Construction of Bogota-Fucha-Tunjuelo Wastewater Interceptor Starts in ColombiaThe Bogota water and wastewater agency (EAAB) is responsible for the construction of a wastewater interceptor to prevent sewage discharges into the Bogota, Fucha and Tunjuelo rivers in the southwest of Bogota and, in this manner, improve the living conditions of more than three million residents in Fontibon, Kennedy, Puente Aranda and Bosa. The interceptor will run parallel to the Cundinamarca canal and the Bogota river, from the mouth of the Fucha river with its confluence with the Bogota river in Fontibon to the confluence of the Tunjuelo river with the Bogota river in Bosa. It is 9.4 km long and 3,750 mm in diameter, at a depth of 15 metres below the surface. The project also includes a 45 m x 6 m slurry wall shaft and open trenching to lay a pipe. The project will cost COP157 billion in designs and construction. To build it, the EAAB hired the consortium Interceptor Fucha-Tunjuelo (IFT) formed by CSM Bessac (France), Soletanche Bachy Cimas (France-Colombia) and Conconcreto (Colombia). CSM Bessac is in charge of the construction. The firm brought in its expertise in selecting the machine and ancillary equipment for the project. CSM Bessac's staff includes a technical manager, a tunnel chief engineer, a lead mechanic and three operators. Visit www.csmbessac.com, www.soletanche-bachy.com, www.conconcreto.com and www.acueducto.com.co Project benefitsThe fundamental objective of the scheme is to collect the wastewater to prevent direct sewage spills into the Fucha, Tunjuelo and Bogota rivers and to link with the treatment works. The tunnel, which will hold 21 cubic metres of sewage per second, will reorganise all the drainage system in the Fucha, Tintal, Fontibon and Zona Franca basin. Not only will the project improve the life of the residents in the southwest of Bogota by eliminating plagues like insects and rodents but also bring an environmental solution to a water problem, making water a fundamental component of the ecological chain.In three years from now, the smelly cloacal discharge that is the source of proliferation of mosquitos and rats affecting three million inhabitants will be a memory of the past. The interceptor will prevent sewage discharges from the centre and the south of the city into the Bogota river. TBMA Herrenknecht earth pressure balance tunnel boring machine commenced on 4th December, 2007 to bore the interceptor. The cutterhead diameter is 4,520 mm while the lined diameter is 3,750 mm. The test drive is going on and workers have moved it through about 10 metres of earth. The machine is expected to churn forward at about 22 metres per day on average. The interceptor will be built in 33 months. The tunnelling will remove clayey sands, silty sands and sands under a 12 m hydrostatic head while simultaneously laying 25 cm-thick segments of precast concrete. The machine erects five segments and a key to produce the rings. The cutter head equipped with cutting tools is driven by hydraulic and electric motors and hydraulic jacks push the head against the earth. Visit www.herrenknecht.com and www.riotunjuelo.gov.co 06/08.