City of Wichita Falls
Wichita Falls Landfill, TCEQ Permit No. MSW-1428A
Wichita County, Texas

Overview
Biggs and Mathews serves as the City’s consulting engineer for design, permitting, construction, and compliance issues related to its solid waste programs. The City received authorization for a permit expansion that added significant disposal capacity to the landfill in 2003.  Biggs and Mathews prepared the expansion permit application and has completed numerous projects relating to the design and construction of new cells and closure of cells.  All aspects of the design and construction phases of each project were coordinated by Biggs and Mathews including cost estimates, approving quantities and pay requests, approving shop drawings, approving project element scheduling.  Groundwater monitoring, landfill gas perimeter monitoring, surface water monitoring, and construction of leachate monitoring at the site are all performed by Biggs and Mathews.  

Professional services provided included installation of landfill gas monitoring probes and groundwater monitoring wells.  Engineering design projects have included development of soil borrow plans, sequence of development plans, perimeter drainage construction documents, and air quality permitting.  The sequence of development was designed to provide the City of Wichita Falls in excess of 15 years of disposal capacity before the next landfill cell will be required.  Ongoing projects include soil management, airspace optimization, and site development engineering.

Permitting
Biggs and Mathews provided subsurface characterization, environmental analysis, hydrogeologic characterization, a Conditional Letter of Map Revision (CLOMR), and engineering design for expansion of the City of Wichita Falls Landfill.  The expansion was a horizontal and vertical expansion of the existing landfill and increased the permitted area to 564 acres, the waste disposal footprint to 352 acres, and the remaining disposal capacity to 76 million cubic yards.  This expansion provided over 150 years of disposal capacity to the City of Wichita Falls and surrounding areas. The permit was issued by the Texas Commission on Environmental Quality (TCEQ) on August 14, 2003.  In addition to the landfill expansion permitting, Biggs and Mathews also prepared several permit modifications and air quality permitting projects including standard air permitting, emission rate calculations, Tier 2 testing, and Title V permitting.

Construction Documents and Technical Specifications
Since 1994, Biggs and Mathews has provided engineering design and construction phase services for multiple Subtitle D cells, final closures and various site improvements at the Wichita Falls Landfill.  The Subtitle D construction projects included approximately 60 acres of Subtitle D liner and leachate collection system, approximately 22 acres of Subtitle D final cover system, a leachate pumping and transfer system, a contaminated stormwater evaporation and storage pond, and other miscellaneous improvements to the landfill. Ground survey and airspace calculations are conducted periodically to assist the City with cell construction and final cover scheduling.  

Construction Management
Biggs and Mathews provided construction management services for the various landfill cell and final cover construction projects. Services included conducting the bid advertisement and award phase, construction bid evaluation, and recommendation of award. Construction phase services include review and approval of shop drawings, field orders, change orders, construction quantities and pay requests, approving interim and final scheduling of the various construction projects.

Geology and Hydrogeology
Biggs and Mathews geologists and hydrogeologists completed comprehensive geologic, hydrogeologic, and groundwater characterization in support of the initial Subtitle D groundwater monitoring program at the Wichita Falls Landfill and for the 2003 permit amendment. In addition an alternate liner design was completed and approved by the TCEQ. Contaminant pathway analysis was used to design a groundwater monitoring system.  During the implementation of Subtitle D requirements, location restriction certifications for fault areas and seismic impact zones were prepared by Biggs and Mathews geologists following the completion of a site-specific fault study.

In response to the 2006 TCEQ rule revisions to Subchapter J – Groundwater Monitoring and Corrective Action, Biggs and Mathews prepared a Groundwater Monitoring System Demonstration and permit modification to show that the existing system meets the requirements of the revised rules for groundwater monitoring well spacing.  The facility groundwater monitoring system that was approved in 2003 was re-evaluated including identification and evaluation of the following criteria:  the uppermost aquifer, groundwater flow direction and rate, potential impacts of operational attributes of the facility on groundwater flow using MODFLOW and MODPATH groundwater modeling software, impacts to critical receptors, appropriate spacing, locations, and screened intervals of groundwater monitoring wells.  In addition, a permit modification was completed for the facility’s Groundwater Sampling and Analysis Plan to bring it into compliance with the new rules.

Environmental Services
Biggs and Mathews provided installation of groundwater monitoring wells and landfill gas probes after issuance of the permit expansion. Groundwater monitoring including sampling, analytical laboratory testing, and statistical analysis has continued since issuance of the permit.  Additionally, Biggs and Mathews provided leachate management services including design and installation of dedicated leachate sump riser water level indicators.

Landfill Planning and Engineering Services
Biggs and Mathews provides extensive landfill planning and engineering services for the City including landfill capacity evaluations, preparation of required regulatory reports and assistance with TCEQ Air Permitting testing and reporting requirements.

Landfill Gas Services
While the Wichita Falls Landfill does not yet have a gas system, Biggs and Mathews has provided the City of Wichita Falls with life of site GCCS design and budget planning services, as well as LFG remediation services.

Drone Services
Biggs and Mathews has collected drone aerial topography data at the Wichita Falls Landfill for the purpose of estimating airspace consumption and waste settlement rates.