Title
Discuss and consider a report on issues recently discovered at the Lake Pflugerville Pump Station and authorizing City Manager to procure services and equipment for the emergency repairs necessary to return the pump station to full working condition.
Summary
On Thursday morning, May 1, 2014, utility staff employees doing a routine check of the Lake Pflugerville Pump Station observed large amounts of water bubbling up through the ground around the building. This pump station pushes water from Lake Pflugerville to the City's Water Treatment Plant. Without this pump station in operation, the water treatment plant has no water to treat.
The leaks were significant enough that we had to discontinue use of the pump station. To assure that Pflugerville customers had water, we opened and closed valves around the City so that we could serve the entire City with our two water wells. We contacted Manville and they agreed to temporarily suspend taking water from the City under our two wholesale agreements with Manville. They were currently taking 1.5 million gallons per day, which accounted for 25 % of the water we produced on Wednesday of this week. We also contacted the ESD and requested that they avoid any hydrant flow testing or any exercises that would use large quantities of water. We instructed our construction inspection department to ask the city's capital improvement plan (CIP) contractors and subdivision developers to not flush any water lines under construction until next week. By making these requests, we were able to fully serve our retail water customers at this time with well water only.
Significant water was present along the west side of the building as well as in vaults to the south of the building accessing the discharge pipe connecting the pump station to the water treatment plant. Because of the critical role of this pump station to our ability to provide water, we treated the investigation and repair of this facility as an emergency. The size of the pipes (up to 48" in diameter) connecting to this pump station and the depth of the pipes (up to 22' deep) are beyond the capabilities of our Utility Department Staff to repair.
Status Report
Utility staff procured a utility contractor to assist the City in the emergency response to get the pump station repaired. Hansen Contracting, LLC, a Pflugerville utility contractor, was contacted to take the lead in repairing the water problems. This work began Thursday morning. We were not able to isolate which pipe was the source of the leak until very late Thursday night. It turns out that there were multiple pipes leaking. The pipes in question appeared to be the pipes leading to the three pump cans and are also the deepest pipes at the pump station. These pipes are 22' deep to the bottom of the pipe and extend about 14' under the building. Because of the late hour and needing to bring in larger excavators to dig 22' deep, we stopped work and began again at 7 a.m. on Friday morning.
Excavation to reach the pipes took 18 hours because of the depth and because the ground was super-saturated with water requiring a lot of pumping of the excavation area. Approximately 800 cubic yards of dirt were removed in 18 hours. We began to work our way along the pipe looking for leaks. We did not find the leaks until we reached the pump cans 14' feet under the building. That was about 7 a.m. Saturday morning, May 3, 2014
The pipe pump cans had only been protected from corrosion (rust) by a manufacturer applied coating. There were 6 holes rusted through the pipe, some as large as an inch in diameter. To get the pump station partially back in operation, we placed a separate pipe repair sleeve over each of the holes. This was successful, and we now have one pump working at the pump station. Completing this task, we sent the contractor and our crews home to get rest. They had worked 33 hours straight since Friday morning. The contractor and our support crews were back on the job site Monday morning to complete the excavation to expose the two remaining pump cans. We know that at least one of the two remaining pump cans has holes in it as well.
We believe the 3 existing pump cans are beyond repair, and our temporary repairs on the one may not last very long. The pump cans will have to be installed from under the building and will also require removing the 3 pumps while the replacement is being done.
We need to fully investigate what changes need to be made to the design and corrosion protection of the new pump cans so that this problem will not be repeated. The city engaged the engineering firm of Freese and Nichols, Inc. to assist the city in investigating the causes of the corrosion failure of the existing pump cans, to develop the design and specifications for the replacement pump cans, to assist the City in procuring the replacement pump cans and a contractor for the installation, and to be available during construction to assist in resolving any technical issues. Freese and Nichols is a very qualified engineering firm in the utility engineering field, with a wealth of experience in pump stations. They are available and began working with us on Monday, May 5, 2014.
Our crews public works crews from both the utility and street departments and the contractor's personnel performed in an amazing way over the last 3 very long days, and we can be very proud of what was accomplished. Even with all the issues and setbacks, the staff worked hard to assure that every customer had water and service was not interrupted.
Deadline for City Council Action
This is an emergency item and approval is necessary for staff to move forward with repairs.
Fiscal Impact
The costs of this emergency situation will be funded through utility fund balance and included in the proposed budget amendments for the third quarter of fiscal year 2014.
Staff Recommendation
Staff requests authorization of the ongoing expenditures used to procure services and equipment for the emergency repairs necessary to return the pump station to full working condition.
Drafter
Tom Word
Assistant City Manager