June 2014, Issue 71

Contents1 I Hydroelectric Power Plant Upgrades Penstock4 I Going Under the Oklahoma River6 I Large Diameter Slipline Completed in Milwaukee

Hydroelectric Power Plant Upgrades Penstock

PipeLine

Continued on page 2

New Milford, Conn., is home to the Rocky River Hydroelectric Power Plant, the first large-scale pumped-storage development in the United States. The American Society of Mechanical Engineers declared it a National Historic Mechanical Engineering Landmark.

The original wooden and steel penstock transported water back and forth between Candlewood Lake and the plant’s surge tank above the Housatonic River by means of the Rocky River Hydroelectric Power Plant. The station’s upper reservoir, Candlewood Lake, was named for nearby Candlewood Mountain and is the largest man-made lake in the state.

An eight-square-mile storage area is filled by pumping water from the Housatonic at periods when electricity to run the pumps is least expensive.

When demand reaches a peak, water is released through the same penstock, and the motors driving the pumps reverse to become generators to produce electricity. Power generated by releasing the same water can then be sold at higher rates during periods of peak demand.

RigHTThe 15-foot diameter woodstave penstock was replaced with 10-foot diameter fiberglass pipe.

BELOW The existing wood penstock had outlived its useful life.

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Continued from page 1

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“The statement that a hydro-electric plant can pump its own water supply sounds absurd on the face of it, yet this is virtually what happens in the case of the Rocky River Hydro Plant ...,” said chief engineer Paul Heslop, at a Connecticut Society of Civil Engineering meeting in 1928.

This 47 year old penstock was made of Douglas fir that was held in place by iron rings. it was originally built in 1928 and replaced in 1965. As it aged, it began to sag and leak into the drainage ditches that run parallel to the pipeline.

“The wood penstock had clearly outlived its useful life,” said Richard Laudenat, CT Hydro plant manager for FirstLight Power Resources, the owner and operator of the Rocky River Hydroelectric Power Plant. “To limit the amount of water leakage and extend its useful life, a second set of bands was installed around its circumference and joints around the pipe

were also fitted with wedges. Both of these maintenance activities were to no avail

as the wooodstave pipe aged and the sagging continued, which opened it to increased leakage.”

Kleinschmidt Associates, specializing in hydro-generation and water resource projects, was hired to design a replacement pipeline.

Reliable Replacement

The replacement penstock was designed to be a reliable, cost effective

design and as much as possible, maintenance free. Most of the replacement

penstock was half-buried to the center line, except for two twenty-foot sections at the

upper end of the penstock. This 40-foot section supported on concrete cradles allows for surface water drainage from a hill above the penstock. Steel transition sections at the upper and lower end of the new penstock allow for the new 10-foot fiberglass pipe to connect into the existing 15-foot steel sections.

This three million dollar project went out to bid in January 2012 and was completed in December 2012. The 15-foot diameter wooodstave

BELOWSteel transition sections at the upper and lower end of the new penstock allow the new 10-foot fiberglass pipe to connect to the existing 15-foot steel sections.

The section supported on concrete cradles allows for surface water drainage from a hill above the penstock.

HOBAS Pipe USA supplied 950 linear feet of 120-inch centrifugally cast,

fiberglass reinforced, polymer mortar (CCFRPM) pipe.

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penstock was replaced with 10-foot diameter fiberglass pipe. HOBAS Pipe USA supplied approximately 950 linear feet of 120-inch piping that included three miter joints of centrifugally cast, fiberglass reinforced, polymer mortar (CCFRPM) pipe. it was manufactured with a stiffness class of 36 psi and pressure class of 26 psi. The line operates under a nominal pressure of 22 pounds per square inch.

Kleinschmidt evaluated three pipe materials for this project: plastic, steel and fiberglass. HOBAS was the lowest cost supplier and after review by the owner was awarded the contract. Even as the lowest cost option, HOBAS technically exceeded the other materials in design and installation. it allowed for easy connection into the steel transition pieces and is UV resistant. in addition, the hydraulic capacities create more flow going into the turbine; therefore more electricity is generated due to reduced head losses. As compared with other piping materials, the HOBAS CCFRPM pipe exhibits a lower friction factor, and for pipes of the same diameter, this will mean less head loss in the penstock piping.

The FWC coupling joint utilized on this project is a pressure joint. it is commonly used in direct bury applications and also for above ground installations such as penstocks. it is a structural filament wound sleeve overwrapped and mechanically locked to an internal full-faced elastomeric membrane. The sealing design includes both lip and compression elements so the joint is suitable for both non-pressure and pressure service. HOBAS supplied the FWC couplings with a UV coating that will protect the joints from long-term sun exposure.

Quick Installation

The installation contractor, Blakeslee Arpaia Chapman (BAC), took 11 days to remove the existing wooodstave penstock. “We cut the existing penstock into 20 foot sections and as these sections were removed we dropped them onto timbers causing them to implode,” explained Joseph DelVecchio, construction superintendent, BAC.

BAC then efficiently installed the new penstock. “Our best production rate was 14 joints in one day. The pipe joined easily and when honing the pipe we used less tonnage than was specified for a pipe of that size,” explained DelVecchio. BAC evaluated two alternative orientations of the replacement penstock and decided to utilize mitered joints to accommodate the change in the pipe direction.

HOBAS provided fittings manufactured of the same materials as the pipe, three mitered elbows of nine, 18 and 20 degrees. Because it was a pressure application, BAC decided to encase the elbows in concrete to resist deformation.

Product Confidence

With the line installed, the contractor performed visual inspection and testing of the joints. “We felt confident in the material since we have used it previously on other projects, particularly the Jackman Penstock, and are familiar with its performance. The FWC coupling proved to be an effective and reliable method to join the sections of HOBAS pipe and everyone was very pleased that no leaks were identified and no joint repairs were required,” explained Harold Thompson, senior consulting engineer, Kleinschmidt.

“The new penstock continues to meet all of our expectations after its first winter under severe New England weather conditions,” stated Laudenat. “The hydraulic performance of the very smooth interior of the fiberglass pipe allowed for a reduction in the diameter of the pipe. This smaller size reduced the installation project’s capital costs and made shipping by truck a much more viable alternative.”

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Year of construction 2012 Total length of pipe950 feetDiameter120-inchStiffness class36 psiinstallation methodAbove GroundApplicationHydro PenstockClientFirstLight Power ResourcesinstallerBlakeslee Arpaia Chapman AdvantagesQuick Installation, Leak-free Joints

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Oklahoma City is the most highly populated city in the state and the 29th largest city in the U.S. At 621.2 square miles, it is one of the five largest cities in the country in geographic area. The city spreads into four counties: Oklahoma, Canadian, Cleveland and Pottawatomie. Consisting of over 1.2 million people, this region is Oklahoma’s largest metropolitan area.

For many Oklahoma City residents, the waterway now known as the Oklahoma River was long thought of as little more than a drainage ditch. But all that was changed by the Metropolitan Area Projects (MAPS), a bundle of nine major Oklahoma City projects to be funded by a five year sales tax increase. in December of 1993, MAPS was enacted as it squeaked by voters.

Under the provision of MAPS, a seven-mile stretch of the North Canadian River that flows just south of downtown was transformed as part of the original initiatives. The $54 million development included dams to raise the water levels, recreational trails and more. These dams created river lakes for recreational activities. This seven-mile stretch was renamed “The Oklahoma River” in 2004.

Oklahoma City has completed the $6 million Oklahoma River inverted Siphon System

improvements, Phase ii project. This project included the potential rehabilitation of an existing three-barrel inverted siphon, new inverted siphon, a sewer flow distribution vault and a sewer line connecting the new inverted siphon to the collection system. This project increased the city’s capacity to transport sewage from south Oklahoma City to the North Canadian Wastewater Treatment Plant. The existing siphon had inadequate capacity to handle flows during wet weather events. The project was developed to help reduce sanitary sewer overflows in the Brock Creek and Lightning Creek sewer sheds.

Field Versatility

The new inverted siphon was installed under the Oklahoma River with 587 feet each of 24- and 48-inch fiberglass pipe. inverted siphons allow storm water or wastewater sewers to pass under obstructions such as rivers.

in addition, 2,500 feet of 72-inch sanitary sewer main was installed by direct bury. HOBAS Pipe USA was the pipe supplier for Phase ii and custom manufactured centrifugally cast, fiberglass reinforced, polymer mortar (CCFRPM) pipe for this project.

instead of continuing with the 72-inch pipe into

Going Under the Oklahoma River

LEFTAccess to the river with equipment and materials proved difficult, working with Oklahoma DOT a solution was developed.

ABOVE The siphon was installed under the Oklahoma River.

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the siphon, the dual line was preferred. “The smaller pipes generate flow velocities high enough to scour sludge buildup. The 72-inch pipe velocities are fine for the normal grades, but at the siphon the velocities would drop, causing solids to drop out and block the flow,” explained E. O’Neil Robinson, P.E., associate, Cardinal Engineering.

Ease of Installation

The schedule for the siphon installation was time-sensitive due to the activity on the Oklahoma River. This particular section of the Oklahoma River is the site of the Oklahoma City Boathouse District which includes rowing clubs. “We only had about 60 days to construct the new siphons. Since we had to lower the water level for construction, we had an agreement with the City that the water level would be raised to the appropriate level for the planned rowing events,” stated Robinson. it was built into the contract that the installation contractor would receive a bonus of $100,000 for completing this section by the requested due date. Lewis Contractors of georgetown, Texas, was the installation contractor for this project and received the bonus for completing the project by the due date. Despite a four week rain delay, Lewis finished the project on time. With the water level lowered by the dams and controlled by a dewatering process, the siphons were installed.

Soil conditions presented a problem. “The biggest challenge of the siphon installation was the depth. in some areas we were 30 feet deep to rock; soil conditions were sand and water. it was a challenge to shore the area and keep the trench dry,” said Bill geiser, north Texas area manager, Lewis Contractors, inc. As the pipe was laid and joints connected, it was encased in reinforced concrete and covered with 18-inch rip-rap. The pipe was encased in concrete to prevent floatation. Also, this section of the river is periodically dredged, so the concrete would act as a barrier in case contact was made with the dredging equipment.

Forty-five degree elbows were manufactured of the same material as the CCFRPM pipe. They were designed to take the flow from the 72-

inch line into the smaller siphons and feed it into the 72-inch line on the other side of the river via inlet and outlet structures.

Construction Benefits

“We choose to specify CCFRPM in the design because we felt very comfortable using the product and it was appropriate for this project due to the construction technique chosen and the time constraints imposed,” said Robinson. The pipes light weight led to a faster installation due to the ease of handling using lighter equipment.

“Access to the north side of the river with equipment and materials was difficult as it is confined by two major highways, interstate 35 and interstate 40. We worked with the Oklahoma Department of Transportation (ODOT) to develop a plan,” explained Robinson. Temporary access was proposed to coordinate entry and exit from interstate 40 right-of-way with ODOT.

in addition to the added capacity, the new siphon allows for easier and safer maintenance of either the existing or new siphon. The existing siphon, constructed of 24-, 30-, and 42-inch pipe, was cleaned and inspected to determine if it needed to be rehabilitated.

The 72-inch direct bury portion was 25 to 30 feet deep. “Coarse sand and ground water were about ten feet above the pipe. We had to encase the CCFRPM pipe in flow fill to prevent floatation,” stated geiser. The project was completed and is in service.

Year of construction 2013Total length of pipe3,674 feetDiameter24-, 48- and 72-inchStiffness class72 psiinstallation methodDirect BuryApplicationSanitary SewerClientCity of Oklahoma CityinstallerLewis Contractors, Inc.AdvantagesLight Weight, Fittings

BELOW RigHTThe new siphon consisted of 24- and 48-inch HOBAS fiberglass pipe.

BOTTOMSeveral fittings were provided for this project, they were manufactured with the same materials as CCFRPM pipe.

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Year of construction 2012 to 2013Total length of pipe4,500 feetDiameter126-inchStiffness class46 psiinstallation methodSliplining

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Milwaukee, the largest city in Wisconsin, has a population of approximately 600,000. The city lies along the shores of Lake Michigan, one of the five great Lakes of North America and the only one located entirely within the United States. One third of Milwaukee’s sewer system is served by combined sewers that carry both wastewater and storm water. During heavy rain, the flow in combined sewers can reach capacity due to the inflow of rainwater that runs off of the streets as well as infiltration from leaking infrastructure.

Milwaukee, like many cities, is working to upgrade and separate their complex sewer system. As part of the upgrade, a 4,500-foot section of an existing combined sewer was identified as needing rehabilitation.

“The combined sewer was constructed in 1925 and varies in depth from 63 feet to 103 feet within the project limits,” explained Timothy Thur, chief sewer design manager, City of Milwaukee. “The sewer was showing structural distress, developing cracks throughout. There were multiple leaks through the cracks and significant ground water infiltration. Large mineral deposits were also present at various locations in the sewer.”

After rehabilitation, this line still operates as a combined sewer. The City of Milwaukee looks for strategic opportunities to separate the combined sewer system, especially when they are near a river. “in addition, we look for opportunities to install green infrastructure as part of paving and public works projects,” continued Thur. The existing 144-inch monolithic concrete sewer needed repair in order to restore both hydraulic capacity and structural integrity and to eliminate infiltration. it was sliplined with 126-inch centrifugally cast, fiberglass reinforced, polymer mortar (CCFRPM) pipe manufactured by HOBAS Pipe USA. This is the first project in which HOBAS Pipe USA custom manufactured pipe of this diameter and it was the largest fiberglass sliplining job done in North America up to that time.

“We see a trend in the sewer market toward larger diameters and we are investing in our facility to ensure we meet the needs of our customers.

Recent investments in our manufacturing plant and test facilities allow for future diameter growth,” said Kimberly Paggioli, P.E., vice president, marketing and quality control, HOBAS Pipe USA.

Restoring Hydraulic and Structural Integrity

“When the project was being designed, we looked at both cured-in-place and sliplining for rehabilitating the existing sewer,” Thur said. “Due to the depth and amount of flow in the sewer, we chose to bid the project specifying sliplining using 126-inch diameter fiberglass mortar pipe. The successful contractor, Michels Corporation, selected HOBAS as the supplier for the pipe.”

Sliplining is one of the oldest and most reliable methods for trenchless rehabilitation of existing pipelines. This installation method is used to repair leaks, restore structural stability and increase hydraulic efficiency to an existing pipeline. it may be performed by slipping a pipe into the existing host from an access shaft, or can be completed by installing a smaller “carrier pipe” into a larger “host pipe” placing one at a time. Typically, the annular space between the two pipes is grouted and each manhole-to-manhole run is sealed. Sliplining allows for a limited surface footprint which is especially important in populated areas since it minimizes disruption of businesses, highways, railways, etc.

On the North 26th Street project from West St. Paul to West McKinley Boulevard., the existing line was 144-inches in diameter and it was sliplined with nominal 126-inch diameter CCFRPM pipe. With an outside diameter of 132 inches, the clearance was only six inches radially at the pipe barrel. An important consideration in sliplining is the hydraulic requirements of the project. The capacity of a pipeline is modified due to sliplining and the effect will be dependent on the relative sizes

Large Diameter Slipline Completed in Milwaukee

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Year of construction 2012 to 2013Total length of pipe4,500 feetDiameter126-inchStiffness class46 psiinstallation methodSliplining

ApplicationSanitary SewerClientCity of MilwaukeeinstallerMichels TunnelingAdvantagesStructural Integrity, Increased Capacity

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of pipes and their respective hydraulic characteristics. Even though there was a reduction in diameter, the capacity of the line was not only maintained, but increased.

A tool for evaluating a rehabilitated pipeline can be found

at http://hobaspipe.com/7159/. The tool assumes that two pipes

of different diameters are installed on the same grade in a gravity flow

situation, which would be the case in most sliplining instances.

To meet the structural requirements, the liner pipe was designed with a stiffness class of 46 psi and manufactured with low profile bell joints. The low profile bell-spigot joint consists of an integral straight bell fixed to one pipe end that seals to the spigot end of another pipe by compressing an elastomeric gasket contained in a groove on the spigot. This joint is intended for sliplining applications for non-pressure service and provides leak-free capability.

“The ASTM standards require the pipe manufacturer to run the product line through a variety of factory tests including, in this case, ASTM D4161, Standard Specification for Fiberglass Pipe Joints,” explained Truong Do, process quality control, HOBAS Pipe USA.

“HOBAS performed this test on low profile bell pipe joints of this

configuration at a test pressure of 50 psi, well above the

anticipated operating pressure of the gravity pipeline.”

Ease of Installation

Michels Tunneling of Brownsville, Wis. was the installation contractor for this project. A leader in the tunneling industry, Michels has installed CCFRPM on previous projects. “in addition to pricing, Michels selected to install HOBAS because of an excellent past working relationship,” stated Russ Pollard, project manager, Michels Corporation.

The field service department from HOBAS was on-site during installation. “The specification required our input on their plans regarding grouting and floatation restraint systems (blocking), along with their general installation plans,” stated Randy Whiddon, field service manager, HOBAS Pipe USA. “We are, however, happy to provide input regardless of spec requirements. HOBAS supported Michels with numerous communications regarding installation, grouting, and blocking and provided on-site support via a HOBAS Field Service Technician visit. Open communication is very important for the success of critical projects such as this one. While on site, the HOBAS Field Service Technician greeted the Milwaukee Mayor Tom Barrett, who was visiting Continued on page 8

LEFT (FROM TOP DOWN)The 126-inch pipe joints were factory tested to verify the leak-free capability of the low profile bell joint supplied.

Joe Moles, pipe production manager, HOBAS Pipe USA and Juan Gutierrez, senior production manager, HOBAS Pipe USA inspected the first pipe manufactured for the large diameter slipline project.

4,600 feet of 126-inch pipe was shipped over the course of eight months.

The 126-inch CCFRPM pipe was sliplined into an existing 144-inch monolithic concrete sewer.

The Hydraulic Calculator can be found at http://hobaspipe.com/7159/

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PRESORTEDSTANDARD

U.S. POSTAGE PAIDN. HOUSTON, TX

PERMIT #280

Hobas Pipe USA1413 E. Richey RoadHouston, Texas 77073Tel: (281) 821-2200

ADDRESS SERVICE REQUESTED

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Continued from page 7

the jobsite on the same day, which highlights the high-profile nature of the job.”

The pipe was carried in on rails one length at a time. “it was a live tunnel, the water was only about six to 12 inches deep,” stated Pollard. Michels used a tugger to pull the pipe through the tunnel and a skid steer to follow and assist in pushing, setting in place and final blocking. The pipe was installed in only four runs through two drop shafts and three manholes. The runs were 1,372 feet, 1,638 feet, 1,300 feet and 267 feet.

“Due to the size of the pipe, it was little more cumbersome than smaller diameter pipe, but once we developed a safe procedure and system of

installation, the install went smoothly,” explained Pollard.

With the pipe installed, grouting was the next step. The line was grouted in three stages filling the annular space between the existing pipe and the new fiberglass pipe. Proper grouting of the annular space safeguards a long life for the pipeline as well as minimizing the possibility of subsidence as the original host pipe further deteriorates.

There was a final visual survey done at the completion of each section to verify the installation. With the line in regular service, Thur concluded, “We are very satisfied with both the product used for the lining and with the way the project was done.”

ABOVEHOBAS pipe was lowered into a pit during the sliplining rehabilitation of a failing sewer built in 1925.

Once the pipe was lowered into the pit it was then carried in one at a time on rails into the live tunnel.

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