Water Operations Construction Newsletter

Volume 2, No. 6 | August 2022

Monthly Update

Welcome! This is our monthly Water Operations capital project newsletter for Commission employees. Each newsletter will provide construction project updates and information about the upcoming work at our drinking water assets and facilities.

If you want to learn more about a specific project or have feedback/suggestions, contact James Laurila at james.laurila@waterandsewer.org

or Christina Jones at christina.jones@waterandsewer.org.

Clearwell construction at West Parish Filters

What’s on the Horizon for Water Operations?

The Commission is embarking on large-scale upgrades to its drinking water infrastructure. Commission water infrastructure ranges from 50 to over 100 years old, and much of it is in need of rehabilitation or replacement due to its age or inability meet regulatory requirements. The Commission has also been periodically out of compliance with the regulatory limits for disinfection by-products. We have identified several cornerstone projects to complete in the next 5-7 years to address these needs, including a new clearwell and backwash pumping station (construction underway), a new conventional water treatment plant with dissolved air flotation as a clarification process, and rehabilitation of the 42-inch raw water pipe and new hydropower infrastructure.

August Highlights

The following projects have progressed over the months of August:

Clearwell & Backwash Pump Station - CH Nickerson continued construction of the clearwell, hydraulic control structure, and influent control vault.

New Underdrain for Rapid Sand Filter #6 - RH White completed installation of the Filter #6 underdrain system. WPF staff installed the filter media and recommissioned the filter, and it is now back online.

RH White is nearing completion of the Bulk Chemical Storage and Chlorine Improvements project, which includes constructing a new bulk storage system for our ACH coagulant chemical and replacing elements of our gaseous chlorine system. In August the gaseous chlorine system improvements were completed and brought back online. The temporary sodium hypochlorite system is no longer in use.

Water Operations crews completed cleaning the plant's ten Slow Sand Filters at an accelerated pace. The filters were relied on heavily this year as a result of the RSF Filter failure and needed to be cleaned to meet peak summer demands. Thanks to their hard work, SSFs 9, 10, 11-14, and 15-18 are all cleaned and ready for service. The SSFs are currently able to be offline because the capacity of the rapid sand filters has been restored.

Clearwell & Backwash Pump Station Project Highlights

Why are we building it?

The new Clearwell and Backwash Pump Station will replace the existing clearwell and backwash, domestic, and process water pumps. The existing clearwell was originally constructed as a slow sand filter in the 1920's and the roof leaked into the clearwell until we installed the temporary tarp cover. Failure of this clearwell would require the Rapid Sand Filter Plant to be shut down entirely. The existing backwash pumps were installed in the 1970's with the construction of the Rapid Sand Filter Plant and need to be replaced. Parts for these pumps are no longer available should they require repair. This new Clearwell and Backwash Pump Station structure will provide the reliability and redundancy needed for the water treatment process and is the first component of the new water treatment plant.

Completing the Clearwell Structure

CH Nickerson continued working on sealing and testing the Clearwell structure over the month of August. As is standard practice with this type of structure, the crew identified cracks in the structure and injected sealant in each crack to prevent water from leaking out.

Once the structure is complete and has passed water tightness testing, construction of a pump station directly over the Clearwell will begin. The pump station walls are scheduled to be erected in October.

Clearwell structure

(Drone photo by SWSC)

Crew installs sealants

(photo by SWSC)

Hydraulic Control Structure

(photo by SWSC)

Clearwell (far left) and the Hydraulic Control Structure (center bottom)

(Drone photo by SWSC)

Filter #6 Underdrain Installation

RH White completed installation of the Leopold block-style underdrain system in Rapid Sand Filter #6 (RSF#6) in August. The new system replaced the old clay tile system that was original to the 1970's plant and that failed in January.

The filter underdrain block system was designed by AECOM in February and March. After being awarded a contract the new underdrain system was ordered by RH White. While waiting for its delivery, RH White demolished the failed underdrain.

Once the new block system was delivered to the plant, the crew began prepping the blocks by installing protective covers on them to prevent damage and contamination during installation.

Leopold Block-Style underdrain components

(photo by SWSC)

Crew taped covers on blocks to protect during installation (photo by SWSC)

Grout was installed in the empty filter to level out the base for the blocks. The crew then began installing the blocks, using grout to affix them to the bottom of the filter. Each block was snapped into the adjacent block.

Once the blocks were installed, the crew poured grout between them and in the remaining spaces underneath them to completely affix the blocks to each other and to the floor of the filter.

Empty filter ready for block installation

(photo by SWSC)

Crew installing the blocks

(photo by SWSC)

Once the blocks were installed, the crew carefully removed the protective covers and cleaned up dust and debris.

After installing, crew removed protective covers and cleaned the blocks (photo by AECOM)

An Empty Bed Test was performed to test the blocks prior to installing the filter media.

Empty Bed Testing (photo by AECOM)

The Water Operations Labor Staff re-installed the filter media, which consists of sand and anthracite. The media was disinfected and the filter was restored to service.

Empty filter with block system installed

(photo by AECOM)

Filter media installed

(photo by AECOM)

Filter #6 online (photo by SWSC)

What's Next?

The following projects are in construction or are in the design pipeline:

In Progress:

Clearwell/Backwash Pump Project -

Tighe & Bond and C.H. Nickerson (the Design-Build team for the project) is completing sealing and leak testing the Clearwell structure and hydraulic control structure and will begin constructing a pump station on top of the Clearwell. This project will replace our existing clearwell and the rapid sand filter backwash pumps.

ACH Bulk Storage/Chlorine Building -

RH White has nearly completed constructing a new bulk storage system for our ACH coagulant chemical and replacing elements of our gaseous chlorine system. The gaseous chlorine system is back online and the ACH system is scheduled to return to service in September.

Coming Up:

WTP Design - Hazen completed an alternatives analysis for several critical decisions and is continuing design of the new water treatment plant.

Hydropower Plan - Due to issues with establishing utility connection with Eversource, the Commission has stopped plans for a proposed inline hydropower project on the 42-inch raw water main. We have contracted with Kleinfelder/Stantec to complete an assessment of the Cobble Mountain Hydrostation and make recommendations for plant improvements.

Upper Lagoon Dam #2 - Tighe & Bond is evaluating options for repairing or removing Dam #2, as a result of the slope failures that occurred in August. We are also working with Hazen to determine if the upper lagoon will be needed as part of the new water treatment plant.

42-inch Raw Water Transmission Main - We are continuing to review the options to repair or replace the 42-inch main in order to provide reliable raw water delivery redundancy for years to come.

a peek back in time...

Train used to move excavated materials for the Ludlow WTP, 1906

SWSC Employee Website