Keeping Service Impact and Construction Sequence in Mind

Keeping Service Impact and Construction Sequence in Mind

OCTOBER 14, 2021

We often tackle upgrades to aging drinking water infrastructure, including pump stations. However, each project presents its own unique challenges for our engineers to overcome. One southern California agency serving approximately 100,000 residents hired Woodard & Curran to design and perform construction administration for upgrades to six pump stations scattered across its large service area with a myriad of challenges. First, none of the pump stations were the same in terms of rating, size, layout, condition, or equipment. Second, all new equipment needed to fit in the limited confines of the existing structures. And third, as integral facilities within the agency’s drinking water distribution system, the stations could not be off-line for extended periods of time as reliable water service needs to be maintained. 

Incorporating potential challenges during design

Most of the pump station equipment targeted by this project was near the end of its useful life. Parts for this aging equipment were increasingly difficult to source, and even when available, vendors had increasingly long lead times. With pumping capacity of the stations ranging from just over 1 million gallons per day (MGD) up to 13 MGD, the improvements were necessary to mitigate the risk of failure and extended outages, which would compromise the agency’s ability to deliver reliable potable water to its customers. 

To create the most accurate and safe design, our team reviewed all available as-built documentation and conducted a thorough field investigation to identify space and other potential constraints that might impact the sequence of work and project schedule. Our team performed a laser scan of the building and equipment at each pump station, which provided additional detail on the existing condition of assets and allowed us to generate 3D models. By leveraging this 3D modeling technology, our design team had precise information on the location of existing pumps, piping, electrical equipment, conduits, and other physical space constraints, which proved critical for the specification and design of new equipment to fit within the existing physical constraints at each facility. The 3D models not only became the basis of design drawings, but also were critical in developing construction sequencing to limit downtime at each pump station. This attention to detail will mitigate potential change orders during construction, which will result in time and cost savings, as well as limit equipment downtime and unplanned shutdowns. 

The design team also assessed the demand conditions within each pressure zone to inform minimum pumping capacity required to maintain service during construction. While some of the pump stations could go offline for three to five days, others needed to remain functional in some capacity throughout the duration of construction because distribution storage would not adequately provide water for fire protection. At each of the six pump stations, the design team developed a contingency plan including portable generators and motor control centers connected to a minimum number of pumps, as well as other temporary equipment that could be operated in case of an emergency. 

Through a series of workshops, our experts engaged stakeholders in the decision making. Specifically, the agency’s operations team provided input on functionality and constructability, as well as insight regarding supply outages and minimum parameters for maintaining flow to the distribution system during construction. The workshop and design review process ensured all feedback was incorporated, which is just another means to ensure the project stays on schedule and on budget. 

Providing a total solution

This project is just one example of how our experts provide clients with total solutions beyond planning and design, including constructability, regulatory compliance, and ease of operation and maintenance. Our approach to project management supports this philosophy by providing consistent communication with the client and coordination with various stakeholders, vendors, and contractors. We pay particular attention to operations staff, as their institutional knowledge is critical to developing sound solutions that accomplish the necessary work while minimizing impact on existing water system operations.

Author

National Practice Leader
Drinking Water

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Donna Rammell, Senior Technical Manager & Kyle Tracy, Senior Technical Practice Leader
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