ATFP Culvert Grates

Ferguson Trenching was provided a contract to mitigate security deficiencies within the existing storm drain infrastructure for NSA Bethesda.  NSA Bethesda is responsible for base operational support for its primary tenant, the Walter Reed National Medical Center.  The existing security grating on several storm drain pipes and culverts had deteriorated beyond function or repair. FTC was contracted to demo and remove the existing culvert grates and to fabricate and install new security grating at locations near Gates 3, 4, 5 and Perimeter Road.

The Gate 3 location required the use of a 55-ton crane w/ a 115’ reach to remove the existing grates and to lift the 8’ x8’ square grate, 70” round grate and (2) 24” round replacement grates over tree’s and into the stream bed for install onto the culvert.

Crews also had to Install Class 2 Rip Rap at the remote outfall location near Gate 5, traversing an environmental Forestation area. They also had to repair a 42-inch concrete Flared end section that separated at the joint from the mating storm drain pipe.

The Perimeter Road location provided its own unique challenges as the culvert locations were located in the bottom of a ravine, home to Rock Creek which is appropriately named. Rock Creek turns into a river with any significant rainfall as all the drainage from the Bethesda campus and nearby golf course funnels into this area. We again had to Demo, remove, fabricate install new security grating. On the north end of the culvert, we installed a security grate which was 12’x 6’ and weighed 1,450 lbs. On the south end of the culvert, we were required to install a 10’x 7’ trash rack with maintenance access gate that weighed 1,270 lbs. as well as install (5) 30” round concrete reinforced galvanized steel bollards. Each bollard was 11’ overall in length and was to be embedded into the creek bed 6’ deep. Once excavated and the reinforcing steel was installed, we then had to pump concrete from the road down to the creek bed to pour the bollards. This work required us to install a dual pipe flume system and multiple pumps to bypass the creek.  A 9,000 lb excavator with a rock breaker and bucket was needed to remove rocks and excavate and had to be lowered into the steam bed via a 100 Ton Crane.  Due to the size of the crane we had to request a road closure and detour from NAVFAC which had a 30 day approval process so staying on schedule was imperative as the road closure couldn’t easily be rescheduled. As Perimeter Rd is the main route for delivery trucks for Walter Reed much of the work needed to be performed on multiple weekends as the road closure wasn’t permitted during weekdays.

Project Manager Jerry Nicholson and the crews of James Cook (William Green, Steve Blake, Vance Shubert) and Denny Shaw (Silverio Arreguin, Joseph Cumberland) as well as Joe Thomas are to be commended for their extra efforts and for completing the project on schedule and well below budget.