Petersen C.M.,Camp Dresser and McKee Inc. |
Rifai H.S.,University of Houston |
Villarreal G.C.,RBF Consulting |
Stein R.,Texas Commission on Environmental Quality
Journal of Environmental Engineering | Year: 2011
Bacterial levels in Buffalo Bayou in Houston commonly exceed contact recreation standards. Potential sources of bacteria include wastewater treatment plants, sanitary sewer overflows, septic systems, wet and dry nonpoint-source discharges via direct runoff and pipes, direct deposition, and sediment. A water-quality model in the Hydrologic Simulation Program-FORTRAN (HSPF) was calibrated and validated for hydrology, sediment, and Escherichia coli and subsequently used to evaluate the impacts of the bacterial sources in the watershed. In addition, simple estimates of bacterial loads were calculated along with source evaluations from load duration curves. Load reductions based upon the simple estimates indicated that water-quality standards were met by reducing dry-weather indicator bacterial loads by 69% and wet-weather loads by 98%. When these load reductions were implemented in the HSPF model, however, standards were not met under dry-weather conditions. Residual nonpoint-source loading was found to cause the discrepancy between simple load estimate calculations and the developed water-quality model. This paper demonstrates that runoff can play a significant role in maintaining high levels of bacteria under all flow conditions and that understanding the temporal variations in bacterial source loading is critical to ensure that load reductions will achieve water-quality standards. © 2011 American Society of Civil Engineers.
Mayer B.K.,Marquette University |
Mayer B.K.,Arizona State University |
Gerrity D.,Arizona State University |
Gerrity D.,University of Nevada, Las Vegas |
And 3 more authors.
Critical Reviews in Environmental Science and Technology | Year: 2013
Eutrophication caused by excess phosphorus (P) loading poses a serious environmental risk to freshwater bodies around the world. While conventional P-removal technologies often satisfy maximum effluent levels of 1,000 μg-P/l, the resulting environmental P concentrations can still contribute to eutrophication. The challenge remains to achieve low total P levels of ≤ 10 μg-P/l in very large water flows. This issue is often exacerbated by the presence of unreactive organic phosphorus. The authors critically assess innovative developments in advanced oxidation, adsorption, biological uptake, and ion exchange for their ability to achieve very low total P concentrations in high-flow systems. Adsorption appears to have the greatest potential for near-term implementation. Biological uptake and ion exchange show promise based on laboratory-scale research and may be long-term options. Pretreatment using advanced oxidation may be valuable in converting organic P to the more readily removable orthophosphate form. © 2013 Copyright Taylor and Francis Group, LLC.
Hibbard C.S.,Camp Dresser and McKee Inc.
Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA | Year: 2011
A discussion covers EPA's air emissions regulations for combustion sources, including biomass combustion for energy production and biomass conversion for fuels; how small changes in biofuel mix and type trigger differing requirements in EPA's combustion rules; how to obtain exemptions from these rules for bioenergy facilities through determinations that the fuel is not a solid waste, or determinations that the facility is a qualified small power producer or qualified cogeneration facility; and case studies illustrating how the Clean Air Act Section 129 rules for "waste" combustion and the Clean Air Act Section 111 and 112 rules for "traditional fuel" combustion can be applied to bioenergy facilities. This is an abstract of a paper presented at the 104th AWMA Annual Conference and Exhibition 2011 (Orlando, FL 6/21-24/2011).
Murphy L.J.,Camp Dresser and McKee Inc. |
Schoettle T.,Camp Dresser and McKee Inc.
Storm Surge Barriers to Protect New York City: Against the Deluge | Year: 2013
The Arthur Kill located between Staten Island to the east and New Jersey to the west is a commercial and recreational waterway that runs between Upper New York Bay and Raritan Bay. The information presented here considers the design of a storm surge barrier located across the Arthur Kill that would work in concert with barriers located on the East River, the Narrows, and Rockaway to protect the island of Manhattan from impacts of a Category 3 hurricane and its associated storm surge. © 2013 American Society of Civil Engineering.
McPherson D.L.,Alan Plummer Associates Inc. |
Charles T.J.,Camp Dresser and McKee Inc.
Pipelines 2010: Climbing New Peaks to Infrastructure Reliability - Renew, Rehab, and Reinvest - Proc. of the Pipelines 2010 Conference | Year: 2010
The nature of transient hydraulics in a pipeline system is often very difficult to identify and fully quantify. As a result, surge control strategy is often a compromise on providing the greatest benefit for the lowest cost while also considering the full range of alternatives and operational constraints. This may be difficult to do, especially with staged facility expansion that must address near and long term flow projections. Design often relies on a maximum flow rate that is identified as a "worst case" scenario surge control based on this assumption. However, these simplifications, when considered in a system with near and long-term projected flow rates, may be incorrectly defining the best surge control strategy, particularly if the highest projected flow rate is never realized. This paper will use case studies to compare two different approaches with regard to surge control protection while considering near and long term flow rates and the associated flexibility or lack thereof that is related to the surge control. Pros and cons will be discussed for each approach and discussion will be developed for reader consideration. © 2010 ASCE.
Sanderson J.S.,The Nature Conservancy of Colorado |
Rowan N.,Camp Dresser and McKee Inc. |
Wilding T.,Colorado State University |
Bledsoe B.P.,Colorado State University |
And 2 more authors.
River Research and Applications | Year: 2012
Growing water demand across the world is increasing the stress on river ecosystems, causing concern for both biodiversity and people. River-specific environmental flow assessments cannot keep pace with the rate and geographic extent of water development. Society needs methods to assess ecological impacts of flow management at broad scales so that appropriate regional management can be implemented. To meet this need in Colorado, USA, we developed a Watershed Flow Evaluation Tool (WFET) to estimate flow-related ecological risk at a regional scale. The WFET entails four steps: (i) modelling natural and developed daily streamflows; (ii) analysing the resulting flow time series; (iii) describing relationships between river attributes and flow metrics (flow-ecology relationships); and (iv) mapping of flow-related risk for trout, native warm-water species and riparian plant communities. We developed this tool in two watersheds with differing geomorphic settings and data availability. In one of the two watersheds, the WFET was successfully implemented to assess ecological risk across the 3400-km 2 watershed, providing consistent watershed-wide information on flow-related risk. In the other watershed, active channel change and limited data precluded a successful application. In Colorado, the WFET will be used to evaluate the risk of impacts on river ecosystems under future climate change and water development scenarios (e.g. for energy development or municipal water supply). As water continues to be developed for people, the WFET and similar methods will provide a cost-effective means to evaluate and balance ecosystem needs at large scales. © 2011 John Wiley & Sons, Ltd.
Patel A.,Camp Dresser and McKee Inc. |
Serrano S.E.,HydroScience Inc.
Journal of Hydrology | Year: 2011
The method of decomposition of Adomian is an approximate analytical series to solve linear or nonlinear differential equations. An important limitation is that a decomposition expansion in a given coordinate explicitly uses the boundary conditions in such axis only, but not necessarily those on the others. This paper presents improvements of the method that permit the practical consideration of all of the conditions imposed on multidimensional initial-value and boundary-value problems governed by (nonlinear) groundwater equations, and the analytical modeling of irregularly-shaped heterogeneous aquifers subject to sources and sinks. The method yields simple solutions of dependent variables that are continuous in space and time, which easily permit the derivation of heads, gradients, seepage velocities and fluxes, thus minimizing instability. It could be valuable in preliminary analysis prior to more elaborate numerical analysis. © 2010 Elsevier B.V.
Pekin O.,Camp Dresser and McKee Inc.
Geotechnical Special Publication | Year: 2010
Step-path slope failures in jointed bedrock are analyzed using the PCSTABL slope stability computer program. The model simulates bedrock as anistropic material with variable discontinuity lengths. Discontinuity lengths are varied by adjusting the number of boxes used in the BLOCK search routine. Bedrock discontinuity information is based on visual examination of rock cores and acoustic televiewer data. Anistropic strength parameters are obtained from direct shear testing of rock samples. Results provide an understanding of how slope factor of safety varies with slope direction and discontinuity length. The analysis methods are applied to a proposed 400-foot deep quarry in Central California. Slope stability evaluation is especially important in this case because a steep slope is desired for improved production, but the pit is located close to a highway and a canal. © 2010 ASCE.
Feng S.,Camp Dresser and McKee Inc.
7th International Symposium on Heating, Ventilating and Air Conditioning - Proceedings of ISHVAC 2011 | Year: 2011
Energy modelling is essential in the sustainable building design. The paper outlines how to use eQUEST as the energy modelling software to simulate the whole building energy performance and how to incorporate the simulation results in the building design and LEED™ (Leadership in Energy and Environmental Design) application. The study demonstrates that the energy modelling plays a key role in the integrated design approach in order for the designer to make the informed decisions that may impact building energy performance before the construction. The designer, contractor, owner, developer and occupant can benefit substantially from the energy modelling. The study also discusses common pitfalls of energy modelling in design projects.
Camp Dresser and McKee Inc. | Date: 2011-03-12
Disclosed are embodiments of a method and apparatus for the treatment of water containing silica in order to recover as much treated water from a water source as possible while minimizing the generation of waste products. Other embodiments include removing specific elements from the water source and utilizing those elements. Embodiments of the method and apparatus uses in-line physical and physio-chemical treatment methods to remove potential biological, colloidal and hardness foulants continually so that there is minimal loss of water from the water source stream and minimal addition of chemicals to accomplish removal or reduction of these potential recovery-limiting foulants.