R.F. MacDonald Co. provides turnkey solution and long-term pump system reliability for moving contact pond water in green waste decomposition process
Solid Waste Site
Bay Area, CA
Pump System Design and Installation
In Northern CA, a solid waste and environmental solutions company creates an organic compost product by using green waste collected from curbside bins that have been ground to approximately 1.5-inch pieces using a Covered Aerated Static Pile (CASP) process for decomposition and pathogen reduction.
Covered: The compost is covered with green waste.
Aerated: Air is added through holes in the floor.
Static Piles: The compost pile is unmoving.
Liquid management is critical to the process and involves water in contact with green waste in a closed-loop system.
The CASP process encourages organic decomposition and requires an initial addition of water containing common bacteria and fungi.
First, contact water is sprayed to inoculate the freshly ground material, which kick-starts the decomposition process. Excess contact water, not absorbed by the material, is then captured, and allowed to flow back to the contact water pond where it is stored. Finally, the contact water is pumped back to the CASP located at an elevation of 80-feet above the pond to repeat the process.
The R.F. MacDonald Co. Analysis & Solution
The solid waste site had been using rental diesel pumps, which utilized a prime assist feature with foot valves added on as an aftermarket upgrade. The foot valves were necessary to stop the suction lines from flooded during shutdown. However, the large amounts of fine organic solids caused the foot valves to continually clog and fail.
Additionally, the lack of circulation in the CASP pond allowed the contact pond water to become stagnant, which was producing unwanted odors for the surrounding community.
After excessive pump maintenance and downtime, the pumps were deemed too expensive and unreliable. An economic and permanent solution was required with the desire to use the site’s self-generated electrical power.
Based on a history of success with the customer, R.F. MacDonald Co. was asked to develop a permanent, turnkey pumping solution with full system reliability. The turnkey solution provided by R.F. MacDonald Co. includes pumps, piping, controls, fabrication and complete installation services.
- Piping: Experienced technicians installed 280 feet of 4-inch high-density polyethylene pipe (HDPE).
- Electrical: Certified controls experts replaced the existing VFD with a new control panel on a newly poured 8-inch concrete pad.
- Fabrication: Skilled pump experts designed and built custom pump stands to easily move the pumps and withstand a corrosive environment.
R.F. MacDonald Co. provided three heavy duty pumps sourced from Toyo-Hevvy. The transfer process uses two pumps as part of a multi-stage design to move the pond water, a light-slurry, uphill to the CASP. The third pump provides circulation within the contact water pond.
One Toyo-Hevvy HNS submersible pump generates 600 GPM at 127 feet of TDH to boost the light-slurry pond water 22 feet uphill to the booster pump. Choosing a submersible lift pump eliminated the challenge of keeping the suction lines flooded. It also generates ample suction at the booster pump.
The Toyo-Hevvy HNH booster pump generates an additional 127 feet of TDH, pumping over another hill to the CASP green waste pile.
The third pump is a circulation pump, which discharges through 280 feet of HDPE in the shape of a giant T with nozzles located at the ends. This helps evenly circulate the product throughout the pond, which has greatly reduced the amount of odor.
The new pumping system has met all performance expectations. Both boosting and circulation applications have been working reliably without fail since startup in December 2020.
R.F. MacDonald Co. is proud to offer reliable pumping solutions for the recycling and green waste decomposition process.
Contact R.F. MacDonald Co. to help select the best pumps and pumping solutions for your liquid handling needs.
PDF: Solid Waste Site Uses Booster & Circulation Pumps to Move Light Slurry for Green Waste Decomposition