To: Honorable Mayor and Members of Town Council
From: Mark Marlowe, P.E., Utilities Director
Jeanne Stevens, P.E., Engineering Manager
Title
Resolution: Approving an Equipment and Services Acquisition Agreement with AWI-Anthratech U.S., Inc. for the Ray Waterman Regional Water Treatment Center Underdrain/Filter Cell Replacement Project
Body
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Executive Summary
The Utilities Department is seeking Town Council approval of a resolution (Attachment A) awarding an Equipment and Services Acquisition Agreement (Exhibit 1) with AWI Anthratech U.S., Inc. (AWI), for the Ray Waterman Regional Water Treatment Center (RWRWTC) Underdrain/Filter Cell Replacement project. The AWI project cost is $553,500 for the planned major modifications to the RWRWTC involving the removal and replacement of filter underdrain assemblies and filter media from all eight filter bays. Staff also requests approval for a 10% staff-managed contingency, $55,350, for a total project authorization of $608,850. This authorization request exceeds the project’s 2015 budget amount but is less than the total amount budgeted of $1 million for the project over 2015 and 2016. Additional funds available in a separate account will be transferred to make up the difference, with no net change in the 2015. Staff plans to complete the project over the winter when the treatment plant can be taken offline and have the facility back online for the spring 2016 irrigation demand season. The issues with the plastic underdrains are such that replacement is necessary to ensure we maintain long term filtering of high quality and reliable drinking water.
A consideration of life cycle costs indicates that replacement of the plastic underdrain now with the AWI stainless steel system is the most beneficial approach. Previous experience with AWI solving this same issue at the Founders Water Treatment Plant (FWTP) was very good and the costs for this project provided by AWI are the same eight years later.
History
Utilities staff presented the specifics of this project to the Utilities Commission at their regularly scheduled meeting held on July 22, 2015. The presentation highlighted the scope and complexity of some of the larger capital improvement projects (such as this proposed project) that Utilities project managers complete. These types of projects support the goals of our vision and mission ensuring reliable, high-quality drinking water is distributed to our community. Utilities Commission voted to recommend Council approve this project.
Discussion
The Utilities Department is planning a major modification to the Ray Waterman Regional Water Treatment Center (RWRWTC) involving the removal and replacement of filter media and filter underdrain assemblies from all eight filter bays. Utilities is planning to work exclusively with AWI-Anthratech U.S., Inc., who performed the same services 8 years ago when Utilities rehabilitated the Founders Water Treatment Plant (FWTP). A sole source justification form has been completed (Attachment B). The existing filter underdrains were installed during construction of the RWRWTC in 2005 and are manufactured of a plastic material. The plastic underdrains have slotted openings on the top that function to collect filtered water and to distribute water and air used for backwashing of filters. During typical filter run times the filtered water collects in the underdrain, is conveyed through the effluent piping to the clearwell, and is then ultimately pumped into the water distribution system.
Above the underdrain assemblies are seven layers of varying sizes of graded gravel. Gravel is designed to support the overlaying filter media, which consists of a 24-inch deep layer of greensand and an 18-inch deep layer of anthracite. In addition to supporting the filter media, the gravel was designed to prevent the smaller filter media (greensand and anthracite) from settling to the top of and passing through the slots of the plastic underdrain.
For about five years Utilities has been dealing with the fact that the filter media systems and underdrain assemblies at the RWRWTC have not been performing at the level desired and the smaller filtering media is passing through the gravel base and into the underdrains. From the underdrains the media flows into the filter effluent piping and ultimately settles in the clearwell. In 2010 and then again in 2013, Operations staff completed the difficult task of removing approximately 21,500 pounds of media from the effluent pipe and clearwell (see Attachment C, Pictures 1, 2, & 3). A replacement cost for this media is approximately $6,500.
To begin the cleaning project Operations staff needs to disassemble a 15 foot high metal weir box with frame assembly that is anchored to the concrete basin wall. Staff then use a ladder to access the 42-inch diameter influent piping located about 8 feet off the floor. Staff climbs into the piping and begins the laborious process of shoveling media from a prone position into a wheeled bucket. As the piping is cleared, staff shimmies up the pipe filling the bucket. When the bucket is full it is pushed to the opening and dumped back down to the floor. Containers at the floor level are filled and carried to beneath an access hatch. A truck mounted crane is used to haul the media filled containers to the surface. Staff labor associated with each cleaning equates to approximately $16,500. There has been no reoccurring loss of media at the FWTP, and we expect the same improved operations at the RWRWTC. This current underdrain rebuild project will remove the safety risks to staff and the maintenance costs associated with cleaning the clearwell of media.
Additional media has been added to the top of the filters to maintain effectiveness for removing iron and manganese from the raw deep aquifer groundwater, but the underdrains continue to allow media to pass through. The inefficient filter operations and these non-sustainable maintenance procedures could lead to water not being properly treated in the future. The worst case event is that the underdrains will plug with media and prevent filter flow all together.
A durable long lasting underdrain and media system is critical to proper and efficient operation of a conventional groundwater treatment facility such as the RWRWTC. The Town’s FWTP is a similar conventional groundwater treatment facility using sand and anthracite media to filter the raw groundwater. In 2007, Operations staff completed an optimization study to improve operating efficiencies at the FWTP. Media was also collecting in the clearwell at this facility and the underdrains were determined to be plugging with media. At that time, we worked with nationally recognized engineering consultants who specialized in optimizing hydraulics and overall performance of this type of water treatment facility. They determined that a complete retrofit of the filters at the FWTP was the best course of action and recommended Utilities work with AWI. The filter rebuild at the FWTP in 2007 ensured a properly functioning facility that most importantly produces potable water that more reliably meets or exceeds all applicable water quality standards and has been maintenance-free since being replaced.
AWI are industry leaders with a proven track record in the field of fabricating and installing stainless steel underdrain systems. The AWI panel system eliminates the need for gravel base layers that are more prone to disruption and failure from their intended purpose. For the FWTP Project, we worked with AWI and negotiated an agreement to remove and replace the existing media and underdrain system. Although AWI completed installation of new media, it proved to be most cost effective for the Town to purchase new media directly from suppliers, and we again plan for the same course of action for the proposed RWRWTC filter retrofit project. Demolition of existing facilities is an extremely labor intensive work activity that AWI completed in a timely manner and on budget for the FWTP (see Attachment C, Picture 4). They worked with us to keep the project on track even when the unexpected was encountered during rebuild operations. AWI also provided professional engineering assistance during the facility startup phase. Since the FWTP rebuild, there has been no reoccurrence of media depositing in the FWTP clearwell, and the facility has performed as expected and efficiently for the past eight years. The same crew leader that installed the FWTP underdrain system would also be working in the field on the RWRWTC filter retrofit project.
Today there are other companies that manufacture somewhat of a similar underdrain system when compared to the AWI system. However, the AWI system does have substantial advantages over these other designs. For example, the identical AWI underdrain system being proposed for the RWRWTC project has been successfully installed and continues to operate in over 1,500 filter basins. This number of filter basins equates to more than 630,000 square feet of underdrains in service for over 15 years. The current AWI lateral design is a single unit welded design constructed of stainless steel. Other vendor designs rely on bolted assemblies to secure their media retention systems to their lateral design. AWI no longer produces this design because they found the interior bolts loosened over time causing areas of failure in the ability for the underdrain to retain media. The AWI stainless steel media retention system (see Attachment C, Picture 5 for the system installed at FWTP) is self-cleaning, provides a high resistance to plugging, and is manufactured in the USA. In addition, every AWI underdrain system is custom designed to the filter dimensions, the method of operation, the hydraulic requirement, and the raw water quality the filter is treating. Utilities anticipates another successful filter retrofit project with AWI.
AWI was selected for this project based on Utilities’ past experience with them on the FWTP project, their proven success in this very specialized field of design and construction, and the value they bring to ensuring high quality drinking water. The project with AWI for the FWTP (including demolition, design and furnishing underdrain, and installing new underdrain system) in 2007 cost approximately $230 per square foot (total square footage was 720). This proposed project with AWI for the RWRWTC will also cost approximately $230 per square foot (total square footage is 2,400). We are benefitting from some economies of scale and realizing a similar cost per square foot some eight years later. An additional cost comparison involved the rebuilding of four of the Meadows Water Treatment Facility (MWTF) filters. The existing plastic underdrains were removed along with the media and replaced in-kind. The same plastic block underdrain was reinstalled so the rebuilt filters would match the hydraulic characteristics of the four other existing filters (added with facility expansion project) that did not need rebuilding. The MWTF filter rebuild project cost approximately $240 per square foot. Regarding expected service life of underdrains, plastic block underdrains have a serviceable life expectancy of about 20 years and the AWI stainless steel system is about 40 plus years.
AWI’s proposal for the RWRWTC underdrain/filter cell replacement project is $553,500 and includes design and manufacturing of the stainless steel underdrains for all eight filters at the RWRWTC, removal of existing gravel and filter media, demolition/removal/disposal of existing underdrains, and installation of new underdrains with new filter media, and facility startup assistance upon completion. Utilities expects the same quality and value from AWI that we have successfully experienced in the past.
In fact, the total project cost, assuming no unexpected issues, will come in below the $1 million budgeted for the total project between 2015 and 2016.
Budget Impact
Utilities budgeted $500,000 in 2015 and $500,000 in 2016 for this project (Water Fund Capital Projects account 210-4275-442-77-95 RWTP Filter Media Upgrade). AWI’s proposed fee is $553,500. Staff requests an additional $55,350 (Town managed 10% contingency) be authorized for a total project authorization of $608,850. Because this exceeds the 2015 budget appropriation, a budget transfer will be completed to the RWTP Filter Media Upgrade account in the amount $167,000 to cover the shortfall of $108,850 in the 2015 budget. The remaining $58,150 from the budget transfer will be used for additional project expenses related to media testing for disposal and the pre-purchase of replacement media, which may have a long lead time for delivery. There will be no net increase to the Utilities’ budget as a result of this budget transfer.
Proposed Motion
I move to approve a Resolution Approving the Equipment and Services Acquisition Agreement for the RWRWTC Underdrain/Filter Cell Replacement Project.
Staff Recommendation
Staff recommends Town Council approval of the resolution approving the Equipment and Services Acquisition Agreement for the RWRWTC Underdrain/Filter Cell Replacement Project with AWI-Anthratech USA, Inc. in the amount of $553,500 (Attachment A).
Attachments
Attachment A: Resolution
Exhibit 1: Agreement
Attachment B: Sole Source
Attachment C: Project photos