Town of Cary
North Carolina

Staff Report

Bid Award - South Cary Water Reclamation Facility Centrifuge


Category:Bid Award

Speaker:  Jamie Revels, Utilities Department


Executive Summary:  To improve efficiency while maintaining economies of scale in purchasing power, North Carolina General Statutes allow municipalities to purchase off another jurisdiction's previously bid contract (“piggybacking”). In applying this exemption to competitive bidding, the Council must approve the purchase at a regular meeting after a notice to waive the bid procedure has been advertised for at least 10 days. A contract was recently awarded by the City of Charlotte to Polydyne, Inc. (Polydyne) within the past 12 months, for thickening and dewatering polymer, an essential component of biosolids processing. By leveraging the contract unit price received by the City of Charlotte, the Town of Cary can continue its excellent biosolids process performance at a competitive contract price. 


Recommendation: That Council approve the use of the Waiver of Bidding for Previously Bid Contracts statute under NCGS 143-129(g) to award a contract to Polydyne for the purchase of Clarifloc SE 757 polymer at the price of $0.755 per pound until the contract term ends on August 22, 2020. The recommendation of award by Council represents a preliminary determination and not a legally binding acceptance of the bid. The offer is not valid until the Town has executed a Purchase Order.


Background: The Thermal Biosolids Drying Facilities located at the South Cary Water Reclamation Facility provide a sustainable and innovative approach to biosolids management by producing Class A, Exceptional Quality biosolids that are beneficially marketed for reuse as fertilizers and soil conditioners. The SCWRF thermal biosolids drying facilities began in November 2005 and continue to dewater and thermally dry biosolids produced by the North Cary and South Cary water reclamation facilities. Polymers are used in the dewatering process to enhance mechanical thickening and dewatering achieved by high speed machines known as centrifuges, which are used to increase solids content from 2.5% to approximately 20% solids prior to thermal drying. Polymer addition improves flocculation (clumping) of solids, which enhances the separation of solids from water during the high-speed centrifuge operation.  Solids are separated and sent to the drying process while centrate or residual wastewater removed from the centrifuge dewatering process is returned to the head of the plant for wastewater treatment.    


image003P1010001Andritz Centrifuges at SCWRF


Centrifuges at the SCWRF thermal drying facilities have treated between 31 to 33 million gallons of biosolids per year and required an average of 180,000 pounds of bulk polymer to support thermally drying biosolids into 3,300 to 3,500 dry tons of heat dried pellets for sale to agribusiness applications. The Polydyne polymer, sold under the trade name, Clarifloc SE 757, also meets South Cary Water Reclamation Facility (SCWRF) process and performance specifications for enhancing biosolids thickening and dewatering performance. This polymer has been thoroughly tested and used at SCWRF for the last 5-years.


Discussion: Town policy and NC governmental procurement laws ensure equity for vendor access to government contracts by establishing a competitive process for the purchase of supplies greater than $90,000. These practices are also designed to facilitate cost effective government operations based on an expectation that competitive pricing results in lowest cost. The purchasing statutes also recognize that further efficiency in time and staff effort can be realized through governmental partnerships such as joint agency bidding and "piggybacking" onto another jurisdiction's competitive bidding process. Council approval is a part of the statutory procedure for piggybacking to provide effective representation, transparency, and accountability for purchase of these chemicals by demonstrating the use of a bid process, in this case, managed by the City of Charlotte. The Town of Cary benefits from capitalizing on the combined purchasing power of a much larger contract to provide greater efficiency, lower costs, and ensure consistency for Class A, Exceptional Quality biosolids processed for marketing.


On February 26, 2018, the City Council of Charlotte formally approved a contract with Polydyne for a term of March 23, 2018 through August 22, 2020 with an option to renew for two additional two-year terms to supply their polymer at $0.755 per pound with no additional fees or fuel surcharges to the purchaser (see Attachment 1: City of Charlotte Polymer Contract). Previous contract pricing provided to the Town was $0.770 per pound, also from a previous Charlotte bid award using the piggybacking exception. Staff contacted Polydyne and they are willing to supply the polymer under the same price and terms as that of the City of Charlotte (see Attachment 2). The bid tabulation for the City of Charlotte is attached for reference (see Attachment 3). Staff reviewed historical usage of this polymer product and determined that centrifuge usage for the past four fiscal years averaged 180,000 lbs. per year while processing biosolids from SCWRF and NCWRF. The product quality of Cary’s pelletized biosolids are sensitive to changing inputs and conditions, which emphasizes the importance of maintaining consistency in the dewatering process.


Fiscal Impact:

Operating: The current contract purchase price set forth by the City of Charlotte purchase contract with Polydyne is $0.755 per pound. Based on annual polymer usage of 180,000 pounds, the Town of Cary can maintain current cost and production estimates under the City of Charlotte’s bid award pricing.


Funding: A total of $171,000 had been appropriated in the FY 2019 budget for centrifuge polymer expenses. Application of the Piggybacking statute under NCGS 143-129(g) will allow the unit cost of polymer paid by the Town of Cary to be fixed at $0.755 per pound until the contract term ends on August 22, 2020. This bid award supports current budget planning levels through 2020.


Next Steps: Execute a Purchase Order with Polydyne pending Council approval.