Civil Engineering - Solid Waste
Municipalities throughout Washington State have called on BHC Consultants to provide the following Solid Waste services and solutions in response to a wide range of concerns and issues over the last decade. Below is a list of specific Solid Waste services offered:
- Engineering Feasibility Study/Report
- Construction Services
- Hydraulic Modeling
- Landfill Design, Closure and Reuse
- Leachate Collection and Treatment
- Landfill Gas Control Monitoring
Solid Waste Project Briefs
Anchorage Regional Landfill (ARL) Cell 10 Development, Municipality of Anchorage, AK
In 2009, the ARL was nearing capacity in its existing cell 7 and needed to develop a new cell. BHC was part of a consultant team hired to re-evaluate their existing site development plan to identify where the next cell should be constructed, design the cell, provide construction observation services, and assist with a variety of other operational issues. The project team met with the solid waste management and operations staff to review and assess operating practices and needs, and conducted a workshop which resulted in changing the planned cell development sequence. The workshop process also led to the decision to bid and construct Cell 10 in two contracts: a mass excavation contract, and a cell construction contract. Construction of both phases was completed by the fall of 2010.
Services during construction were provided for both phases. Because the contract went smoothly, significant budget was available under this contract to complete other services including design of piping modifications near the leachate lagoons to bypass blocked piping, and development of a cell sequencing plan to guide future cell construction through 2020.
Anchorage Regional Landfill (ARL) Cell 10 Development Leachate Clogging, Municipality of Anchorage, AK
As construction of Cell 10 was underway, a leachate clogging problem was discovered that required immediate attention. Leachate piping near the leachate lagoons had become completely clogged with calcite. A design solution needed to be developed quickly so that the Cell 10 contractor could construct the remedy as a change order to their contract. Working closely with operations staff, bypass piping was designed within a week, a change order was negotiated within another week and the piping was constructed and operational within 5 weeks of when the problem was discovered.
Anchorage Regional Landfill Cell 6 Development & Site Development Plan, Municipality of Anchorage, AK
BHC was part of a multi-disciplinary engineering team that provided planning, design, and construction management services for the development of Cell 6 at the Anchorage Regional Landfill.
BHC’s roles include evaluating leachate flows and pretreatment requirements, designing leachate and stormwater facilities as well as technical review of the project elements. The Cell 6 design also included preparation of a site development plan to guide future development of the landfill, refinements to the closure plan, and cost estimates.
Solid Waste Facility Planning and Operations Assistance, Carson City, NV
Since 2007 BHC has been assisting Carson City with various solid waste facility planning, design, and permitting efforts. Carson City owns and operates a solid waste landfill that receives waste from within the City and some neighboring counties. The City is considering making changes to its solid waste collection, processing, and disposal practices to increase recycling and improve operational efficiency. BHC has assisted the City during this process with the following efforts:
- Evaluate historical waste quantities and forecast future waste quantities – This effort was for MSW and C&D waste and considered changes expected from increased recycling and bringing in more waste from nearby counties.
- Landfill site development planning – Evaluated expansion into newly acquired property and developed conceptual plans for LFG, leachate, and stormwater control facilities.
- Transfer station conceptual layout and siting – Developed to improve landfill operations and prepare for more aggressive recycling activities.
- Procurement assistance for a design-build-operate contractor for a recycling and composting facility – Developed future waste quantity projection to use as baseline for evaluation, evaluation criteria, and rfp. Evaluated responses, recommended shortlist of companies for interview, participated in interviews, assisted City in development of design-build-operate contract.
Solid Waste On-Call Services, Douglas County, OR
BHC Consultants has performed several tasks for Douglas County at the active Roseburg landfill and closed Reedsport landfill under this on-call contract as follows:
- Develop phased filling plans through proposed final grades.
- Develop intermediate and final drainage plans identifying drainage improvements needed for various filling stages. This work included hydrologic and hydraulic analyses.
- Develop preliminary final closure section design and details of features to be provided with the final closure.
- Develop landfill gas control plans and details.
- Develop leachate treatment alternative concepts needed for discharge of leachate to the creek adjacent to the Roseburg landfill or the Umpqua River.
- Conceptual sizing of leachate treatment facilities and development of capital and operational cost estimates for Roseburg.
- Development of leachate pumping, storage, and conveyance facilities for conveying leachate to a neighboring WWTP.
Reedsport Landfill, Douglas County, OR
Douglas County, Oregon owns and manages the Reedsport landfill, a closed, municipal solid waste landfill, located near Reedsport, Oregon. The Oregon Department of Environmental Quality (DEQ) has mandated that the County develop a plan to improve the quality of leachate that is currently discharged from the landfill into Scholfield Creek. BHC is currently assisting the County in the evaluation of different leachate treatment processes to reduce iron and ammonium concentrations.
Roseburg Landfill Closure and Leachate Management, Douglas County, OR
BHC is currently assisting with the closure, including a leachate management plan, of a landfill outside of Roseburg, OR. Tasks include data collection and review, hydrologic and hydraulic analysis, and the development of a final grading plan for the site.
Unalaska Landfill - Cell 4 Development, Cells 1&2 partial closure and Phase II Expansion, City o f Dutch Harbor, AK
BHC is currently part of a project team assisting the City of Dutch Harbor, Alaska, with design and permitting for expansion of their landfill. In 2006, Phase I of the Unalaska Landfill was nearing capacity. Cell 4 was the final cell in the City’s current landfill development plan and the Alaska Department of Environmental Control (ADEC) questioned further expansion at the site due to its proximity to the ocean. Leachate from the landfill is pumped into the City’s wastewater collection system and thus to the City’s WWTP. The City’s WWTP was also over capacity and experiencing permit violations partially as a result of leachate. The project team prepared a Phase II landfill development and cell sequencing plan that would provide capacity through 2050. BHC evaluated existing leachate flows, and developed leachate flow projections. The study concluded that further landfill development would require flow leveling facilities and recommended measures to reduce leachate generation including phased closures and run-on control features. Design of Cell 4 and Cells 1&2 closure included systems to collect leachate weeps from an adjacent unlined waste area and convey them to the site leachate collection system. The project design team prepared preliminary designs for the first 2 cells of Phase II and leachate flow leveling and pretreatment facilities. A feasibility study of WWTP improvements was also prepared to identify what would be needed to bring the WWTP into compliance and to accommodate future landfill expansion and population growth. These documents were submitted to ADEC, EPA, and US Department of Justice to support expanding the landfill and negotiating new WWTP facility improvements and an NPDES discharge permit. ADEC agreed to permit the Phase II landfill expansion after submitting additional stability, beach erosion, and lining system equivalency demonstration studies. Final design of the first two Phase II cells and leachate management facilities is currently underway as is development of a WWTP facilities expansion plan, including on-site pilot testing for an evaluation of leachate treatability and chemically enhanced primary wastewater treatment.
Riverfront Development, Landfill Cover, Leachate Collection, and Landfill Gas Facility Design, City of Everett, WA
the Riverfront Development, portions of which are on the capped Everett Landfill Site. Specific facilities that BHC was responsible for designing are: Hydraulic and Landfill Gas (LFG) barriers, LFG collection trenches and modifications to the existing LFG blower system to be constructed as part of roadway improvements; leachate collection trench modifications to minimize ground water intrusion; and leachate pumping and conveyance facility modifications. The project includes significant coordination with City engineering and utility operations and maintenance staff. The project included existing refuse excavation and relocation within the project site to areas that will be covered by the landfill cover system. BHC also provided construction observation and management services.
Port Angeles Landfill Cell Stabilization Project, City of Port Angeles, WA
The Port Angeles Landfill originated as an open dump in a gravel pit west of the city on a bluff near the Strait of Juan de Fuca. Due to ongoing bluff erosion and migration, the bluff face is now in close proximity to the remaining refuse which would be at risk of falling onto the beach or into the Strait if bluff migration continues. BHC is part of a multidisciplinary design team tasked with eliminating the potential for refuse release to the environment in the 25 to 50 year planning horizon. BHC is responsible for design of landfill cover systems, leachate collection and conveyance systems, and refuse relocation procedures. Landfill cover systems designed for the project include a composite cover section in accordance with WAC 173-351 as well as systems that comply with the previous regulatory standard, WAC 173-304. The composite cover system will require a bentonite amended low permeability soil component. Refuse relocation procedures include methods for determining that soils remaining in the area where refuse has been removed comply with appropriate regulations.
Cedar Hills Regional Landfill Area 4 Closure and Area 5 Development, King County, WA
BHC Consulting provided civil engineering design services for the closure of Area 4 and development of a new 50-acre landfill cell (Area 5) at the Cedar Hills Regional Landfill. Services included the design and evaluation of both leachate collection and conveyance facilities and drainage management systems and conveyance facilities; assistance on the overall cell and closure system layouts; and design of construction and operation erosion controls.
A contaminated surface water lagoon and associated conveyance pipelines, manholes, and flow meters were designed to service Area 4 and future Areas 5, 6 and 7. Hydrologic and hydraulic analyses were performed to determine an appropriate size for the lagoon and the influent and effluent pipelines. Plans and specifications were produced for these facilities. Erosion and sediment control plans and specifications were also produced for the Area 4 closure. Construction services included on-site observations, submittal review and office engineering.
For development of Area 5, leachate and stormwater conveyance systems were designed to route leachate and stormwater from Area 5 to the existing leachate and stormwater conveyance facilities. An analysis of leachate generation rates and peak flows for all areas of the landfill was completed. Results of this analysis were used to model future leachate generation rates and peak flows for the landfill, including Area 5. The analysis determined whether the existing leachate and CSW lagoons provided enough storage volume, and identified operating requirements to prevent overfilling of the storage lagoons. Alternatives for conveyance of leachate and stormwater out of Area 5 were evaluated, including the use of forcemains, deep trench pipelines, and micro-tunnelled pipelines. A hydraulic analysis of the selected leachate forcemain and downstream conveyances was completed to identify needed improvements for these facilities.
After completing these evaluations, stormwater and leachate conveyance facilities were designed, including a triplex 50-hp pump station and forcemain for stormwater, and a duplex 34-hp pump station and forcemain for leachate. Improvements to existing leachate and CSW conveyance facilities were also designed to accommodate higher flows. Construction services included submittal reviews and production of pump station operation and maintenance manuals. Erosion and sedimentation control plans and specifications were also prepared for Area 5 and the main stockpiles for Area 5 development.
Cedar Hills Regional Landfill Area 6 Phase I Excavation and Phase II Development, King County, WA
As a sub-consultant, BHC Consultants has assisted in the development, preparation, and publication of reports, technical memoranda, and drawings to support permitting requirements, construction projects, and landfill operations. The work included Engineering Reports, Construction Bid Packages, Operations Plans, and Quality Assurance and Control Plans.
Phase I Excavation
BHC Consultants’ role in the design of the cell included 3-D modeling, planning for refuse placement, and modeling and design of collection storage, pumping, and conveyance facilities for contaminated surface water and leachate.
Phase II Development
BHC Consultants participated in value engineering reviews and construction meetings throughout the project and provided engineering services for the development of Area 6 at the Cedar Hills Regional Landfill. Additionally, BHC performed preliminary conceptual designs, analyses, and evaluations to determine the configuration and layout of the leachate and contaminated stormwater collection and conveyance systems, and evaluated the leachate lagoon aeration system. The work also included the development of preliminary concepts and BMPs for erosion and sedimentation control measures for the excavation and construction of Area 6 and the soil stockpile.
Cedar Hills Regional Landfill Area 5 Phase II Development and Area 5 Liner Over Unlined Refuse Area (A5LOURA), King County, WA
BHC Consultants assisted in the development, preparation, and publication of reports, technical memoranda, and drawings to support permitting requirements, construction projects, and landfill operations. The work included Engineering Reports, Construction Bid Packages, Operations Plans, and Quality Assurance and Control Plans.
The liner over unlined refuse was completed in 2002 and was immediately put to use. The A5LOURA was the first lining system permitted under WAC 173-351 by Seattle-King County Public Health and WSDOE to be constructed over an existing refuse mound that was previously unlined. Our role included the development of a leachate collection and conveyance system that was designed to accommodate anticipated local and global settlement of up to 20 feet.
Cedar Hills Regional Landfill Area 7 Closure, King County, WA
When completed the CHRL Area 7 closure project will be a 64-acre staged closure designed and permitted in accordance with WAC 173-351. The first of four closure stages was recently completed in the Fall of 2013. The subsequent stages of closure will be completed over the following four years. The closures will include both interim and final cover systems as well as; horizontal landfill gas collection trenches; separated stormwater and contaminated stormwater management and storage facilities. As prime consultant, BHC is responsible for overall management, design of cover systems, site civil work, and modifications to the Plan of Operations as well as construction observation services to assist the County Road construction management team with landfill cover system construction expertise.