The Edward Farrar Utility District(EFUD) is in the process of obtaining Statements of Qualifications from qualified engineering firms detailing the firms’ qualifications, technical expertise, management and staffing capabilities, references, and related prior experience. Required professional services will include at this time feasibility study level engineering services. The feasibility study, may in the future, lead to preliminary engineering, final design- and construction-related services, preparation of bidding and contract documents, participation in the evaluation of bids received, and monitoring and inspection of construction activities to ensure compliance with plans and specifications associated for the Edward Farrar Utility District WWTP Sludge Management Plan. A WWTP History, Purpose of the Feasibility Study, Proposed Project Team and Feasibility Study Scope of Work are below.
Procurement of said services will be in accordance with elements of the procurement process in 40 U.S.C. § 1101-1104. Qualified firms/candidates interested in being considered for this project must submit five (5) hard copies and one electronic copy each of: (1) letter of interest; (2) statement of qualifications and experience of staff persons who will be involved with the project; (3) references; (4) related prior experience and (5) location of office where work on the project will be conducted. It is important for each firm to clearly show experience with the Feasibility Study Scope of Work. Submit the requested information to (28 North Main Street, Suite 1, Waterbury, VT 05676); no later than (4:00 P.M.) on 28 March 2022 in order to receive consideration.
Attention is directed to the fact that the proposed project may be undertaken with a variety of Federal and state funds and that all work will be performed in accordance with the regulations issued by such agencies and the State of Vermont pertaining thereto.
The EFUD shall evaluate the statements of qualifications and performance data and other material submitted by interested firms and select a minimum of three firms which, in their opinion, are best qualified to perform the desired services. Interviews with each firm selected may be conducted, which may include discussions regarding anticipated concepts and proposed methods of approach. The EFUD shall rank, in order of preference, these three professional firms deemed to be the most highly qualified to provide the services required, and shall commence scope of services and price negotiations with the highest qualified professional firm for engineering services.
The original Edward Farrar Utility District (EFUD) WWTP, located along US Rte 2 west of Waterbury Village, was constructed in 1978 and replaced an extended aeration package WWTP located in the Village. Design flow was 0.51 MGD. The WWTP included three (3) aerated lagoons followed by a chlorine contact tank and a control/laboratory building. WWTP effluent is discharged to the Winooski River. Approximately 16 acres of farmland surrounds three sides of the lagoons where lagoon sludge is periodically land applied.
In 2014 the WWTP was upgraded to meet the Lake Champlain TMDL for phosphorus removal. Design flow remained at 0.51 MGD. The upgrade included the construction of a ballasted flocculation treatment process-so called CoMag. The process utilizes magnetite to enhance removal of the chemical floc. The CoMag Building includes the CoMag process train (feed pumps, three reaction tanks and clarifier), magnetic drum, chemical storage and feed systems (PAC, caustic soda and polymer) two sludge holding tanks with mixers and a rotating drum thickener (RDT) with associated polymer system and eight (8) covered sand drying beds with a sludge storage bunker. Waste chemical sludge (WCS) is removed from the clarifier and pumped to a magnetic drum where magnetite is separated from the WCS and returned to the reaction tanks. The WCS flows from the magnetic drum to the sludge holding tanks. Since 2014 the WWTP has routinely met the effluent phosphorus limit and the CoMag chemical process also enhances BOD and TSS removals. The staff, early on, determined that the CoMag process worked best when operated at the design flow of 0.51 MGD. Currently influent flows average around 1/3 of design flow. With the advantage of having the 3 lagoons upstream to attenuate and store influent flow the staff operates the CoMag process for 3-4 days at design flow and then turn off the CoMag process letting the lagoons fill to a predetermined level before restarting the CoMag process.
In recent years three Grid Bee slow speed mixers have been added to the lagoons (two (2) in Lagoon 1 and one (1) in Lagoon 2). The addition of the Grid Bee mixers has allowed the staff to reduce the number of aerators and thereby reducing power costs. The remaining aerators provide the needed dissolved oxygen and the Grid Bee mixers augment the mixing.
With the concerns on land application of WWTP sludges becoming more prevalent, staff have recently added a sludge removal barge on lagoon 1 to remove sludge on an annual basis instead of conducting a land application of lagoon sludge onto the WWTP farmland as has been done in the past. Concurrently with the barge operation staff have begun adding an enzyme to the lagoons which is purported to reduce sludge buildup. The sludge removed from Lagoon 1 by the barge operation has been placed onto two of the eight drying beds for dewatering.
Currently the CoMag and lagoon sludges, after drying on the sand drying beds, are co-mingled and stored in the sludge storage bunker until the sludges are trucked to Englobe for disposal.
Purpose of Feasibility Study
Since the CoMag process was put into operation, sludge management problems have developed:
- Waste chemical sludge (WCS) from the CoMag process, as noted above, is stored in two 79,000 gallon sludge storage tanks (SST). Periodically the SSTs are decanted and the decant is returned to Lagoon 1. The Basis of Design envisioned, at design year flows of 0.51 MGD, pumping 7200 GPD of WCS to the SSTs. Currently the WCS wasting rate averages between 15,000-25,000 GPD depending on seasonal algae and lagoon conditions, which obviously fills the SSTs quicker than anticipated in the design. Under current operation the SSTs are undersized.
- As the SSTs fill with WCS the WCS sludge has been pumped to the RDT for thickening and the thickened WCS (TWCS) pumped to the drying beds for dewatering. If the RDT thickened the TWCS to more than 2-3% the TWCS would not flow over the surface of the drying beds but remained in piles below the discharge pipe. The RDT has been a continual maintenance problem and has never consistently produces a thickened sludge, regardless what % solids the staff were trying to achieve. Staff have recently stopped running the RDT and now directly pump SST WCS directly to the sand drying beds. With wetter WCS than anticipated in the design there needs to be more sand drying beds.
- The piping system between the SSTs and the sand drying beds do not allow for winter pumping. As the WWTP goes through winter WCS builds up in the SSTs and eventually the decant includes WCS returning to Lagoon 1. This adds to the sludge buildup in Lagoon 1.
- With the Lagoon 1 barge pumping sludge to one of two sand drying beds the shortage of sand drying beds is compounded further.
- The Lagoon 1 barge system cannot operate in the winter.
- Recently EFUD has contemplated adding one additional (25’ W X 100 ‘ L) sand drying bed (which is twice the surface area of one of the existing sand drying beds. However, this does not address the undersized SSTs or necessarily add sufficient sand drying bed area to keep up with both WCS and lagoon sludges.
- Rather than simply building an additional sand drying bed EFUD has now decided to stop and consider all options to develop a long term sludge management plan starting with a feasibility study.
Proposed Project Team
The proposed project team for the Feasibility Study (and hopefully beyond) will be:
- Town of Waterbury/EFUD Public Works Director William Woodruff
- Town of Waterbury/EFUD Engineer Alec Tuscany
- EFUD WWTP Chief Operator Peter Krolczyk
- EFUD WWTP Operator Matt Jones
- Ray Pepin-Senior Process Engineer (recently retired from Evoqua, current marketer of CoMag) with 50 years’ experience in wastewater treatment. Ray was instrumental in CoMag startup and subsequent CoMag operating issues
- Selected Consultant
Scope of Work
The proposed scope of work for the Feasibility Study centers on developing a long term sludge management plan and shall include but not be limited to:
- Get Start Meeting with Project Team
- Tour of WWTP site with emphasis on how WWTP currently operates
- Review Historical Data
- Stantec Basis of Design
- WWTP Operational Data (from CoMag startup in 2014 to present)
- EFUD staff generated O&M Manual
- WWTP As-builts and changes since CoMag 2014 startup
- Identifying site limitations for additional structures
- Past and current sludge management issues
- Effectiveness of enzyme to reduce sludge production in the lagoons
- Identify Possible Sludge Management Alternatives such as:
- Increase effectiveness of enzyme addition or other additive(s) to Lagoons to further reduce sludge production
- Modify CoMag process to reduce quantities of WCS
- Enhance SST decanting system to reduce solids return to Lagoon 1 including modifying the inadequate telescoping valves
- Modify WCS pumping system to allow for year round drying bed applications
- Continue land application of lagoon sludges for all three lagoons or only Lagoons 2 and 3
- Modifications to Lagoon 1 barge system to include piping from Lagoons 2 & 3
- Add additional sand drying bed(s) with/without translucent roof
- Remove some or all sand drying beds and replace with
- Contract dewatering of either or both lagoon sludge and WCS
- Add in-house mechanical dewatering (filter press, centrifuge, etc) for either or both WCS and Lagoon sludge
- Conversion of some drying bed(s) to house dewatering equipment and more storage bunker space
- Decommission and possibly remove RDT
- Various combinations of all above
- Other Alternatives
- NOTE: while current influent flows average around 1/3 of design flow and for the foreseeable future, probably will be in the 1/3 of design flow, all alternatives considered need to be based on the design flow of 0.51 MGD
- Rank alternatives considering feasibility level construction costs, O&M costs, man power requirements, site constraints, permitting issues, potential funding sources.
- Prepare a Feasibility Study Report summarizing all work, findings and recommendation(s) on “best” alternative
- Feasibility Study report to be completed by end of 2022.
Contact William Woodruff, EFUD Public Works Director