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KEEPING OCEAN SHORES CLEAN: Coastal Town Relies on Vacuum Sewers

This is an excerpt taken from the article "KEEPING OCEAN SHORES CLEAN: Coastal Town Relies on Vacuum Sewers"  published in Informed Infrastructure, September/October 2016. The entire article can be downloaded from this page.

The city of Ocean Shores, Washington, offers a valuable test case for vacuum sewer reliability and endurance. 

Challenge

The city’s vacuum system is one of the largest in the world, and it’s also mature; most of its components are more than 20 years old and must function in a challenging operational environment. What makes Ocean Shores even more valuable as a sewer system comparison study is that it also has gravity sewer and grinder pump systems to maintain. Like many seaside communities, Ocean Shores began as a collection of mostly vacation homes and campsites. Located about 50 miles west of Olympia, Wash., the small community incorporated in 1970 with a population of about 900. At the time, lot sizes averaged about 7,600 square feet and nearly all had septic sewer systems to handle wastewater.


Its location on the Pacific Ocean encouraged growth and tourism. Up to 8,000 people were in Ocean Shores on summer weekends by the mid 1970's. Predictably, the high concentration of septic tanks and limited wastewater treatment led to a eutrophication problem that showed up as algae bloomed in the area’s many canals and ponds.


In 1980, a consultant recommended gravity sewers be installed throughout the town, but residents were cool to the idea due to the staggering cost estimate: $80-$90 million.


“That was quite a chunk of change,” notes Miles Beach, who recently retired as the city’s waterworks superintendent. “A lot of that cost was to excavate and then repave the streets for collection lines, and install more than 50 lift and pump stations.”

Solution



That solution proved too expensive for Ocean Shores. The septic tank problem sat on the back burner until the 1990s, when the state of Washington implemented a new environmental policy stating that house lots had to be a minimum of 15,000 square feet to accommodate a septic sewer system. This resulted in a construction moratorium in Ocean Shores and stagnant economic development.


“That led us to look at alternative sewer systems,” adds Beach. “It turned out that vacuum sewers were the lowest cost. Our public works director at that time got in touch with Airvac. After some research, we decided to do a test project. We worked with their engineers and came up with a design estimated to cost $4.5 million for about 2,400 connections. It actually cost less—about $3.8 million.”


That initial test project was completed in 1995 with minimal disruption to the community. The city imposed a tight timeline of two years to complete its new vacuum sewer system, but the project took only 18 months with five different contractors collaborating on the effort.


Marshall Read has operated the city’s vacuum sewer for  more  than 20 years—he and a crew of three inspect the system daily. They’re intimately familiar with every detail of the Airvac system and have two decades of data to back them up.


“In flatland conditions like we have, with a high groundwater table, vacuum sewers are by far the best alternative of all sewer systems,” says Read. “Maintenance on vacuum sewers is very easy, even after 20 years.”


“Compared to grinder pumps and STEP (septic tank effluent pumping) systems, I’d choose vacuum sewers every time,” confirms Read. “In my mind, it’s the way to go with regard to operational integrity. It’s the least prone to trouble, and, if you do have trouble, you are not wading in sewage.”


“I would invite people to look at Ocean Shores’ sewers today after nearly 25 years and see how low the O&M costs are,” adds Beach, who spent 36 years in public works before retiring in 2013. “I’ve never been more pleased with a system in all my life.”

Key Features


The current Airvac system in Ocean Shores was designed to serve 11,520 lots. Service currently is provided to more than 10,000 lots, some permanently occupied and some not.  There are approximately 4,800 active vacuum valve pits, 96 miles of vacuum mains and seven vacuum stations. A $12 million treatment plant built in 2000 serves the city and some of the surrounding communities in Grays Harbor County.

Daily sewer maintenance includes stops at the seven vacuum stations. The duties are divided among the three members of Read’s team.

“We do a daily inspection at each station, which takes about 30 to 45 minutes,” notes Read. “We do a little cleaning, and we check the systems. We typically change the oil in the vacuum and sewer pumps once or twice a year. The oil that comes out of them looks new. These pumps are all 17 years old or more, with about 9,000 hours of operation each.”

There are about 4,800 active valves in the Ocean Shores vacuum sewer system. It’s estimated that the combined active valves in the system cycle or “fire” approximately 4.8 million times per month. Because of the area’s high water table and sandy soil, many of these valves and controllers are in standing water for six to eight months a year. Yet the durability of the devices is remarkable, according to Read.

“In the course of a year, we probably replace less than a dozen valves,” explains Read. “Typically it is because an internal breather popped out and is allowing sewage to get around the valve. We’ll replace that valve with a working valve, and take the one that was removed back to the shop for a good cleaning and testing. We keep it and reuse it when another valve needs to be cleaned and tested. We keep very few replacement parts in stock. In 20 years, we’ve probably purchased less than $3,000 in component parts,” he adds. “Most of the controllers and valves have been in daily use since 1996 and never needed repair.”

Technical Data

Age of system: 20 years
Number of parcels (total): 11,520
Number of parcels with a house: 10,000
Number of active vacuum valves: 4,800
Number of vacuum valves replaced/year: < 12
Number of valve cycles/month (estimated): 4.8 million
Number of callouts/month (wet season): 5-6
Number of callouts/month (dry season): 2-3
Average time to respond and correct problem: 90 minutes

Locations and Contact

North America

Aqseptence Group, Inc., Rochester, IN

Sales and Manufacturing Location
4217 N Old U.S. 31,
Rochester, IN 46975
USA

Tel: +1 574 223 3980

Fax: +1 574 231 7424

info.airvac@aqseptence.com

North America

Aqseptence Group, Inc., Tampa, FL

Sales Location
3180 Curlew Rd., Suite 207
Oldsmar, FL 34677

USA

Tel: +1 813 855 6297

Fax: +1 813 855 9093

info.airvac@aqseptence.com

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