http://www.mactec.com/news/press-room/default.aspx Channel For MACTEC Press Releases 4/12/1977 10 http://www.mactec.com/News/publications/technical-papers/docs/Joint_Reg_Radionuclides_at_CYAPCO_Haddam.pdf Premature deterioration of concrete bridges in the United States has been identified as a major problem with respect to cost of repair and rehabilitation. Most often, chloride ion penetration and subsequent corrosion of the reinforcement is the cause. Many studies have been conducted to develop concrete mixtures that will better protect the reinforcement from corroding. However, due to variability in concrete materials from one location to another, a universal solution cannot be developed. Unique approaches, each intended for a particular geographical area, are therefore needed to ensure full compatibility between locally available materials. As a part of Indiana's high-performance concrete (HPC) bridge project, specimens from three HPC concrete mixtures and one conventional mixture were prepared and tested. The focus of the testing was to compare the ability of the four different mixtures to resist chloride ion penetration and reinforcement corrosion. Three sets of corrosion specimens were prepared from each mixture and the effective chloride ion diffusion coefficient was determined by two different test methods. These methods were chloride ponding and electrical indication of concrete's ability to resist chloride ion penetration. Correlation between results from the two test methods used to access concrete's ability to resist chloride ion ingress was good. The results presented in this paper include one-year corrosion data. http://www.mactec.com/News/publications/technical-papers/effectiveness-of-High-Performance-Concrete-in-resisting-chloride-ion-penetration.aspx Abstract Nitrate contaminated groundwater is a growing problem in the U.S and has received increased attention from regulators. Several approaches have been applied to remediate groundwater, but most have high engineering and operational costs associated with them. This paper presents an in situ biodenitrification technique applied to remediate groundwater nitrate contamination in the 32 acre Pond Area of a closed mineral processing Facility. Methanol is being injected directly into the aquifer as a food source for native bacteria to enhance natural biodenitrification. Methanol was chosen for this remediation project due to its low cost and ease of handling. This technique has reduced the nitrate concentrations an average of 57 percent at the Facility since treatment began in September 2001. Based on the success of this technique, there are plans to expand the system to speed the complete remediation of the Facility. http://www.mactec.com/News/publications/technical-papers/in-situ-Biodenitrification-case-study.aspx As a part of a larger study, the effects of different humidity and temperature conditions during curing of high-performance concrete on compressive strength and selective durability properties were compared. Cylinders from three highperformance concrete mixtures and a control mixture were prepared. The cylinders from each mixture were divided into four groups. The following curing conditions were evaluated: standard moist curing, moist curing for three days followed by curing at 50 % relative humidity, temperature-match-curing for the first day followed by moist curing, and curing in sealed plastic molds. Results from compressive strength and electrical indication of concrete's ability to resist chloride ion penetration tests indicate that curing concrete at 50 % relative humidity compromises compressive strength development and resistance to chloride ion penetration. Curing the specimens in sealed forms from the time they were cast until they were tested yielded results that were comparable to those obtained from continuously moist cured specimens. Accelerated curing of specimens for electrical indication of concrete's ability to resist chloride ion penetration appeared to be a valid method for obtaining 28-day results that are comparable to those obtained after 91 days. http://www.mactec.com/News/publications/technical-papers/comparison-of-different-curing-methods-for-High-Performance-Concrete.aspx Olin Corporation operates a large groundwater pump and treatment system as part of the remedial action program at its McIntosh, Alabama plant. As a result of historical releases at this plant, some of the groundwater became contaminated with salt brine, mercury, various organic compounds, and acid. Because of the groundwater's low pH, aluminum and iron have been extracted from native soil and are dissolved in the groundwater. To allow removal of the mercury from the groundwater without generating aluminum and ferric hydroxide sludge, an innovative slurry treatment system was developed. The first step in the process is to acidify the slurry to re-dissolve the aluminum and iron. The acidified solution can then be treated in activated carbon without the aluminum or iron precipitating and fouling the system. Mercury is concentrated in the activated carbon and can be ultimately reclaimed by retorting the spent carbon. The mercury-free solution is neutralized and discharged. Aluminum and iron are re-precipitated in this step but is discharged within the existing NPDES permit limits. The treatment system has been in operation since May 2001. The avoidance of sludge dewatering and disposal costs has offset the additional cost of the slurry processing facilities. This approach shows promise in eliminating aluminum and iron fouling in other groundwater treatment systems. http://www.mactec.com/News/publications/technical-papers/innovative-hydroxide-slurry-processing-system-reclaims-mercury-from-groundwater.aspx Tetrachloroethene (PCE) in groundwater at a manufacturing facility in New England is attenuating through a combination of biodegradation and tidal processes before it discharges to a tidal creek. Modeling studies assessed the relative contributions of these two major processes in reducing PCE concentrations within the plume, from near solubility concentrations at the source area to concentrations below risk-based criteria for discharge of groundwater to surface water. Simulations using the BIOCHLOR model showed that biodegradation could reasonably account for only part of the observed PCE concentration reduction. A one-dimensional transient numerical model of groundwater flow and transport simulated the long-term effects of tidal water level fluctuations on PCE concentrations to assess whether these fluctuations could account for the remainder of the concentration reduction. Groundwater levels in wells near the tidal creek fluctuate by up to several feet in response to tidal changes. The dynamically changing flow velocities within the tidally-affected zone can reduce PCE concentrations in groundwater migrating toward the creek by accentuating hydrodynamic dispersion and mixing of groundwater with water from the creek. Model simulations indicate that these processes could reduce concentrations within the aquifer by more than 90 percent within a zone of only 60 feet from the creek. This reduction, combined with that produced by biodegradation processes, appears capable of producing a stable plume front of relatively low PCE concentrations, as has been observed near the creek since monitoring began in 1997. Based on these results, a monitored natural attenuation remedy has been accepted for the PCE plume. http://www.mactec.com/News/publications/technical-papers/natural-Attenuation-of-Tetrachlorethene-by-Biological-and-Tidal-Processes.aspx Computer modeling technology has advanced to the point that implementation of modeling programs for small-scale potable water distribution systems such as those at Air Force installations is now easily and effectively accomplished. This paper summarizes Pacific Environmental Services' (PES) efforts to implement a water distribution modeling software package at two U.S. Air Force Bases. Model development was required to perform comprehensive hydraulic analyses of each potable water distribution system. The model was also used to evaluate specific operational scenarios, as well as evaluate and optimize several construction projects under consideration. These efforts were part of a bigger project to conduct a water vulnerability assessment that included evaluations of the redundancy of facilities, the need for back-up treatment systems, the ability of facilities to deliver adequate pressure for both normal use and fire suppression, and manpower requirements. http://www.mactec.com/News/publications/technical-papers/implementation-of-a-Water-distribution-system-computer-model.aspx Current regulations for unrestricted release are based on annual dose equivalent. Unless one desires to use very conservative "screening levels," dose modeling must be accomplished to derive an areal or volumetric limit or concentration value for release purposes. Such derived limits are referred to as "Derived Concentration Guideline Levels" (DCGL). This paper describes the process employed to derive DCGLs for building surfaces contaminated with uranium and its decay progeny based on annual dose equivalent and the innovative means employed during the derivation. Health Phys. 84(Supplement 1):000-000; 2003 http://www.mactec.com/News/publications/articles/development-of-Dose-Based-release-limits-for-unrestricted-release-of-a-radio-chemistry-laboratory.aspx Little Stringybark Creek restoration project is the first of its kind, focusing on reducing stormwater runoff using LID strategies across an entire sub-watershed. Urban streams around the globe demonstrate common characteristics associated with the increased imperviousness of their watersheds, including a flashy hydrograph, elevated concentrations of pollutants, altered channel morphology, and increased dominance of pollution tolerant species. Urban streams cannot be restored to pre-disturbance stream health conditions without addressing the combined water quality and hydrologic disturbance (increased volume and frequency of polluted stormwater runoff) from impervious areas delivered by drainage infrastructure in developed watersheds. This poses a great challenge for stream restoration, since it is much easier to implement local or reach scale in-stream or riparian projects than to reduce the stormwater impacts of impervious areas in a catchment. One of the key needs for the protection or restoration of streams in urban or urbanizing catchments is, therefore, a better understanding of specific and practical stormwater management objectives at the catchment and site scale aimed at addressing hydrologic characteristics that affect streams. http://cedb.asce.org/cgi/WWWdisplay.cgi?0812082 Alteration in state and federal envionmental regulations and statutes in the last ten years has had unexpected impacts on the acquisition, sale, and financing of buinesses and commercial real property. Corporate management and real estate owners are expending significant temporal and financial resources to assess environmental consequences of transactions which had been previously ignored. Businesses are finding that poorly timed or inadequate assessments of environmental liability can have unforseen and costly effects. Indifference to contaminated ground and surface water, soil and buildings can lead to exposure far exceeding the purchase price of the property or the assets or stok of a business. The casual, unthining and negilgent disposal of hazardous wastes and substances was an ingrained behavior so common in this country that many corporate managers, even to this day, are genuinely surprised at the impact of new environmental laws. Businessmen and their advisors are having to recognize and negotiate transactions of particular environmental vulnerability, and the legal and factual issues pertaining to them. They are having to devise ways in which per-purchase assessments by legal and engineering consultants should be organized so that environmental contamination and risks can be evaluated prior to closing. The form and substance of transactions are being altered to address environmental issues which impact on corporate and property values. What transactionsmay be susceptible to environmental liability? In what ways has the law been so altered to depart from traditional approaches? How should businessmen efficiently and effectively assess the environmental condition of a business or a parcel of real property? This article examines briefly the motivation of the environmental component of the pre-acquisition due diligence process, why it has become a necessity, and how prudent buyers and sellers should implement the process. http://www.mactec.com/News/publications/technical-papers/environmental-assessments-as-components-of-Pre-Acquisition-due-diligence.aspx A pollution prevention opportunity assessment (PPOA) was conducted at U.S. Naval Station Mayport in the following areas: (1) evaluating recycle and reuse options for petroleum oils and lubricants (POLs) at the Public Work Center - Transportation (Building 25); and (2) identifying options to reduce the amount of waste rags being generated throughout the Naval Station. For the evaluation of recycle and reuse options for POLs, information was obtained primarily from vendors of the equipment. The POLs studied included hydraulic fluids, engine oils, hydraulic and transmission fluids, and ethylene glycol (antifreeze). The evaluation examined technical and economic feasibility of implementing the options. Recommendations for testing and field evaluation of each alternative were made. For the waste rag reduction study, the major sources of rag usage at the Naval Station were identified and the reasons for the rag waste generation were identified. Recommendations were made for reducing the generation of wastes that require wiping, using alternative cleaning methods, product substitution, and implementation of recycling. http://www.mactec.com/News/publications/technical-papers/pollution-prevention-alternatives-for-Public-Works-Center-and-Waste-Fluids-Naval-Station-Mayport.aspx Fly ash and silica fume are two pozzolans that have been widely used for improved concrete strength and durability. Silica fume displays a greater pozzolanic reactivity than fly ash primarily due to its finer particle size. The reactivity of fly ash can be improved by reducing its particle size distribution. This paper discusses the fresh and hardened properties of concrete made with an ultra-fine fly ash (UFFA) produced by air classification. Durability testing for chloride diffusivity, rapid chloride permeability, alkali-silica reaction (ASR), and sulfate attack was also conducted. It was found that at a given workability and water content, concrete containing UFFA could be produced with only 50% of the high-range water-reducer dosage required for comparable silica fume concrete. Similar early strengths and durability measures as silica fume concrete were observed when a slightly higher dosage of UFFA was used with a small reduction (10%) in water content. http://www.mactec.com/News/publications/technical-papers/properties-of-Concrete-Containing-Ultra-Fine-Fly-Ash.aspx Strict compliance with environmental regulartions has not been designated as the highest priority with many in the hierarchy of Corporate America. Many large national and international ocmpanies are decentralized to the extent that regulatory compliance is the responsibility of plan management or the plant engineering staff. For smaller companies, environmental issues are often delegated to plant engineering, safety, or human resources departments where they become part of many problems to be solved. For most companies and individuals, it was anticipated that good faith efforts for compliance and cooperation with Agency Inspectors would serve to mitigate non-compliance problems. Although large fines have received great attention int he press, many environmental mangers have flet these "deterrent fines" would be issued only for flagrant violations. Many managers have believed that a goal of general compliance was acceptable and that cooperation with the regulators would avoid penalties. Although this strategy was functional in the early 1980s, this approach to regulatory compliance will not be acceptable to enforcement officials and the courts. For many companies, as well as institutions and governement agencies, failure to so comply with environmental regulations has resulted in large fines and a requirement to perform a mult-media assessment of regulatory compliance. Federal, state and local environmental regulatory authorities as well as the Department of Justice and the court system have launched a not-so-subtle program to increase compliance. http://www.mactec.com/News/publications/technical-papers/key-to-Environmental-Responsibility.aspx Fine aggregate characteristics have an important influence on water demand and related properties of concrete. Several test methods for measurement of fine aggregate angularity are reported in the literature. These tests typically provide a single number that represents the bulk, or average angularity of the sand. An understanding of the relationship between bulk measures of angularity, individual particle geometry and shape characteristics, and concrete properties is important to aggregate producers, concrete suppliers, consulting engineers, other design professionals, particularly as existing deposits of sand are consumed and alternate sources must be developed. As part of a comprehensive research program on manufactured sand properties and their effects on fresh and hardened concrete properties, an image analysis technique was developed to determine the shape characteristics by photographing and analyzing sets of individual grains of sand. The outlines of the grains were analyzed using a variety of geometrically derived characteristics. The relationship between particle shape characteristics and a common measure of bulk angularity, void content (ASTM C 1252), was then examined. Results of the study indicated that void content was significantly influenced by the presence of deep indentations in the surface of the sand particle and deviations from a cubical particle shape. http://www.mactec.com/News/publications/technical-papers/relationship-between-Particle-Shape-content-of-fine-aggregate.aspx AFI 32-1066 requires each Air Force installation to conduct a comprehensive backflow survey every five years to evaluate all facilities and water-using equipment and systems. Trained backflow personnel must identify all existing and potential cross-connections to the potable water system, assess the adequacy of existing backflow protection, and determine the potential need for additional backflow protection. This typically requires the collection of an appreciable quantity of data on hardcopy forms, which must later be entered into a database. To streamline this process, MACTEC Federal Programs, Inc. (MACTEC) designed a Backflow Prevention Device (BPD) database tailored for the direct entry of data collected during the survey. The database, used at fifteen USAF Bases around the country, was developed using Microsoft Access® 2000 for the desktop management component and Syware Visual CE® for the PocketPC field collection component. Field data collected using the PocketPC synchronizes directly with the desktop database, eliminating the need to re-enter information from the paper forms. These tools assist base personnel in the continued upkeep and maintenance of their BPD program by allowing for quick and efficient field data collection as well as providing a tool for device management and printing standard Air Force forms, such as AF Form 848. The database was designed to be compatible with the Tri-Services Spatial Data Standards (TSSDS), which allows for integration with the Base GIS systems. The database allows management of cross-connection information regarding: Facilities: name, address, point of contact (POC), and POC phone number. Cross-connections and BPDs: location, floor, room number, manufacturer, model, size, device type, date surveyed, hazard, service connection, back siphonage potential, back pressure potential, pollutant, status, location sketch, digital photograph, additional comments, and testing data. Water Customers and Surveyors: name, address, business type, POC, and POC phone number. This paper reviews cross connection and backflow prevention device requirements, past survey methodologies, and presents MACTEC'S Water Tool alternative. http://www.mactec.com/News/publications/technical-papers/stream-lining-Cross-Connection-Surveys-using-Pocket-PCs.aspx http://www.mactec.com/News/publications/technical-papers/docs/Great_Basin_Anthropological_Conference_Poster.pdf In situ remediation of contaminated groundwater has received significant attention throughout the environmental industry. One of the challenges with in situ techniques is the delivery of the amendments to the areas that need remediation. In situ remediation techniques require a detailed understanding of the subsurface geology and hydrogeology to be effective. Several approaches have been applied to remediate groundwater contaminants in situ; however, most techniques reported in the literature have been small pilot scale tests. Presented here is our experience applying an in situ remediation technique over 48 acres of a 70 acre closed mineral processing facility. The initial groundwater nitrate as nitrogen (nitrate N) concentrations ranged from 10 milligrams per liter (mg/L) to 2,200 mg/L. Based on the approach described here the nitrate concentrations have decreased an average of 41 percent across the site and have allowed for post remediation compliance monitoring beginning 3 years after treatment began. http://www.mactec.com/News/publications/technical-papers/in-Situ-Remediation-to-Remove-Nitrate-from-Groundwater.aspx