Construct-Ability was engaged on the Pharr Lift Station No. 25 and 16” Force Main Improvements project to provide cost estimating and to provide our client with a constructability review to determine potential risks associated with the planned improvements and how they might affect project cost, timeline, delivery, etc. In our review, we noticed that the majority of the risk associated with this project was in bypass pumping while keeping the existing facilities on line during the construction of the new lift station components.
During our site evaluation process, we typically visit the site and take measurements and pictures to determine if the site allows enough space to build the proposed improvements and also to identify the issues with conflicts between existing and proposed components. We realized that the existing lift station site did not reach all the way out to the property boundaries, so we notified the client that there was valuable space that wasn't being utilized. The proposed lift station could be configured differently on the property, affording the contractor the ability to utilize the existing lift station facilities during construction of the new lift station and associated structures. This would reduce the efforts required by the contractor during bypass pumping. Per the original plan, the contractor would have to bypass 100% of the flow of 5.1 million gallons/day through a temporary lift station for an extended period of time because the construction of the new lift station would require another substantial effort using a driven pile system in a sandy subsurface. By using the extra space, we could reduce the project's cost; the contractor wouldn't have to dig up existing pipelines and re-route them out of the way while bypass pumping the entire time, and decreasing risk factors inherently decreases cost.
The pipeline portion of the scope looked straightforward. The most risk associated with the pipeline was in the aerial crossing of the ditch with the force main as there were no drawings indicating what was to be done for this scope. The other risk we identified was traffic control; we would be laying the pipeline along a busy street with schools on both sides. The timing of the pipeline installation would determine just how much risk would be associated with the pipeline. If we could avoid the school season, we could potentially lower our traffic control costs.
We included all of our contract document findings and detailed descriptions of each potential problem in a report with aerial maps snapshots of the affected areas under consideration. We recommended a solution for each problem we identified within the contract documents. Our team also included a cost estimate for both the proposed force main and the lift station.
Once the cost estimating portion of our project involvement was complete, we moved to the project sequencing and scheduling of our scope. Here we began to piece the project together. Using the assumed production rates and crew sizes, we determined how long the project should last and identified key components with long lead times. Mitigating long delays from long lead times allows us to shorten the overall project duration considerably, which in turn reduces project costs due to reduction in overhead costs.
Our team also provided numerous alternative layouts for the electrical panels and ductbanks in order to eliminate the need to demo structures prior to having the new lift station on line to reduce the bypass pumping efforts. Overall, we reduced the project budget by 28%. This allowed the project to continue through design, and it has been through the bid process.