Cost‐Effective Sediment Dredge Disposal Options for Small Craft Harbors in Canada

Sediment dredge disposal options were reviewed to improve cost‐effectiveness and environmental safety for dredging of coastal sediments at the Department of Fisheries and Oceans Small Craft Harbours (DFO‐SCH) program in Canada. Historically, contaminated dredge sediments exceeding federal guidelines were disposed of in nearby landfills. Recent federal regulatory changes in sediment quality guidelines adopted by provincial regulators in Canada has resulted in updates to guidelines for disposal of contaminated solids in landfills. Updates now require specific and general disposal options for contaminated dredge material destined for land‐based disposal, resulting in more expensive disposal in containment cells (if contaminated sediments exceed federal guidelines). However, as part of this study, a leachate testing method was applied to contaminated sediments to simulate migration of potential contaminants in groundwater. Using this approach, leachate quality was compared to federal freshwater criteria and drinking water quality guidelines for compliance with new regulations. Leachate testing performed on the highest sediment contaminant concentrations triggered less than 2 percent potable water exceedances, meaning that most dredge spoils could be disposed of in privately owned or provincially operated landfill sites, providing less expensive disposal options compared to containment cell disposal. Current dredge disposal practices were reviewed at 35 harbor sites across Nova Scotia and their limitations identified in a gap analysis. Improved site management was developed following this review and consultation with interested marine stakeholders. New disposal options and chemical analyses were proposed, along with improvements to cost efficiencies for management of dredged marine sediments in Atlantic Canada. © 2013 Wiley Periodicals, Inc.     

Equipment choices for dredging contaminated sediments

This article describes the selection and field evaluation of dredging equipment and techniques for removal of highly contaminated sediments from the upper estuary of the Acusbnet River, a portion of the New Bedford Harbor Supetfund Project. Site conditions as related to dredge selection and operation, factors considered in selection of equipment, and various dredge types considered for use are described. Each of the dredge types is ranked according to the following criteria: availability, safety, potential for sediment resuspension, maneuverability, cleanup precision, cost and production, flexibility, required water depth for operation, ability to access the site, and compatibility with disposal options. A field pilot study comparing three dredge types indicated that dredging could be conducted at the site without a significant increase in the contaminant release from the upper estuary to the lower harbor.     

To Dredge or Not

The streams, rivers, freshwater lakes, and coastal and open ocean waters of the world have been used for centuries for the disposal of municipal and industrial wastes. During the twentieth century, the range and quantities of waste materials discharged to the world's fresh and salt waters have grown progressively, increasing the potential ecological and human health impacts. The types and quantities of organic and inorganic wastes reaching the surface waters and associated sediments have increased in proportion to a region's or nation's population and industrial growth. Many of the contaminaants deliberately or inadvertently discharged to waterways are hydrophobic, are not biodegradable, or are highly resistant to degradation resulting in the accumulation of organic and inorganic substances in the waters, bottom, and suspended sediments of impacted waterways. Because of their persistence, these compounds and trace metals bioaccumulate and bioconcentreate in the aquatic organisms that occupy the affected waterway. Because many of the discharged waste materials are relatively insoluble and readily sorb to particles, the bottom and suspended sediments will commonly have higher contaminant concentrations than the associated overlying waters. Concentrations will normally decrease downstream of the contaminant source areas due to inputs and dilution by sediments and waters from cleaner tributaries. Although the sediments will normally have the higher concentrations, considerable quantities of contaminants may be found in the aqueous phase requiring not only removal of the solids, but treatment of the associated water as well. This is particularly the case when the water to solids recovered during dredging may approach 10:1. Many of the persistent contaminants impacting a nation's waterways are readily sorbed to the finer‐grained, organic rich sediments. Reaches of rivers and streams, or areas amenable to deposition of organic rich clays and silts, result in the creation of “hot spots” of contamination, localized areas where higher contaminant concentrations are found. It is these “hot spots” that are at the center of a debate over whether to dredge or leave the contaminated sediments undisturbed to allow natural attenuation to work. It is well recognized that dredging is not able to remove all of the contaminated sediments; some portion of the resuspended sediments created during the dredgirg will be dispersed downstream. The issue is whether to physically removeportions of the mass of contaminants impacting waterwa‐ys or rely on natural attenuation. Environmental dredging is expensive and many argue not worth the effort because of the lack of effective technologies that will prevent redistribution of the material resuspended as apart oJthe dredging process and management of associated water. Opponents of dredging cite natural attenuation and burial by cleaner sediments as eflective mechanisms to reduce the concentration of contaminants. Dredgingproponents argue the contaminant sources and accumulated hot spots must be removed in order to accelerate ecological recovery of the impacted waterway as well as reduce impacts to the environment and to public heulth. During thc next several years, decisions will be made by the U.S. Environmental Protection Agemy (USEPA) on whether to dredge major and minor waterways involving millions of cubic yards of contaminatedsedinaents requiring expenditures of hundreds of millions oj‐dollars by the responsible parties. © 2000 John Wiley & Sons, Innc.     

Concepts for sediment restoration on the palos verdes shelf,California

This article summarizes a study conducted by the U.S. Army Engineer Waterways Experiment Station to develop technical information and to evaluate the engineering feasibility of restoration alternatives for DDT-and PCB-contaminated sediments on the Palos Verdes shelf and slope near Los Angeles, California. The study evaluated the nonremoval alternative of in-place capping of contaminated sediments on the shelf and slope; removal of contaminated sediments using conventional and specialized dredging equipment and deep ocean mining equipment; treatment of contaminated sediments; and disposal of contaminated sediments in confined (diked) disposal facilities (CDFs), contained aquatic disposal (CAD) sites, upland landfills, and deep ocean basin sites. Cost estimates of the various alternatives were also prepared. This article concludes that restoration of the contaminated sediments is technically feasible. Sediments on the shelf and slope can be removed using available dredging technologies for deep water environments. In-place capping, CAD, and CDF alternatives are technically feasible. The deep ocean basin disposal alternative is not feasible from the technical or regulatory standpoint. The treatment alternative is not feasible from the implementability and economic standpoint.     

Safe management of hazardous waste

The size and the health significance of the hazardous waste problem are reviewed. Proper engineering and management practice are discussed, including the elimination, if possible, reduction, changing processes and product lines, treatment and reuuse, and disposal by landfill and incineration. Exports should be drasti cally reduced, also using complex administrative measures. International organizations concerned should encourage good national and international management practices. A siting for collection, treatment and disposal, remote from human habitation, and established under an international agreement, would release countries from managing a difficult problem within their own national borders.     

Factors and values of willingness to pay for improved construction waste management--a perspective of Malaysian contractors

Malaysia is facing an increase in the generation of waste and of accompanying problems with the disposal of this waste. In the last two decades, extensive building and infrastructure development projects have led to an increase in the generation of construction waste material. The construction industry has a substantial impact on the environment, and its environmental effects are in direct relation to the quality and quantity of the waste it generates. This paper discusses general characteristics of the construction contractors, the contractors' willingness to pay (WTP) for improved construction waste management, determining factors which affect the amount of their willingness to pay, and suggestions and policy implications in the perspective of construction waste management in Malaysia. The data in this study is based on contractors registered with the construction industry development board (CIDB) of Malaysia. Employing the open ended contingent valuation method, the study assessed the contractors' average maximum WTP for improved construction waste management to be RM69.88 (1US$=3.6 RM) per tonne of waste. The result shows that the average maximum WTP is higher for large contractors than for medium and small contractors. The highest average maximum WTP value is RM88.00 for Group A (large contractors) RM78.25 for Group B (medium-size contractors) and RM55.80 for Group C (small contractors). One of the contributions of this study is to highlight the difference of CIDB registration grade in the WTP for improved construction waste management. It is found that contractors' WTP for improved waste collection and disposal services increases with the increase in contractors' current paid up capital. The identified factors and determinants of the WTP will assist the formulation of appropriate policies in addressing the construction waste problem in Malaysia and indirectly improve the quality of construction in the country.     

Impact of Construction Waste Disposal Charging Scheme on work practices at construction sites in Hong Kong

Waste management in the building industry in Hong Kong has become an important environmental issue. Particularly, an increasing amount of construction and demolition (C&D) waste is being disposed at landfill sites. In order to reduce waste generation and encourage reuse and recycling, the Hong Kong Government has implemented the Construction Waste Disposal Charging Scheme (CWDCS) to levy charges on C&D waste disposal to landfills. In order to provide information on the changes in reducing waste generation practice among construction participants in various work trades, a study was conducted after 3 years of implementation of the CWDCS via a structured questionnaire survey in the building industry in Hong Kong. The study result has revealed changes with work flows of the major trades as well as differentiating the levels of waste reduced. Three building projects in the public and private sectors were selected as case studies to demonstrate the changes in work flows and the reduction of waste achieved. The research findings reveal that a significant reduction of construction waste was achieved at the first 3 years (2006–2008) of CWDCS implementation. However, the reduction cannot be sustained. The major trades have been influenced to a certain extent by the implementation of the CWDCS. Slight improvement in waste management practices was observed, but reduction of construction waste in the wet-finishing and dry-finishing trades has undergone little improvement. Implementation of the CWDCS has not yet motivated subcontractors to change their methods of construction so as to reduce C&D waste.     

Sand Cap Placement and Cap Thickness Monitoring: A Case Study at a Confined Disposal Facility

Thin sediment capping is a commonly used technique to prevent mobilization of contaminants from sediments into the environment. A 70‐m‐deep subaqueous confined disposal facility (CDF, 350,000 m²) at Malmøykalven, Oslofjord, which received dredged contaminated sediments from Oslo Harbor, was capped with 148,900 m³ of sand in 2009. This research serves as a case study regarding some of the key considerations involved with the cap placement and monitoring of the cap layer. Uncertainty is included in all the cap thickness monitoring methods and a combined use of them provided a better understanding of the cap coverage and structure at the site. An open water disposal model (STFATE) was used to simulate the behavior of the barge‐released cap material. The modeling results were consistent with field observations regarding the material spread, and the results provided insight into the relatively high material losses calculated. Better knowledge obtained of material settling resulted in cap properties and cap monitoring methods that are useful when planning similar operations. ©2015 Wiley Periodicals, Inc.     

Cost estimating of the closure/post-closure phase

The U.S. Department of Energy (DOE) is beginning major environmental restoration projects of both active and inactive sites throughout the United States. The problems at the sites include contaminated soils, groundwater and surface waters, structures, and old waste disposal areas. IT Corporation, under the direction of the Office of Independent Cost Estimating (OICE) for DOE, developed a list of environmental problems at the sites and probable cleanup technologies and techniques that could be used. Estimated unit costs were then developed for these cleanup technologies, using available data and references. Some procedures developed were common to many or all cleanup projects. These included site characterization, remedial investigation (RI), feasibility studies (FS), and the closure/post-closure phase. The article will focus on cost estimating of the closure/post-closure phase of a cleanup project. The cost data provided are for budget level or check estimates. Site-specific conditions as well as items peculiar to the environmental industry, such as governmental regulations and community relations, can influence both the cost and duration of a cleanup project.     

Underwater treatment of lead-contaminated sediment

The sediment associated with the reconstruction of a bridge pier was classifiable as hazardous by the Toxicity Characteristic Leaching Procedure (TCLP), due to elevated concentrations of lead. However, RCRA regulations do not classify the sediment as hazardous unless it is moved. RMT designed an in-situ, underwater treatment process to render the sediment nonhazardous, using phosphate-based chemistry before dredging. Subsequent sediment management was conducted without the additional regulatory requirements and costs associated with managing hazardous waste.     

Integrating Groundwater Conservation and Reuse into Remediation Projects

Groundwater remediation projects generally involve extraction and treatment of contaminated groundwater. The current state of the practice does not include an emphasis on conservation and reuse of groundwater. Consequently treated groundwater is typically disposed in sanitary or storm sewers. Longstanding water conservation and reuse practices in the municipal wastewater industry provide a body of experience available to the remediation industry. Case studies of conservation and reuse options for groundwater at remediation sites have been found across a broad range of geographic settings and regulatory jurisdictions. The intent of this article is to stimulate a more holistic view of the groundwater associated with remediation projects and to promote conservation and beneficial reuse of a vital natural resource. © 2014 US Sustainable Remediation Forum     

Targeted intervention strategies to optimise diversion of BMW in the Dublin, Ireland region

Urgent transformation is required in Ireland to divert biodegradable municipal waste (BMW) from landfill and prevent increases in overall waste generation. When BMW is optimally managed, it becomes a resource with value instead of an unwanted by-product requiring disposal. An analysis of survey responses from commercial and residential sectors for the Dublin region in previous research by the authors proved that attitudes towards and behaviour regarding municipal solid waste is spatially variable. This finding indicates that targeted intervention strategies designed for specific geographic areas should lead to improved diversion rates of BMW from landfill, a requirement of the Landfill Directive 1999/31/EC. In the research described in this paper, survey responses and GIS model predictions from previous research were the basis for goal setting, after which logic modelling and behavioural research were employed to develop site-specific waste management intervention strategies. The main strategies devised include (a) roll out of the Brown Bin (Organics) Collection and Community Workshops in Dún Laoghaire Rathdown, (b) initiation of a Community Composting Project in Dublin City (c) implementation of a Waste Promotion and Motivation Scheme in South Dublin (d) development and distribution of a Waste Booklet to promote waste reduction activities in Fingal (e) region wide distribution of a Waste Booklet to the commercial sector and (f) Greening Irish Pubs Initiative. Each of these strategies was devised after interviews with both the residential and commercial sectors to help make optimal waste management the norm for both sectors. Strategy (b), (e) and (f) are detailed in this paper. By integrating a human element into accepted waste management approaches, these strategies will make optimal waste behaviour easier to achieve. Ultimately this will help divert waste from landfill and improve waste management practice as a whole for the region. This method of devising targeted intervention strategies can be adapted for many other regions.     

Interactions of Natural Colloidal Material and Phenanthrene in the Aquatic Environment

Resuspension of contaminated aquatic sediments by natural and anthropogenic activities (i.e., dredging, boat activities, fish, wildlife, storms, runoff) increases the flux of natural colloidal material and colloidally bound contaminants into the overlying water column. Colloidal material extracted from lower Fox River sediments was analyzed for various physical and chemical characteristics and subjected to batch aggregation studies under controlled conditions of pH (～3–8) and colloid concentrations (5 and 9 mg L^?1 as TOC equivalents) in the presence of dissolved phenanthrene in solution. Under water chemistry conditions where pH and K⁺ concentration are typical of most natural waters (10^?2 M K⁺ and pH～8), the presence of phenanthrene in solution (average [phen] = 0.2–0.4 mg/L) prevents particle aggregation and decreases the settling rate of these particles. Ultimately, this increases the total concentration of colloidally bound contaminants in the water column. Dredging is the most popular remediation technique for removing contaminated sediments from the aquatic environment. However, this laboratory study suggests that for typical waters, dredging may potentially elevate the concentrations of contaminants found in the water column. © 2001 John Wiley & Sons, Inc.     

Medical waste management in Trachea region of Turkey: suggested remedial action.

The main objective of this paper was to analyse the present status of medical waste management in the Trachea region of Turkey and subsequently to draw up a policy regarded with generation, collection, on-site handling, storage, processing, recycling, transportation and safe disposal of medical wastes. This paper also presents the results of study about awareness on how to handle expired drugs. Initially all health-care establishments in Tekirda?, Edirne and Kyrklareli provinces in Trachea region were identified and the amounts of hospital wastes generated by each of them were determined. Current medical waste-management practices, including storage, collection, transportation and disposal, in surveyed establishments were identified. Finally, according to results, remedial measurements for medical waste management in these establishments were suggested. Unfortunately, medical wastes are not given proper attention and these wastes are disposed of together with municipal and industrial solid wastes. The current disposal method is both a public health and environmental hazard. When landfill sites are visited, many scavengers can be seen sorting for recyclable materials, a practice which is dangerous for the scavengers. In addition, it was found that some staff in health-care establishments are unaware of the hazard of medical wastes. It is concluded that a new management system, which consists of segregation, material substitution, minimization, sanitary landfilling and alternative medical waste treatment methods should be carried out. For the best appropriate medical waste management system, health-care establishment employers, managers and especially the members of house- keeping divisions should be involved in medical waste management practice.     

Expect the best but plan for the worst: Negotiating contracts for remediation services

The risks associated with environmental remediation projects are of concern to engineers, consultants, contractors, owners, and the public. The cost, scheduling, and other uncertainties inherent in performance of construction at sites contaminated by hazardous substances dictate caution with respect to contract terms. Further, the possibility that conditions will be exacerbated by the work, or the public or workers exposed to on-site substances, makes remediation projects of particular concern to those who will be held accountable for the effects and impacts of such substances. This article discusses particularly important contractual issues and suggests approaches for liability allocation and incentives. Practical, effective, realistic approaches to management of environmental remediation are presented, including the form of contract utilized, negotiated terms, attention to contractor selection and management, and the parties' relative economic strength.     

Genotoxicity of leachates from highly polluted lowland river sediments destined for disposal in landfill

The Matanza-Riachuelo is one of the most polluted rivers of Latin America. The complex chemical mixture of pollutants discharged into the river is accumulated in the river sediments. In this paper, Matanza-Riachuelo river sediment composition and genotoxicity were tested in order to develop a cost-effective, environmentally sound option for disposal and management of contaminated dredged materials. Sampling was performed in a rural area, in a solid waste dumpsite and also in an urban and industrial area. The concentrations of total heavy metals increased from the upper basin to the lower basin. The Ames Salmonella typhimurium test and the Saccharomyces cerevisiae D7 test were performed using toxicity characteristic leachate procedure (TCLP) leachates. The concentrations of copper, lead, and chromium in the leachates exceeded the guide levels for the protection of aquatic life. Low concentrations of organic chlorinated compounds were detected in the leachates. Genotoxic profiles were obtained by testing TCLP leachates from polluted sediment samples with Salmonella typhimurium, Saccharomyces cerevisiae D7, and water sediment suspension with Allium cepa test. No mutagenicity effects on Ames test were observed. Gene conversion and mitotic reversion in Saccharomyces cerevisiae D7 and chromosome aberration in Allium cepa were induced by the sediment samples. Results obtained suggest that dredged sediments could be classified as genotoxic hazardous waste.     

The Use of Subbottom Profiling in Refining Dredge Cuts for a Large‐Scale Sediment Remediation Project

A number of different techniques were employed to locate the target dredge grade on a large‐scale Canadian sediment remediation project. These techniques included various coring events, Seabed Terminal Impact Newton Gradiometer (STING) testing, and geotechnical borings. Despite these techniques, the data set for interpolation of the dredge grade was widely spaced, and some of the investigations were not specifically intended to be used for defining the dredge grade. In order to reduce the risk of extra expenses from contractor claims resulting from differing sediment conditions, more precise planning was required. Due to the size of the area and the desired accuracy, subbottom profiling was identified as a potential tool to provide high‐density coverage across the site. As with any geophysical tool, ground truth data were required to verify and aid in interpretation. This article describes how subbottom profiling was used to refine the dredge grade for the target layer, the associated challenges related to signal loss in some areas, and how they were overcome. ©2017 Wiley Periodicals, Inc.     

Bioremediation of contaminated soil and sediment by composting

There are many well‐established bioremediation technologies applied commercially at contaminated sites. One such technology is the use of compost material. Composting matrices and composts are rich sources of microorganisms, which can degrade contaminants to innocuous compounds such as carbon dioxide and water. In this article, composting of contaminated soil and sediment was performed on a laboratory bench‐scale pile. Fertilizer was added to increase the nutrient content, and the addition of commercial compost provided a rich source of microorganisms. After maintaining proper composting conditions, the feasibility of composting was assessed by monitoring pH, total volatile solids, total microbial count, temperature, and organic contaminant concentration. The entire composting process occurred over a period of five weeks and resulted in the degradation of contaminants and production of compost with a high nutritional content that could be further used as inocula for the treatment of hazardous waste sites. © 2006 Wiley Periodicals, Inc.