STANTEC CONSULTING SERVICES, INC. (4)

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need to address and mitigate PFAS compounds at —all affected, and even unaffected —well sites. Pairing this urgent need with the lingering effects of a disrupted supply chain, and the City's ability to produce its own water may be impacted for a significant time. During the detailed design phase, Stantec will work with equipment vendors and material suppliers to help determine the availability and lead times of critical design features. With this information and an anticipated construction sequence, we will incorporate the most available materials to minimize potential delay in the overall construction schedule. Stantec will also develop detailed construction sequencing and duration requirements within the technical specifications to provide the City with as much control as possible over the schedule. This will help reduce the amount of time the City may need to import water while a well (or group of wells) are not operational during construction. Designing for Operabilty, Cartridge Filters Prior to treatment, IX filters require removal of suspended solids from the raw water to avoid blinding the media bed, which extends the life of the media. Industry standard is a prefiltration process with five micron rated filters. This filtration step will be accomplished using horizontal, high - flow cartridge filters, which provide the following benefits: Horizontal orientation allows for ease of access and change out of filters at chest height, protecting operator safety and reducing the time required per change out Access at ground level eliminates the need for raised platforms, reducing cost, and maintenance Significantly reduces Mass to be removed number of units, as higher At the completion of the detailed design phases, Stantec will provide the City with a complete set of bidding and CDs for advertising to contractors. Bidding Phase To promote a timely and successful bidding process, it is imperative that the City, with the design team's assistance, respond to all inquiries promptly and thoroughly. This provides the bidders the most possible time to review bidding documents and addenda to prepare an accurate bid with as little ambiguity as possible. To accomplish this, Stantec would record and document all questions posed during the pre -bid meeting, as well, as all questions submitted via other channels. An addendum (if needed) would be created and issued, with the City's input, within one week of the pre -bid meeting. The need for additional addenda would be determined after this point and would be expedited to as much as practically possible. dfe-cycle costs The number and size of cartridge filters are designed to evenly distribute flow between filters, while providing the capability for N+1 redundancy at each site. Cartridge filters are preferred in lieu of bag filters as they offer a higher surface area, reducing the rate of increase in differential pressure, which effectively increases their dirt holding capacity between exchanges. Our example of life -cycle cost analysis is shown below. The labor is significantly reduced based on number of filters and ease of replacement (horizontal vs. vertical) resulting in a better value to the City for a life -cycle efficient design. ��• ee a e., Ibs 300 300 300 300 flow housings, reduce Dirt holding capacity each filter, Ibs 20 25 0.5 1 construction costs, and Cost per filter $200 $200 $3 $3 improve efficiency of filter - -- change out Filters per housing 15 15 25 25 All filters use the same Number of changes 1.0 0.8 24.0 12.0 cartridge filter element, — — allowing for ease of Change out time (hours) 3 3 6 6 purchase, storage, and Rate/hour $75 $75 $75 $75 replacement for all sites Piping will be routed With labor: Cost per lb $10.75 $8.60 $42 $21 underground, improving Without labor: Cost per lb $10 $8 $6 $3 access Note Information from Fil-trek Corporation (a supplier who provides both bag and cartridge filter equipment) was used in this analysis. City of Santa Ana On -Call Engineering Design Services for PFAS Treatment Systems RFP NO. 22-133 12