What is CASP?

CASP stands for Covered Aerated Static Pile. We’ll go into details below, but in a nutshell, that means it’s designed to provide optimal composting conditions through positive aeration, automatic irrigation, advanced temperature control, and a biofilter layer. Northern Recycling’s CASP was engineered and designed by Engineered Compost Systems located in Seattle, WA.

• Covered: The compost is covered with a biofilter layer made of mature compost or wood chips. It captures air emissions and controls odors. The biofilter cover also insulates and retains heat evenly across the pile. Heat is important during composting in order to help the material break down, as well as to kill weed seeds and pathogens.

• Aerated: Aeration is the process of adding air into the compost. With CASP, air flows upward via 6,336 holes installed throughout the concrete floor. The forced aeration helps the decomposition process, odor control, and keeps the process aerobic.

• Static Pile: The fresh material is built in a pile that is static during the “active” phase (unlike traditional windrow composting which requires turning of the pile). All of the automated aeration, irrigation, and hourly temperature feedback take place and ensure the decomposition process occurs efficiently.

How does CASP work?

1. Organic materials, including yard trimmings, food scraps, ground wood, grape pomace and agricultural waste are processed through a state of the art green waste processing line for size reduction and contamination removal. These materials are blended and loaded into CASP.

2. The biofilter cover (mature compost or wood chips) is applied on top of the fresh material to control any odor or emissions.

3. Air and water are automatically added to the compost to ensure ideal composting conditions.

4. After approximately 20-30 days in the actively controlled phase, compost is moved to another area where it can cure in the open (unaerated) for approximately 40-50 days.

5. After curing, the compost is done in a total of approximately 60-80 days! The finished compost is screened for quality and sold for use as a soil amendment in agriculture (vineyards, farms and orchards), landscaping and home or community gardens.

More on the details of composting at YCCL

Aerobic Compost Facility: 

The covered aerated static pile (CASP) facility is designed to provide optimal composting conditions via positive aeration, automatic irrigation, advanced temperature control, and a biofilter layer. In July 2022, YCCL and Northern Recycling opened a new state of the art Aerobic Compost Facility that will have an annual throughput capacity of 182,000 tons of organic waste. The CASP facility ensures adequate oxygen reaches the material via aeration, which flows upward from the concrete floor to the top of the pile. The biofilter insulates and retains heat evenly across the pile, guaranteeing proper temperatures are reached to kill weed seeds and pathogens. Automated aeration, irrigation, and hourly temperature feedback transforms traditional composting, giving operators greater control of the decomposition. The biofilter layer, which is made of mature compost or wood chips and covers the entire surface of each pile, captures air emissions and controls odors. Controlled aeration ensures aerobic decomposition.

Anaerobic Compost Facility:

Organic material (yard waste, food waste, and food soiled paper) is also handled at the Anaerobic Composting Facility (also located at the YCCL).  This facility handles 52,000 tons of green waste, food waste, and other organic waste each year through a combination of anaerobic digestion and aerobic composting operation.  The first phase (20 to 22 weeks) is anaerobic composting (without oxygen) which degrades non-woody organic wastes and creates methane, which is collected for the on-site electric generation power plant.  The second phase is aerobic composting (with oxygen) that degrades the remaining organic material aerobically (at least 2 weeks).  After the completion of the aerobic composting phase, the material is screened to remove non-compostable fraction and oversized material.