An Economic Analysis of Sediment Control at Construction Sites: The Case of Greenville County, South Carolina (original) (raw)
Prediction of the Life Cycle Cost for Erosion and Sediment Control Measures
Commonly used Best Management Practices (BMPs) such as geotextile and mats, silt fence and sediment basins can be very effective in alleviating sediment stress to the streams. However, improperly placed, sized, or maintained BMPs can negatively impact stream biota and habitat, creating a more severe sedimentation/erosion problem. The effectiveness of the BMPs system depends on the regular operation and maintenance of the BMPs. However, the increased cost is known as barrier to the wider implementation of the BMPs by the developers and contractors. Therefore, the challenge is to develop a clear life cycle cost of BMPs which can be used in any development site. Life cycle cost (LCC) of a BMP is a combination of the installation, maintenance and removal costs of the various BMPs. In this research, software called Life Cycle Cost Decision Support System (LCC-DSS) has been developed to predict the LCC of the various BMPs desired to be installed within the construction site. Two scenarios have been adopted herein, the first one is the estimation of the LCC depend on the current prices available in the market. Whilst the second scenario is the prediction of the LCC based on the future prices in which the user is required to do some data input. The LCC-DSS has been verified and validated using real data from construction site in Malaysia and has shown convenient results which were confirmed by professional experts.
Erosion Prevention and Sediment Control Computer Modeling Project: Executive Summary
2001
Sedimentation Control Technical Study Committee ("Dirt 2") members generously shared their extensive knowledge and experience, actively participated through challenging discussions and provided an evolving philosophy of the paradigm shift that is needed to advance the multi-functionality of storm water, erosion prevention and sediment control system design and performance. As Dirt 2 chair, Dr. Benjamin C. Dysart provided continuous real-world advice and guidance, evaluated and critiqued alternative design considerations, and provided an eye towards adoption, implementation, and policy. Dr. Terry Sturm was the chair of the Modeling Element Advisory Committee. He was always available for synergistic conversations, kept the multiple project components on target and always encouraged the systems approach and rigorous scientific inquiry. His reviews of the executive summary and this final report were extensive and always enhanced understandability. The computer modeling advisory group members, Ben Dysart, Phil Freshley, Vince Howard, Earl Jenkins, Bill Jordan, and Karim Shahlaee, actively participated in guiding site selection, individual erosion and sediment control component, monitoring decisions and modeling philosophy. Two individuals substantially contributed to the critical start of this project by providing sites to monitor the performance of current-paradigm sediment control measures. Wayne Woodall arranged access and cooperation at both the residential and commercial sites. James Magnus provided us with one of his highway sites and opened doors for us to learn contractual arrangements that influence construction, maintenance and therefore performance, of sediment controls at highway construction sites. We would like to thank the site owners and project managers that provided not only site access but also support for in-field personnel during the monitoring timeframe. The next large hurdle was to find a cooperator for the full-scale model demonstration site. This was difficult to accomplish because involving us in a project entailed several potential liabilities. The storm water, erosion, and sediment control plan would be quite different from current practice, thus potentially exposing the cooperator to potential cost increases and delays in permitting. The design philosophy of placing sediment control installation on the critical path could increase the overall timeframe for site development and delay completion. A comprehensive monitoring program, with results being readily available to the public, and a highly visible project were other perceived impediments to locating a cooperator. Michael Breedlove expounded the virtues of this demonstration effort. Although there were potential liabilities, there were many and large advantages. Michael secured the willing cooperation of the Fulton County Board of Education and especially the support and commitment of Marcus Ray and Ollis Townes. The Big Creek School site became available for the model demonstration component of the project. Scott Southerland the project architect was very supportive of advancing site capabilities. Michael, and his team of design professionals, worked hand-in-hand with us in every phase of designing and implementing the storm water, erosion, and sediment control plan. He was critically instrumental in creating and accomplishing an incredibly successful project. Larry Hedges and Earl Jenkins encouraged accelerated permitting which was spear-headed by Raymond Wilke. Nothing really happens until a plan is successfully implemented on the ground. The Beers-Moody team of Chris Johnson and Karen Dunsmore, working with IMC's Bill Stinnett on initial earthwork and VECO's Norm Amend, who supervised the installation of most of the small-scale sediment controls, learned these new control measures and taught us the importance of flexibility in translating designs into reality. Fundamental to the project success were the daily inspections conducted by Beers-Moody personnel ensuring the proper functioning of control measures and the overall system. iii Eric Dawalt supervised and conducted soil sample analysis and was the lead contributor to Chapter 8, Cost Methodology of Alternative Erosion Prevention and Sediment Control Systems. Two graduate students in Civil Engineering at Georgia Tech were responsible for on-site data acquisition and maintenance of the eight monitoring systems installed at the Big Creek School site. Diana Weber and Mindy Hoepner ensured that the database was as complete as possible through their dedication.
SIGNIFICANT FINANCIAL AND ECONOMIC RISK FACTORS IN COASTAL LAND RECLAMATION PROJECTS
The demand for land required for construction and development has been rapidly increasing over the past 30 years in the global context because of population growth, especially in coastal cities. Therefore, coastal land reclamation (CLR) has drawn attention both internationally and regionally. However, CLR projects are complex and costly and, therefore, are often associated with numerous risks. Although risk management in CLR projects has been the focus of few past studies, they have not specifically focused on financial and economic risks. This study, therefore, aimed to identify the most significant financial and economic risk factors present in CLR projects to enable the management of those risks. The required empirical data were collected by conducting a two-round Delphi survey, comprising expert interviews and a questionnaire survey. The collected data were analysed using content and descriptive statistics. The results revealed 13 significant financial and economic risk factors of CLR projects. Quality of sand and soil was identified as the most important risk factor of CLR projects. Delayed payment, unpredictable safety and security conditions of the country, dredging volume and defaulting contractors and subcontractors were identified in the next top four ranking in this study.
Water Resources Research, 2004
1] On the basis of a spatially distributed sediment budget across a large basin, costs of achieving certain sediment reduction targets in rivers were estimated. A range of investment prioritization scenarios were tested to identify the most cost-effective strategy to control suspended sediment loads. The scenarios were based on successively introducing more information from the sediment budget. The relationship between spatial heterogeneity of contributing sediment sources on cost effectiveness of prioritization was investigated. Cost effectiveness was shown to increase with sequential introduction of sediment budget terms. The solution which most decreased cost was achieved by including spatial information linking sediment sources to the downstream target location. This solution produced cost curves similar to those derived using a genetic algorithm formulation. Appropriate investment prioritization can offer large cost savings because the magnitude of the costs can vary by several times depending on what type of erosion source or sediment delivery mechanism is targeted. Target settings which only consider the erosion source rates can potentially result in spending more money than random management intervention for achieving downstream targets. Coherent spatial patterns of contributing sediment emerge from the budget model and its many inputs. The heterogeneity in these patterns can be summarized in a succinct form. This summary was shown to be consistent with the cost difference between local and regional prioritization for three of four test catchments. To explain the effect for the fourth catchment, the detail of the individual sediment sources needed to be taken into account. INDEX TERMS: 1815 Hydrology: Erosion and sedimentation; 1803 Hydrology: Anthropogenic effects; 1806 Hydrology: Chemistry of fresh water; 1871 Hydrology: Surface water quality; KEYWORDS: investment, sediment, spatial modeling Citation: Lu, H., C. J. Moran, I. P. Prosser, and R. DeRose (2004), Investment prioritization based on broadscale spatial budgeting to meet downstream targets for suspended sediment loads, Water Resour. Res., 40, W09501,
A Law and Economics Approach to Resolving Reservoir Sediment Management Conflicts
Journal of the American Water Resources Association, 2005
The loss of the world's reservoir capacity to sedimentation can be mitigated by altering dam operations to release sediment downstream. However, legal uncertainty regarding whether dam owners are liable for damages to surrounding landowners due to altered operations provides a significant disincentive for sustainable sediment management. Past work recommends that courts apply a "rule of reasonableness" in assessing liability: dam owners should be held liable for damages only if they act unreasonably in altering operations, and surrounding landowners should take reasonable measures to mitigate foreseeable damage. Based on past cases, judicial determinations of reasonable reservoir management and reasonable precautionary measures by landowners are generally highly speculative, controversial, and based on limited information. Courts can ease the future burden of making these difficult determinations with rulings that create economic incentives for parties to act reasonably. For example, courts might entitle landowners to be free from sediment related damages, and protect the entitlement with a liability rule. This gives dam owners an economic incentive to release sediment only if the benefits of doing so outweigh court ordered damages to landowners. Past judicial decisions are largely consistent with this legal regime. (KEY TERMS: reservoir; sediment management; liability; dam management; dam decommissioning.)
Water
Sediment basins are temporary practices commonly used to detain stormwater runoff and capture suspended sediment on construction sites. A 79.0 m3 (2790 ft3) sediment basin testing apparatus at the Auburn University—Erosion and Sediment Control Testing Facility was used to provide a series of controlled and repeatable, large-scale tests to understand the performance of sediment basins and provide improvements. This research evaluated five sediment basin configurations over the course of 27 individual tests, including: (1) a standard configuration, (2) the addition of an excavated sump upstream of a ditch check, (3) the modification of the first baffle, (4) a high-rate lamella settler in upward flow, and (5) a high-rate lamella settler in parallel flow. The primary metric for evaluating performance and the treatment effectiveness of a configuration’s ability in capturing sediment was assessed from turbidity measured across the basin surface. Multiple linear regression analysis indicat...
Journal of Environmental Quality, 2010
Soil conservation benefi cial management practices (BMPs) are eff ective at controlling soil loss from farmlands and minimizing water pollution in agricultural watersheds. However, costs associated with implementing and maintaining these practices are high and often deter farmers from using them. Consequently, it is necessary to conduct cost-benefi t analysis of BMP implementation to assist decision-makers with planning to provide the greatest level of environmental protection with limited resources and funding. Th e Soil and Water Assessment Tool (SWAT) was used to evaluate the effi cacy of fl ow diversion terraces (FDT) in abating sediment yield at the outlet of Black Brook Watershed (BBW), northwestern New Brunswick. Diff erent FDT-implementation scenarios were expressed as the ratio of land area protected by FDT to the total cultivated area. From this analysis, we found that average annual sediment yield decreased exponentially with increased FDT protection. When the proportion of FDT-protected areas was low, sediment reductions caused by FDT increased sharply with increasing use of FDT. Similarly, marginal sediment yield abatement costs (dollar per tonne of sediment reduction) increased exponentially with increasing proportion of FDT-protected area. Th e results indicated that increasing land protection with FDT from 6 to 50% would result in a reduction of about 2.1 tonne ha-1 yr-1
New Economic Paradigm for Sustainable Reservoir Sediment Management
Journal of Water Resources Planning and Management
Water storage reservoirs can be either sustainable or exhaustible. In the absence of sediment management, reservoir storage is an exhaustible resource with long-term consequences. Previous economic planning of reservoirs essentially guaranteed non-sustainable solutions. This paper describes a new economic paradigm for economic assessments of new and existing reservoirs. The new economic paradigm provides a framework for comprehensive accounting of economic benefits and costs over a sufficiently long period of analysis, including cost estimates for dam decommissioning and lost benefits where sediments are not sustainably managed. A case study applies this framework to a hypothetical western US reservoir to quantitatively compare the status quo (i.e., no sediment management) with a selection of sediment management alternatives. Results indicate that sustainable sediment management can be less expensive than the consequences of ignoring sedimentation (e.g., eventual dam decommissioning and replacing lost storage capacity). Additional work shows that beginning sediment management within a decade of reservoir construction prevents the most severe impacts of sedimentation. An investigation of alternative discounting approaches indicates that the approach employed can have a significant impact on economic results.
Abstract. Local regulations in South Carolina must comply with SCDHEC standards, which require stormwater detention and sediment retention ponds be designed based on runoff from 2- and 10-year 24-hour rainfall events. Inadequate pond performance, particularly during more frequent, shorter duration and high intensity events, raises questions about the adequacy of the design standards. As one approach to answer these questions, a parametric study was conducted to evaluate pond performance during storms other than the regulatory 2- and 10-year 24-hour events, specifically for variable frequency, depth, and duration storms, and long- term. Results demonstrate stormwater and sediment ponds designed in accordance with current policies are not sufficient to control downstream flooding and channel aggradation-degradation. For better control, 24- hour extended detention of the 1-year 24-hour storm should be implemented. The study results also suggest stormwater detention and sediment retenti...