Feb. 16, 2004 -- Situated in the heart of the Tualatin Valley, midway between majestic Mt. Hood and the spectacular Oregon coast, Beaverton is a city that devotes 1,000 acres to 100 parks so one is within a half mile of every home.
With this emphasis on green space, Clean Water Services, the regional wastewater and stormwater utility, set the highest priority on reliability in planning a sewer upgrade through Tualatin Hills Park and Recreation District's 219-acre Nature Park.
Following the Beaverton Creek stream corridor, the new sewer line would replace the old one that was too deteriorated to repair. According to Steve Lampert, one of Clean Water Services' project managers, "The main consideration was we didn't want to have to go back out to the wetlands to make repairs."
A corrosion resistant product that would remain leak-free for years to come was exactly what they were looking for.
The specifications included 8,000 feet of pipe - 2,100 feet of 48-inch, 3,700 feet of 60-inch and 2,200 feet of 66-inch. The alternatives were profile wall polyethylene and centrifugally cast, fiberglass-reinforced, polymer mortar (HOBAS CCFRPM) pipe. Neither of these is affected by hydrogen sulfide as unlined concrete pipe would be.
High Stiffness Design
The contractor, John L. Jersey & Son, Inc. of Portland, Ore., bid the job with HOBAS CCFRPM pipes. John F. Kalkhoven, P.E., Jersey project manager, said that strength and durability were two of the important reasons his firm chose HOBAS.
He explained that the profile wall polyethylene was not as stiff as the HOBAS product and it would require additional care to insure a quality installation. He explained, "The polyethylene pipe would have required a filter cloth liner for the excavation and complete coverage with bedding rock." The HOBAS trench details did not require filter fabric and needed bedding only up to the springline.
"Jersey & Son told Clean Water Services' staff during an interview that HOBAS pipe would cost less than the profile wall option to install and would make installation easier," Lampert added, "The biggest benefit of HOBAS pipe is constructability. It is strong and provides ease of construction."
All Fiberglass System
In order to accommodate the many changes on the sewer line as it followed the meandering creek, Jersey installed manholes. It wasn't uncommon to have a series of manhole runs of only 100 feet, 70 feet, 130 feet then 500 feet. "The custom-made manholes simplified this task," Kalkhoven said. HOBAS manufactured each manhole with the correct miter and FWC couplings so that they were easily joined.
"For the first 2,000 feet of pipe, we were limited to an easement 30 feet wide," explained Kalkhoven. "Since the excavation for the 66-inch pipe was eight feet wide, we had an 11-foot path to bring everything in. All the pipe and bedding had to come from behind but this was no problem. We'd lay the pipe, then install the tee-base manhole and proceed to the next joint. After the manhole bases were installed, we put the risers in place and added the cover. The risers were delivered complete including fiberglass ladders."
The 48-inch diameter manhole risers were reduced to a standard 24-inch top. HOBAS also made the manhole covers, which were attached with a gasket and bolts ensuring they would be watertight as the summer water levels rise. "HOBAS supplied a complete package," Lampert continued. By providing the pipe, manhole tee bases, risers and lids, HOBAS makes jobs convenient for the contractor.
Total Installed Cost
Lampert said that despite the actual cost of HOBAS pipes being higher, it was the less expensive option on a total installed cost basis. According to Jersey & Son, the cost of the cloth liner, extra bedding and additional labor for a more difficult installation clinched the decision. "The numbers stood on their own based on my view," said Lampert. "Also, it would provide an end product that Clean Water Services could be comfortable with."
Look to the Future
Both Lampert and Kalkhoven visited the HOBAS plant and were impressed by the quality process, so, even though they had never used it before, Jersey based their bid on HOBAS pipe.
"The quality control is just phenomenal," Lampert exclaimed, "The computer controlled systems and state-of-the-art manufacturing process assures that the pipe is of consistent high quality."
"It is a good application," Lampert said, "and I think that more municipalities and districts that do this sort of work are going to be looking at this kind of a design situation. HOBAS pipe really excels in large diameters and is a good option when future repairs would be difficult to make.
"We want something that will be watertight," Lampert added. "This installation will probably last 100 years. It will outlive me - I know that. I don't expect to have to go back in there and fix anything for a long, long time."
HOBAS pipe is manufactured in sizes from 18 inches to 110 inches in pressure and non-pressure classes. For more information, please contact HOBAS at 800-856-7473, 281-821-2200 or e-mail at firstname.lastname@example.org. Facts are also available at www.hobaspipe.com.