laboratory (MTL) in Watertown, Mass., as well as numerous formally used defense sites throughout New England. Noteworthy projects include the Baird and McGuire Superfund site in Holbrook, Mass., where contaminated soil is being excavated and incinerated on-site, and the Raymark Superfund site in Stratford, Conn., where 13 acres of industrial buildings were demolished with the site now being capped. NED expects that over $100,000,000 will be expended in fiscal year 1997 as work continues at Baird and McGuire, Raymark, Fort Devens, and the Army's MTL. NED also expects to begin work on the Estuary, Lower Habor/Bay portion of t...

Expected Probability and Annual Damage Estimators

Controversy continues over the relative merits of traditional frequency estimators and the “expected probability” estimator of flood risk that incorporates an adjustment for parameter uncertainty. Both have solid theoretical motivation, but address different concerns. The description of hydrologic risk and uncertainty provided by new risk and uncertainty procedures adopted by the U.S. Army Corps of Engineers, and risk-based design procedures developed by others, are shown to be equivalent to the expected probability model in simple cases. A 1995 National Research Council (NRC) report recommended against use of the expected probability model for evaluating expected annual damages and the probability of flooding; in particular, the NRC analysis and the 1989 Arnell analysis demonstrated that expected probability estimators yield risk and damage estimators that generally have large positive biases. Historical arguments and related issues are reviewed. Resolution of this controversy and success of the new U.S. Army Corps of Engineers (USACE) risk and uncertainty procedures require a clear framework for understanding what is meant by risk, variability, and uncertainty. Such risk analyses can better represent a community's vulnerability to flooding and the large uncertainty in estimates of expected damages and residual flood risk.

Estimating Expected Annual Damage for Levee Retrofits

The U.S. Army Corps of Engineers (USACE) has instituted a new analysis methodology for estimating the expected annual damage (EAD) and resulting economic benefits accruing to proposed flood damage-reduction projects. Although the methodology is new, it still, in effect, uses expected probability to estimate the frequency of flooding and EAD. The National Research Council (NRC) in a review of USACE's study of the American River levees stated that the use of expected probability results in significantly biased estimates of EAD. An alternative damage model to that proposed by NRC is used to show that expected probability leads to an unbiased estimate of EAD. The damage model proposed requires that an unbiased estimate of damage results when applied to many projects. A simulation study demonstrates that EAD estimated with expected probability is unbiased, whereas the NRC's recommended estimator is biased.

Integration of US Army Corps of Engineers' Time-Series Data Management System with Continuous SWMM Modeling

Of the computer applications currently widely used in civil engineering, hydrological modelling has been mostly restricted to discrete events. However, with im…

Hydrogeology of the Lower Mississippi Valley as related to the work of Harold N. Fisk

Principally concerned with the evolution of the Lower Mississippi Valley (LMV), the Fisk (1944) investigation provided one of the first descriptions of the stratigraphic and structural framework of the region. The study provided new data for hydrogeological studies by state and federal agencies. The Fisk report was the basic reference for one of the earliest studies of a complex regional aquifer system — the Mississippi embayment project. Begun by the US Geological Survey (USGS) in 1957, the study covered the Lower Mississippi Region north of the 32nd parallel. A study of ground water in the alluvium in the upper and central part of the region was completed by the US Army Corps of Engineers in 1964 (Krinitzsky and Wire, 1964). A study, completed in 1970 by the USGS for the Mississippi River Commission (MRC) as part of a plan to export water to west Texas and New Mexico, assessed the availability of fresh ground water in the entire Lower Mississippi Region (Boswell, 1970). Some results of this study were included in Appendix C of the Lower Mississippi Region Comprehensive Study Coordinating Committee (1974). During the last 20 years, hundreds of hydrogeological studies have been made in the region, and several computer models of aquifer systems have evolved. The USGS Regional Aquifer System Analysis (RASA) Program included the region in two models: the Mississippi embayment aquifer system and the Gulf Coast regional aquifer system. RASA models establish a geological, hydrological, and geochemical database for use in regional and local development and in the management of ground-water resources. The Mississippi embayment study unit of the National Water Quality Assessment Program is currently underway. Continuing hydrogeological studies are needed to assess in more detail the hydrogeology of all aquifers in the region. The vast alluvial aquifer system is of special importance because it is the largest ground-water reservoir in the region, and it is the most susceptible to contamination and the effects of mismanagement.

The response of the Lower Mississippi River to river engineering

An examination of the response of the Lower Mississippi River (LMR) to a variety of engineering activities is presented through the discussion of: (a) a brief history of engineering investigations and activities on the LMR; (b) the impact of artificial cutoffs on the channel geometry and water surface profiles of adjacent reaches; (c) the impact of channel alignment activities on channel morphology; and (d) the apparent impact of all of the LMR engineering activities on sediment dynamics in the channel. Investigations by many agencies reflect over 150 years of study of the hydraulics and hydrology of the LMR, which have contributed significantly to our understanding of large alluvial rivers. In an effort to provide for flood control and navigation on the largest river in North America, private landowners and the US Army Corps of Engineers have performed a wide range of river engineering activities, including construction of levees, floodways, artificial cutoffs, bank revetment, training dikes, dredging, channel alignment, and reservoirs on the major tributaries. This unprecedented program of river engineering activities on the river during the last 100 years has resulted in the evolution of a freely meandering alluvial river to a highly trained and confined meandering channel. The LMR has increased its overall gradient and average top-bank width and generally increased its channel depth. The immediate response of the river to increased gradient as a result of the construction of artificial cutoffs was dampened in some locations by local geological controls. Examination of the trends in sediment dynamics of the LMR reveals that the suspended load of the river has decreased during the 20th century. Conversely, a trend in the bed load transport in the channel for the years 1930 and 1989 cannot be determined with confidence because of the difficulty in acquiring representative samples. The highly trained river now responds to channel forming flows by attempting to build mid-channel bars rather than natural cutoffs of meanders. The LMR should maintain a relatively stable plan form in the intermediate future, barring a very large and unprecedented flood. The river will continue to adjust its channel geometry and its local gradients as a response to variations in significant discharges. Continued channel maintenance and occasional dredging will insure the present state of sediment and water transport efficiency.

Overview of Corps of Engineers waste containment activities involving geosynthetics

Containment has proven to be a viable option for remediating many hazardous waste sites. The US Army Corps of Engineers (COE) has been involved in the design and/or construction of more than 40 landfill remediation projects for Superfund projects and military installations since 1982. Geosynthetics have played a major role in the success of these projects. This paper focuses on COE involvement in various environmental restoration programs which use geosynthetics and the activities being conducted to further advance the state-of-the-practice in geosynthetic engineering. Geosynthetic guidance development and training by the COE are discussed along with examples of geosynthetic containment applications. In addition, geosynthetic design and construction issues related to geomembrane seam testing, interface friction testing, test sections, quality assurance/quality control (QA/QC) and monitoring are discussed.

Three-dimensional woven geotextiles for containment dike construction

Every year, approximately 300 million m 3 (400 million yd 3) of sediment is dredged from the United States' waterways (Fairweather, 1995). Although the primary purpose is to increase navigational capacities of channels, engineers are constantly seeking more effective and environmentally acceptable disposal methods for dredged materials. When the Port of Houston Authority faced this challenge, the Beneficial Uses Group (BUG) decided to utilize dredged material from the Houston Ship Channel to construct over 1720 hectares (4250 acres) of intertidal salt marshes. Starting in February 1994, three geosynthetic materials were installed along 1000 m (3300 ft) of dredged material containment levee at a demonstration marsh built on the east side of Atkinson Island. Proposed as possible cost-effective alternatives to conventional riprap, the three materials chosen included a cellular confinement system, fabricated geotextile tubes, and a three-dimensional woven geotextile for the shoreline protection. The three-dimensional woven geotextile was installed on 2H.-1 V slopes and secured using anchor trenches, hairpin-shaped reinforcing steel bar and duckbill anchors. To date, the product has helped to maintain a stable, nonerosive levee and promoted diversified aquatic vegetation (Anonymous, 1994). The project continues to be closely monitored by the Port of Houston Authority, the US Army Corps of Engineers, the Environmental Protection Agency, the National Resources Conservation Services and a host of other agencies. This paper describes the background, selection, installation, and performance of the three-dimensional woven geotextile used for erosion protection along 122 m (400 ft) of levee on this demonstration project. Chronological data, field observations and photographs are included to compliment the observations and conclusions made by the authors, and others, from the time of installation to present.

EXPERIMENTAL INVESTIGATION AND ANALYSIS OF HEC-6 RIVER MORPHOLOGICAL MODEL

Only comparatively few experimental studies have been carried out to investigate the performance of the HEC-6 river morphological model. The model was developed by the Hydrologic Engineering Center of the US Army Corps of Engineers. In this study, experiments were carried out in a 20 m long concrete flume 0.6 m wide with varying rectangular cross-sections. The channel bed is paved with uniform sand of D50 = 0.9 mm and D90 = 1.2 mm within the test reach of 12 m. Two types of experiments were carried out with sediment transport, one under steady uniform flow and another under steady non-uniform flow conditions. Nine steady uniform flow experiments were carried out to compare the measured equilibrium relationship of flow and sediment transport rate with two bedload formulae, namely, Du Boys and Meyer–Peter and Muller, and with three total load formulae, namely, Toffaleti, Laursen and Yang. It was found that even though the sediment transport consists of a certain portion of bedload, the total load formulae give satisfactory results and better agreement than the two bedload formulae. Five steady non-uniform flow experiments were carried out under various conditions of varying bed profile and channel width and also with sediment addition and withdrawal. The measured transient water surface and bed profiles are compared with the computed results from the HEC-6 model. It was found that the Toffaleti and Yang total load formulae used in the HEC-6 model give the most satisfactory prediction of actual bed profiles under various conditions of non-uniform flow and sediment transport. The effects of Manning's n, variations of sediment inflow, various sediment transport formulae, sediment grain size and the model numerical parameters, i.e. distance interval Δx and numerical weighting factor, on the computed water surface and bed profiles were determined. It was found that the selection of the sediment transport formulae has the most significant effect on the computed results. It can be concluded that the HEC-6 model can predict satisfactorily a long-term average pattern of local scour and deposition along a channel with either a small abrupt change in geometry or gradually varying cross-sections. However, the accuracy of the model prediction is reduced in the regions where highly non-uniform flow occurs.

Analysis of potential impacts to resident fish from Columbia River System Operation alternatives

The US Army Corps of Engineers, the US Bureau of Reclamation, and the Bonneville Power Administration initiated the Columbia River System Operation Review (SOR) in 1990. The SOR will assist agencies in comparing the benefits and risks to Columbia River uses and natural resources from alternative strategies for using Columbia River water. Focusing on 14 federal dams within the basin, the agencies are attempting to improve on the efficient and coordinated use of the Columbia River system. An initial screening of all potential strategies of reservoir operation was necessary to reduce the number of possibilities to a limited set for detailed analysis. To that end, the Resident Fish Work Group of the SOR developed spreadsheet models capable of assessing the impacts of different management strategies on resident fish at six storage reservoirs. The models include biological, physical, and hydrological relationships important to resident fish specific to each reservoir. Alternatives that kept the reservoirs near full pool and held stable during the growing season resulted in positive benefits to resident fish at all locations modeled. Conversely, alternatives designed to improve anadromous fish survival with increased instream flow generally had a negative impact on the resident fish in the reservoirs modeled. The models developed for resident fish in the screening analysis phase of the SOR were useful in assessing the relative impact to resident fish from a large number of alternatives. The screening analysis demonstrated that future analytical efforts must consider trade-offs among river uses/resource groups, among reservoirs throughout the basin, and among resident fish species within a reservoir.

City Utility Can't Escape Fees

By limiting its analysis of the cumulative effects of three dams to river temperature and turbidity and their influence on fish production, the US Army Corps of Engineers violated the National Environmental Policy Act.