LAMB CANYON SANITARY LANDFILL (LCL) - PHASE 2, STAGE 4 EXPANSION
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Description
The LCL is an active municipal solid waste disposal facility (Class III Landfill) and operates in accordance with the Waste Discharge Requirements (WDRs) issued by the Regional Water Quality Control Board (RWQCB), and the permit requirements issued by the California Department of Resources Recycling and Recovery (CalRecycle) and the South Coast Air Quality Management District (SCAQMD). In conformance with the WDRs, all new waste containment cells must be lined with clay and a composite geosynthetic liner system for the protection of the ground water from contaminants such as leachate and gases produced by the decomposed refuse.
Prior to this project, the existing refuse disposal area at the LCL was comprised of a lined area (referred to as Phase 2) and an unlined area (referred to as Phase 1). The subject project expanded the landfill into an approximately 21 acre area, referred to as Phase 2, Stage 4 (P2S4), creating a 400–feet wide floor (on average) and steep slopes graded generally at an inclination of 1.5:1 (horizontal to vertical) with intermediate benches about 20 feet wide spaced every 50 vertical feet. Total slope heights for this project varied from 20 feet to about 180 feet. The project started in March 2013 and was completed and approved for use by the RWQCB in January 2014. The total cost of the project was approximately $11 million dollars, which was approximately 1% below the contract amount.
This landfill liner expansion project included mass earthwork excavation and construction of a composite liner system in the canyon floor and on the side slopes. The project included the following items of work:
1. Mass earthwork excavation consisting of 1.57 million cubic yards of soil material within an approximate 50 acre area
2. Engineered fill slope of 342,000 cubic yards
3. Stockpiling of 1.25 million cubic yards of soil material to serve as a daily refuse cover source
4. Processing and placement of 17,300 cubic yards of low permeability clay liner
5. Placement of 21 acres of composite geosynthetic liner system (10 acres on the canyon floor and 11 acres on the side slopes)
6. Installation of 4.6 million square feet of multiple layers of liner material (Geosynthetic Clay Liner, High Density Polyethylene, Geotextile Fabric)
7. Placement of 13,000 cubic yards of ½” minus gravel (leachate drainage layer)
8. Installation of 3,000 feet of high density polyethylene pipe and three 10,000-gallon tanks (leachate collection system)
9. Construction of approximately 19,000 linear feet of surface drainage improvement structures, including grouted rip-rap, shotcrete, asphalt concrete pavement, corrugated metal flume down drains and pipe culverts
10. Construction of 900 linear feet of 50-ft wide asphalt concrete access roadway
11. Construction of a water quality sedimentation basin consisting of approximately 23 acre-feet holding capacity and a basin discharge system and an emergency spillway to handle Q100 = 320 cubic feet per second.
It should be noted that project design, contract documents (plans and specs), and construction management were all completed in-house by RCWMD engineering staff.
