How is Compost Made?

The TDSL compost site is one of the largest conventional windrow and static pile composting operations in Texas. The facility encompasses over 30 acres, where approximately 18 acres are used as compost pad surfaces, with specific areas for feedstock receiving, active windrow composting, curing, screening, wood waste grinding, and product storage. The design and construction meet the TCEQ’s 30 TAC Chapter 332 Composting Rules construction requirements under the “Registration Tier” level of regulation and is fully authorized under TCEQ Permit #2123 to protect the underlying groundwater and storm water run-off. Although a 25-year storm event pond is required by the state, a 100-year storm event pond was designed and installed. Paved working areas and the storm water retention pond are compacted to meet the state requirements of having the hydraulic conductivity of two (2) feet of clay compacted to a permeability coefficient of 1 x 10-7 cm/sec or less.

Materials come into the compost site when diverted from the TDS Landfill at the gatehouse or Citizen’s Convenience Center for use by Texas Organic Products (TOP). The raw materials which will be included in the compost are called feedstock, and include yard trimmings and brush; clean, untreated wood waste; produce; paper; animal byproducts; oils and greases; and some liquid, such as dairy materials, beer, wine, soft drinks and other beverages. The materials are sorted and either stored or ground and then stored. The materials are combined according to specific recipes and added to long rows, called windrows and static stockpiles. After forming into compost windrows, temperatures of 110 and 150 degrees Fahrenheit are typically achieved within a week. After composting for two to three months, the material is placed in piles for curing, followed by screening to remove larger woodchips and foreign materials greater than 3/8-inch diameter, which go back through the windrow process. In the windrows, the materials breakdown and beneficial microorganisms further process the materials into rich compost. The compost is stockpiled and screened, and finished compost is then bagged or sold in bulk for use in gardens, lawns and landscapes to provide essential nutrients to plants. 

The TDSL compost site is constructed of approximately one million cubic yards of clay soil excavated from a cell expansion of the TDS Landfill, thereby making good use of soil that would otherwise be stockpiled or hauled off-site. The design also includes a visual berm that was planted with grass to maintain an aesthetically pleasing appearance from the highway while blocking the view of the operations.