Winton Overpass Piping Project
In 2016 Hayward staff undertook a “first-in-Hayward-history” project to replace a leaking pipe that runs through the Winton Street Overpass. The fact that the project team kept smiling and simply took all of this work in stride speaks volumes about their character and devotion to the residents and businesses of Hayward, that we serve.
The beginning to the project was very unceremonious. Hayward’s 20 inch pipe in the Winton Street/880 overpass had developed a leak and needed to be replaced. The first challenge to overcome was how we would clean the interior of the structure. The space was limited and the debris kept clogging the vacuum truck hose. We finally resigned ourselves to having to go in and clean the interior by hand, with dustpans, foxtail brooms, and five gallon buckets. What compounded the challenge is that we had to make sure that none of the debris rained down on the 880 freeway below.
After getting the okay to proceed with the project from Utilities and Environmental Services Director, Alex Ameri, we started to place the order for the parts in the last few months of 2015. The EBAA Flex-Tends, above, were the longest lead time items. These parts and pipe were hands down the largest that City staff had ever personal worked on.
Day one of the pipe replacement project was ushered in with the arrival of the heavy equipment. Unfortunately, we didn’t get far before encountering the first unexpected revelation. There were large veins of pea gravel near the overpass structure. It started to pour out of the sides of the trench walls and threatened to undermine the very busy West Winton. We immediately had to backfill to prevent that from happening and shifted to Plan B.
Thanks to the expertise of United Trench Safety folks, “Plan B” effectively became driving ¾” steel plates into the ground with the excavator to keep the pea gravel in place thereby preventing the undermining of the very heavily traveled roadway. Staff then welded braces in place and the excavation process promptly resumed.
The next challenge was cutting the asphaltic coated, welded steel and mortar lined 20 inch pipe. Things got smoky and dusty in the overpass and required the use of forced-air respirators. This had to be done because the overpass end walls were formed around the pipe. In order for us to remove the wire sawed concrete plug that surrounded the pipe, we had to cut the pipe in the interior of the overpass. The respirator equipment worked like a charm, as did the 4-1/2 inch mini-grinders equipped with A2Z cut-off wheels!
After a few very clean cuts, we were ready to pull the cut concrete plug ends out of the overpass. And then, out came the reinforced concrete cut sections as well as the first of the old 20 inch pipe. It was exciting to see the old pipe getting pulled out of the overpass. We were not sure how well the 50 year old roller supports would work but they did great, and the Deere 245 pulled the pipe out with ease.
We now had to remove about 35 feet of AC (Asbestos Concrete) pipe so that we could create our new pipe loading pit, and to facilitate the pulling out the old pipe from the overpass structure. While properly shored and totally safe, it was obvious that we wouldn’t be able to work with all of the speed shore braces in the way. So, the folks at Untied Trench Safety, a Hayward business and community partner, delivered a shoring box that would allow us to have the space we needed to remove the old pipe and pull in the new.
We could now start pulling out and cutting longer segments of the old pipe. The many months of planning were starting to pay dividends!
This is a good picture of the freeway below, as seen through the gap. The pencil and glove are included for scale to show both the width of the gap and the roughness of the floor of the overpass. That floor roughness would ultimately prove to be one of the bigger challenges that we had to overcome with this project.
It was time to install the massive TR Flex pulling head on an 18-1/2 foot long stick of pipe and see how some sample insulators would perform as they got dragged over a rough surface. This head is very heavy, the pad-eye on the front of the head is made out of 3-1/2 inch thick steel plate.
This was technically the very first TR Flex joint that the crew had ever assembled. It took about 15 minutes for everyone to wrap their heads around the design and to become complete proficient in the assembly process.
By this time, we had hand cleaned the overpass no fewer than 6 times. Once the pipe was removed, however, there was nothing that would deflect any debris that feel through the seam on the ceiling of the overpass, from traveling through the gap in the floor between the two structures that made up the overpass until the new pipe was in place. We elected to use the Aramark carpet runners to cover the gap. The rental of these made sense because that way we wouldn’t end up buying a 300 foot long carpet runner, and then discarding by sending to a landfill.
It was time to break ground on the east side. The Deere 300 that was going to be used to pull the new pipe in the overpass made short work of the process. We also applied all of the lessons learned from the west side experience, which made this excavation very straight forward. The east side receiving pit was dug in very short order. The shoring box got delivered and dropped into place.
In virtually no time flat, staff was trimming some small protruding pieces of rebar…
…and we added a little temporary base rock backfill to retain the pea gravel until we could get the plates ordered for this side. It was a good thing that staff elected to lay out the rental carpet runners. Once again, the pen and the glove are included for scale. This is debris that could have fallen on the freeway traffic below.
Then, one day, we got word that our prototype pipe sleds were ready, and staff picked them up from RA Metal, in South San Francisco. Staff waisted no time getting the sleds ready for their pull tests. When all was said and done, there was no visible wear to the runners and, while very warm, they could still be touched with a bare hand!
The next step was to deliver the prototype sled and pipe assembly to the overpass to see if it would work as planned there. Staff dragged the lifting chains into place, dropped the spreader beam that was needed to keep the chains away from the gap in the center, and hooked everything up for the test pull. Everything was once again exceeding every ones’ wildest expectations, and the pipe was pulled through the overpass without incident.
The new sleds incorporated some minor design improvements, but substantially mirrored the prototypes’ design. About ten days later the fusion bonded epoxy sleds started to arrive. Staff wasted no time in bolting the sleds onto the pipe for the final test. Our Director requested that the crew perform one final test pull of a three stick pipe train through the overpass to ensure that nothing changed when the pipe was pulled through as a train.
The lead stick of the pipe train was loaded into the loading pit. This pipe would never come out of the overpass again. Despite being pulled all the way through in the form of a three-stick train, that train would be pulled back to the loading pit, and from there the fourth stick, and fifth stick were added.
The three-stick train got loaded, made a full pull without incident to the east, was pulled back to the west end, and then the permanent pipe install started. Everything was going exactly as planned. The months of planning out every detail and revising the plans to accommodate existing conditions were paying off.
We are getting closer to home. We could no longer see the traffic through the gap once the pipe passed the eastern manhole. It was actually an odd feeling for the crew. We had become very accustomed to moving freely through the very dynamic overpass.
And then one day the end was in sight. The last part of the pipe in the overpass was pulled through. The west side (above), the east side (below). The Deere 300 had made the full pull like a champ! The line was actually left pressurized over the 4th of July weekend, and when we returned, the pipe was still holding at 195 psi. The pipe, obviously passed the pressure test with flying colors.
The final tie-in to the existing 30 inch lines were started after staff relieved the pressure in the line and drained the pipe. The original 30 inch AC line was not exceptionally well aligned with the overpass, but that was not going be an issue because of the large gimbled ball ended and telescoping sleeve EBAA Flex Tends that were required by Caltrans on either side of the overpass.
With a final check of the level on the flange of the tee, the east side of the project was tied in. The pipe still needed to be wrapped in plastic to further reduce corrosion, the reinforced concrete plugs in the end of the overpass still needed to be restored, and the trench obviously still had to backfilled, but the piping work on the east side of the project was done!
Staff was justifiably proud of their monumental achievement. Note, that on any given day there were only 3 to 5 people working on this project. The City of Hayward, like most every other utility in the Bay Area, does not have “extra people” available to do this type of work. The same staff still had to repair leaks and breaks in our 350 miles of distribution system, had hydrants to repair and replace, had new water services to install in the numerous developments, installed meters, tested backflow devices, read meters, responded to customer service calls, operated and maintained the tanks, pressure reducing stations, and pump stations of the system, and all of the other responsibilities associated with operating a distribution system in one of the larger cities in the SF Bay Area.
Some might say that we really couldn’t afford to dedicate scarce human resources to a project like this, but in actuality, we can’t afford not to do the this type of work because the problem solving skills and professional development that projects like this offer are absolutely priceless.