City of Bend Sewer Structure Improvement

City of Bend Re-Evaluates ConventionalPractices in Sewer Structures
On paper, Bend, Oregon’s $3.8M North AreaSewer Improvements project seems like aroutine, albeit very large effort, to update agingsewer infrastructure. However, a closerlook shows the rebuild and rehabilitationefforts are driving change to some conventionalpractices.

The North Area Sewer Improvements projectincludes the culmination of a five-year effortto resolve a microbial-induced corrosion(MIC) problem caused by hydrogen sulfidegas in the sewer system and especially at themanholes.

Throughout the project, Joe Floyd, owner ofJoe Floyd & Sons, a leading precast concretemanufacturer in the Northwest, took on aprincipal role in finding a practical and highperforming answer to the problem.

He explains, “We were looking for alternativesto new city and county specifications for themanufacture and installation of sewer manholes.The challenge has been to find an effectivesolution that’s affordable, easily installedand locally accessible. That’s where crystallinewaterproofing entered the picture.”

Beyond Conventional Practices
The conventional approach to protectingconcrete sanitary sewer structures againstdeterioration caused by MIC is to use protectivesystems, such as liners and coatings.

The City of Bend and Deschutes County hasbeen using polymer coated manholes for anumber of years. Unfortunately, the manholemanufacturer selected was located severalhundred miles away and the products werevery expensive. Purchase, delivery and installationwere logistically and economicallyprohibitive. Additionally, the engineers hadconcerns about repair and replacement. Forexample, what would happen if the takeoffwas wrong and the manholes were producedincorrectly? What if the manholes needed repair?Would the city have the flexibility towait for a solution?

Like any liner or coating, polymer coatedmanholes require a specialty crew to weld the joints, therefore the civil contractors can’town a job from beginning to end and don’thave control of the schedule.

“The polymer coated manholes are a wonderfulmanhole except for the challenges associatedwith schedule, installation, the potential forinfiltration from the outside to inside, and thatit’s 6x as expensive as a regular concrete manhole,”says Floyd. “We knew that the city wasconcerned with hydrogen sulfide corrosion andhad settled on a solution that, while effective,was very expensive. It was in that search to finda solution that I came across Xypex.”About five years ago, Floyd called on fellowmember of the National Precast Concrete Association,Gainey’s Concrete Products, a producerin Louisiana. He adds, “Their highgroundwater would likely create challengesrelated to hydrogen sulfide corrosion, so Icalled the company representative and he recommendedXypex.”

A high-water table (groundwater) would be aproblem for ‘infiltration’ which can cause linersand coating to lose their adhesion to thesurface. While this is a problem in Louisiana,a bigger issue would be the slow flow of sewageresulting in high hydrogen sulfide gasconcentrations in the pipe and at locations ofhigher turbulence resulting in more microbialinduced corrosion.

For the past 5+ years, Joe Floyd & Sons hasbeen investigating, learning and testing concreteproducts with Xypex crystalline waterproofingsolutions and helping educate cityand county leaders, engineers, specifiers andinspectors.

The Crystalline Edge
Crystalline Waterproofing Technology, used atthe time of batching becomes an integral, permanentpart of the concrete structure. The crystallinechemicals react with the byproducts ofcement hydration to make the concrete waterproofand more resistant to deterioration.When moisture is present, the crystalline structurewill form in the pores, capillary tracts andshrinkage cracks in concrete. Wherever watercan penetrate the concrete, the crystalline formationwill follow. The crystalline formationengages the material filling and plugs the voidsin concrete to become an integral and permanentpart of the structure.

Crystalline waterproofing has all the advantagesof liners and coatings along with considerablelifecycle benefit. The technologyworks within the concrete to make it waterproofand improve durability by filling andplugging pores, capillaries and micro-cracksof the mix with a non-soluble, highly resistantcrystalline formation.

Floyd adds, “I specifically researched Xypexproducts as a potential solution to the hydrogensulfide corrosion problem. From what I’veseen, nobody understands the science of crystallinewaterproofing and no other manufacturerhas the extensive history and testing ofXypex. They have tested and evaluated concretestructures for 50 years in every conceivableharsh environment—I don’t know anyonewho does that.”

Once he’d done his own research on Xypexproducts and capabilities, Floyd contactedSteve Keyser, Xypex’s Oregon representative tolearn more.

“He did a presentation for me and then for thelocal engineers, architects and contractors,”recalls Floyd. “I also shared the lifecycle benefitsof Xypex with my customers and most ofthem were all in. They want the best qualityand longevity.”

However, the presentation had limited value toengineers and architects, who are often restrictedby owner requirements. Floyd continuedto advocate for the benefits.

Two years later, Keyser and Floyd made a followuppresentation on the effectiveness of crystallinetechnology for protection against microbialinduced corrosion caused by acid and sulfateattack focusing on the lifecycle benefits at theCity of Bend engineering offices. This time,twice as many professionals attended and interestwas much greater. Keyser even helped bywriting a specification for Xypex that architects/engineers could simply cut and paste intotheir documents.

Currently, Floyd offers Xypex as an upgrade onmany of his products including septic tanks,cisterns and water troughs. All his experiencesand lessons learned about crystalline waterproofingcame together when the city beganthe North Area Sewer Improvements project.Floyd adds, “The City of Bend was waiting fora good test project to use crystalline waterproofingand evaluate its cost effectiveness.

The North Area Sewer Improvements project,which included the replacement of a numberof manholes, proved the ideal project.”

The Test Bed
The North Area Sewer Improvements projectwill upgrade the city’s sewer pipe and conveyancesystem, which is near capacity. City ofBend consultant, Niall Boggs from Parametrixwrote the test project specifications for Xypexin the manholes.

Floyd explains, “The project went prettysmoothly. We had to do a little education withcontractors about the best mix procedure anddosage rates for Xypex Admix C-500, and jointgrouting with Xypex Patch’n Plug, but weworked through those details with help fromSteve. This was a great project for me as adistributor to see what hurdles we need toovercome and how best to help contractors.”To help inspectors, Floyd’s company colors andstencils manholes to help inspectors identifyXypex-incorporated systems.

“The best part is that the City of Bend hassaved thousands of dollars on every manholeby using crystalline waterproofing instead ofthe polymer coated systems. We’re hoping thatin the future any lift station or any concretestructure to be installed in an area with a potentialMIC issues will incorporate Xypex.”