Reno County Municipal Solid Waste Landfill Facility, Hutchinson, Kansas
Background
The Kansas Dept. of Health and Environment, Bureau of Air and Environmental Protection Agency regulations necessitated a landfill Gas Collection and Control System (GCCS) expansion for the area of Cell 5 to comply with state and federal policies. These regulations require a GCCS installation at applicable municipal solid waste units within five years of the first placement of waste in cells.
Efforts for installing the expanded system took several years of coordination between SCS and Reno County. First, the County had to build a new cell so that waste placement operations could move away from the proposed construction area in time. SCS developed construction drawings for a new cell (Cell 7) in early 2016, and construction was officially complete in November 2016.
Challenge
The landfill GCCS construction schedule needed to coincide with Reno County operations as well as meet a November 1 deadline to comply with Environmental Protection Agency regulations. While in the design phase, surface emissions data resulted in exceedances and, therefore, a timeline to replace four existing wells moved the deadline for installation up three weeks. The system expansion required 8 new extraction wells, 4 replacement extraction wells, a 600-ft horizontal collection pipe, and 2,600 feet of HDPE pipe installed by October.
Design
Once a new cell is built, development takes several months before the County can begin full operations into a new cell. Therefore, SCS and Reno County had to plan well in advance of the gas system construction. Once operations moved to Cell 7, SCS surveyed the ground surface in the old cell (Cell 5) in order to calculate the total proposed well depth and to assess pipe routes.
Engineering efforts consisted of calculating pipe lengths, pipe diameters, well depths, vacuum pressures, and development of design details. However, this project was more than just engineering documents for a typical design‐build project. SCS along with subcontractors worked closely with Reno County to both design and build this gas system expansion. Teamwork and good communications facilitated the installation and successful activation of the expansion within the compliance deadline.
After determining the optimal locations for the LFG wells, an active cell survey facilitated an optimal layout of the gas collection pipe network. SCS determined the total depth of the wells, created calculated pipe losses and requirements, developed well schedules, and finalized details based on project requirements, survey data, and historical as-built drawings.
Construction
Construction efforts were not without challenges. During construction, SCS trenched into and managed excavated waste; some trenches were as deep as 14 feet. High winds created an additional challenge in managing the excavated waste. Fusing and placement of long runs of HDPE pipe were demanding. Coordinated efforts and construction crew synergy were key to efficient pipe installation and gas well connections.
Outcomes and Benefits
The County and SCS teamwork was a major factor in the GCCS completion 10 days prior to the expedited deadline. The expanded network officially opened to the gas collection system on October 3, and the Agency notified of the construction and the official beginning of operation in a semi-annual report.
Accomplishing a design-build around an active landfill area takes experience and a multi-faceted team of experts to execute the solution effectively. SCS provides this and added efficiencies in the design, construction, and contract management. The team was able to streamline the design and construction processes to realize significant cost savings without sacrificing performance, such as running pipe at a minimum 3% slope to avoid deeper waste excavations and a higher cost. SCS’s experience helped meet the challenges of integrating with the existing system, waste excavation, and leachate management.
Safety is paramount to any construction project, especially on a landfill. In addition to typical personal protective equipment, the construction team made use of explosive gas meters, steel grates, and fall protection.
