DC Water's Rapid Repair of a Waste Water Treatment Plant Piping System

The Blue P lains Advanced W astewater Tre atment P lant owned b y District of Columbia Wa ter a nd Se wer A uthority ( DC Wa ter) is one of the la rgest w astewater treatment plants in the world. O ne particularly critical pipe within the facility is the Nitrification RAS Line, which transports slud ge a nd is loc ated in u nderground galleries. Thr ough inspe ction it w as ide ntified tha t e ight e lbow sec tions of the 84inch ste el pip eline ha d significant thinning and w ere in n eed of repair dur ing the scheduled 2013 pipeline shutdowns. Four 90-degree elbows and four 45-de gree elbows required a struc tural upg rade and CFRP was sel ected as t he appropriate structural l ining s ystem based on DC W ater’s pr evious success ful hi story with t his material. The EPA regulates the amount of time this f acility can be shut down and dictates t hat onl y h alf t he piping can be shut d own at one time, so th e cle aning, inspection, w eld r epairs, CF RP a nd topcoat insta llation, a long w ith f ull c ure of the repair system had to take place over the course of two 5-day shutdown windows. This paper will provide details and owner feedback on the design and construction process undertaken for this unique project.