Trenchless Technology

NOV 2018

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Page 32 of 68

32 T R E N C H L E S S T EC H N O LO GY N OV E M B E R 2018 DISTRICT OF COLUMBIA WA S H I N G TO N Oregon Avenue NW Sewer RehabilitaĈŸon Bradshaw Construction Corp. Bradshaw is in the close-out stages of a 4,300-ft long , 24-in. sewer inter- ceptor project for DC Water in a tight corridor of Washington, D.C ., between Rock Creek Park, owned by the Na- tional Park Service, and the residential neighborhoods of Chevy Chase and Barnaby Woods. The project included 2,600 ft of tunnels installed in three drives at depths of up to 90 ft . The 60-in. tunnels, beneath Oregon Av- enue and Bingham Drive, are accessed from six shafts up to 48 ft deep. Sub - surface conditions consist of Tonalite rock ranging from slightly weathered to highly decomposed. Of the total tunnel footage installed, 2,150 ft of 60-in. steel casing was installed in two microtunnel drives, the longest being 1,866 ft in a single push. The third mi- crotunnel drive on the project was a 625-ft radius 450-ft S -curve installed using 48-in. RCP. Access for the tunneling operations was especially challenging on the proj- ect . Avoiding existing utilities, main- taining local traffic for residents and emergency services, and confining the installation to the restricted rights-of- way provided led to both Bradshaw 's longest microtunneling drive and its first curved drive. The project also included 1,700 ft of open-cut sewer, three connections to the existing sew- er system and the abandonment of the existing 15-in. sewer being replaced. The $16.82 million project began in December 2016 was 99 percent com- plete as of November 2018. Engineer: Johnson, Mirmiran, & Thompson; Equipment : Herrenknecht AVN-1200 MTBM (60-in.). Bradshaw Project Manager: Todd Brown. FLORIDA R U S K I N South County RePump Station Water TM to 19th Ave. CIP 31969 Bradshaw Construction Corp. This $2.117 project consists of 1,055 lf of 48-in. steel casing for 16- in. DIP carrier pipe with 16-ft by 30- ft launch shaft and 12-ft by 16-ft re- ceiving shaft for a new water main to accommodate expanding population . Shaft depths were approximately 25 ft and below the water table. Ground conditions were mostly sand. Bradshaw double- shifted the min- ing operations to help cope with a tight schedule. Crews also had to deal with overhead power lines. The proj- ect began in June 2018 and is expect- ed to be complete before December. Owner: Hillsborough County Pub - lic Water Utilities Department Water Resource Division; Contractor: Westra Construction Corporation; Engineer: Black & Veatch; Equipment : Herren- knecht AVN-800A . Bradshaw Project Manager: Mike Wanhatalo. GEORGIA PA N T H E R S V I L L E Dekalb County 30-in. Watermain Re- placement at I-285 & Panthersville Rd. Bradshaw Construction Corp. Bradshaw recently completed con- struction on a $1.246 million micro - tunneling project , installing 245 ft of 60-in. steel casing under I-285 for a 30-in. DIP water transmission main. The tunnel was installed behind a Herrenknecht AVN-1200 microtunnel boring machine. The job included 32- and 16-ft di- ameter liner plate launch and recovery shafts, with sample borings showing loose sands and the water table settling near tunnel casing crown. Substantial rock (gneiss) was encountered on the launch shaft, requiring unanticipated blasting to reach final grade. Partner- ing with John D. Stephens, Bradshaw was able to quickly adjust course to perform the blasting , keeping the proj- ect on schedule. Once the shafts were down, the tunnel was successfully in- stalled through the mixed face/mixed reach conditions, with no settlement or grade disruptions despite transi- tioning from gneiss to sandy clay mid- way through the drive. The project took place from August to December 2017. Owner: Georgia Department of Transportation; Contractor: John D. Stephens Inc. (Prime: Pittman Con- N O R T H A M E R I C A N M I C R O T U N N E L I N G 2 0 1 8 R E V I E W M I C R O T U N N E L I N G J O B L O G 2 0 1 8 Oregon Avenue NW Sewer Rehabilitation

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