Mohammad Sharif Environmental Engineer, EIT
CV
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Active Class III MSW landfill — new lined cellComplete

Woodville Landfill — Southern Phase Cell Expansion

Design, and construction quality assurance on parts of the build, for a new lined disposal cell at Tulare County’s Woodville Landfill: capacity for a county that is consolidating its landfills.

Client / program
Tulare County Resource Management Agency — Solid Waste
My role
Design team & CQA support
Dates
2024 — 2025
Location
Tulare County, CA
Status
Complete
Pacific
Ocean 40° N 35° N 120° W
Woodville Landfill Tulare County, CA 36.10° N 119.20° W
Fig. 1 Key map. Position shown to about 10 km; drag to turn the ground.
Fig. 2 Woodville from the air

Problem

Tulare County is consolidating its landfills at Woodville, and the site’s permit required disposal there to resume by July 2024. That meant a new lined cell, built to keep waste and leachate out of the groundwater beneath a farming valley.

Approach

Our team designed the cell, a composite liner of reinforced GCL and 60-mil HDPE under a geocomposite leachate collection layer, and provided CQA on parts of its construction, checking the work in the field against the design.

Outcome

Phase 1 of the new unit, about 33 acres of lined cell, built in 2024 and ready to take waste: new capacity at the County’s main landfill.

The film above follows the cell from the air, cut from drone footage taken on site in May and June 2024: the prepared subgrade beside the existing landfill, the geosynthetic liner going down panel by panel, a pre-dawn night shift under light towers, crews deploying the geomembrane, and the finished scale of the lined cell. The score is original, composed for the film. It ends on the ground, with me and a colleague at the car the flights were flown from; other identifiable people, plates and signage were left out or blurred.

Setting

The Woodville Landfill is Tulare County’s Class III municipal solid waste landfill, in the San Joaquin Valley between Tulare and Porterville, and the site the County is consolidating its disposal into. Its first unit had stopped taking waste in 2014; under its Waste Discharge Requirements (Central Valley Regional Water Quality Control Board Order R5-2022-0027), disposal had to resume by July 2024. Resuming meant new lined space.

That space is Unit II, about 66 acres south of the existing unit, to be built in phases. Phase 1, roughly 33 acres, is the cell in the film. The County awarded its construction in late 2023, and it was built through the spring and early summer of 2024, against that deadline.

Our role

We were the designer of the southern phase cell expansion, and we provided construction quality assurance (CQA) on parts of its construction: carrying the cell from drawings and specifications into the field, and checking it was built the way it was designed.

The design

A cell is a system of layers, each with a job. From the bottom up, Unit II’s floor is:

  • engineered subgrade, graded so everything above it drains the right way;
  • a reinforced geosynthetic clay liner (GCL), a thin blanket of bentonite clay that swells into a seal when wet;
  • a 60-mil HDPE geomembrane over it, the two together forming the composite liner: the barrier between waste and groundwater;
  • a geocomposite drainage layer, the leachate collection and removal system (LCRS), carrying any liquid that reaches the liner to collection pipes in drain rock and out to be pumped;
  • and a two-foot operations layer that protects all of it from the first lifts of waste and the equipment that places them.

The side slopes carry the same composite liner, with a textured geomembrane for grip, anchored in a trench cut along the crest. Where the new cell meets the old unit, a separation liner and a landfill-gas pressure-relief system keep the two apart.

This layering is an engineered alternative to the prescriptive liner in CCR Title 27: it has to be shown to protect groundwater at least as well, it has to satisfy the Regional Board, and a contractor has to be able to build it, at scale, in a San Joaquin Valley summer.

The build

The photos on this page follow the construction: the floor graded and rolled ahead of the liner; GCL and geomembrane panels pulled off rolls on spreader bars, overlapped and seamed across the floor and up the slopes; drain rock pushed out over the liner and placed around the leachate collection pipe; and crews working on through the night under light towers.

CQA follows every layer: subgrade grades and compaction before anything covers them, material certifications and conformance testing for each roll, panel layout, seaming and seam testing, repairs, and the drainage layers above, all recorded so the owner and the Regional Board can accept the cell.

Seeing both sides, the design and the field, shows where a drawing meets real ground and real equipment, and that feeds straight back into designs that are easier to build well.

Skills demonstrated

Landfill cell design; composite liners with GCL and HDPE geomembrane; leachate collection and removal systems; Title 27 engineered alternatives; construction quality assurance on geosynthetics and earthwork; and carrying a design from drawings through construction against a permit deadline.

FiguresFrom the site

Fig. 3 Liner layers laid in bands across the cell floor, with the side slopes already covered.
Fig. 4 The new cell from its rim: liner going down across the floor, the existing landfill beyond.
Fig. 5 The lined side slope running down into the cell floor.
Fig. 6 The graded cell floor before lining, below the existing landfill.
Fig. 7 The prepared cell floor, seen from the haul road along its edge.
Fig. 8 The subgrade across the cell floor, graded and rolled ahead of the liner.
Fig. 9 Across the prepared floor to the lined side slopes and the crew's staging area.
Fig. 10 The cell from its corner ramp: prepared floor, lined slopes and the crew's vehicles.
Fig. 11 Drain rock stockpiled on the liner, ready to spread over the collection layer.
Fig. 12 A track loader pushing drain rock out over the liner.
Fig. 13 Placing drain rock around the leachate collection pipe.
Fig. 14 Drain rock along the toe of the lined slope, with the crew at the collection trench.
Fig. 15 Sunset over newly deployed geomembrane, its wrinkles catching the light.
Fig. 16 Seamed geomembrane panels across the floor and up the slope at dusk.
Fig. 17 A crew deploying a liner roll from a spreader bar on a telehandler.
Fig. 18 Pulling a new panel off the roll, overlapping the one beside it.
Fig. 19 Panels laid across the cell floor with marked overlaps, running up to the lined slope.
Fig. 20 Walking the deployed panels on the cell floor.
Fig. 21 A trench cut along the crest of the side slope, where the liner's edge is anchored.