Padma Multipurpose Bridge Project

Figure 8-4: Maximum size of Charland reclamation area if all dredged material from south bank RTWis used for reclamation39. Possible locations of the Charland identified near the Project for dredge material disposals areshown inFigure 8-4. Two Charland located in the Project area, one near Mawa (Medinimondal Char) and theother near Janjira (Majirkandi Char), are identified for dredge material disposal. Total area of thesetwo Charland is 1,273 ha (1220 near Janjira and 53 near Mawa). These two Charland can hold avolume of 25 M m3 of dredge material per season with an average filling height of 2m.40. Consultations held with local population including local government and community leaders arethe key inputs for the identification of these Charland. These Charland are recently formed andpresently not in use.41. The other possible better uses of dredged materials are to create flood-free areas as part ofconstruction and to partly refill the dredged trench after completion of the protection works. Refillingthe trench often completion of the protection works provides additional stability to the trench slopesearly after completion of the revetment. This would also prevent the river from immediately being“drawn” to as deep unfilled trench after the temporary protection is removed at the upstream end.However, refilling the trench will require longer pumping distances, more pumping power with boosterstations and long pipelines, all of which increases the cost.8.5.4 Method of Reclamation/Disposal42. The wording “reclamation area” is used whenever the dredged material is considered as useful fillmaterial; the reclamation area may be either the final destination or a stockpile area. In principle, bothbunded/closed and open reclamation areas are possible, but mostly they are expected to bebunded/closed, with a water outlet weir box at its downstream end. Bunding is under taken then withhydraulic excavators using nearby surface material. Bund heights can be raised as necessary usingdredged material.43. The weir box can be used to control the water level in the reclamation area. Adjusting the weirallows control of the setting process in the reclamation area. Both fill quality requirements (density,grading and fines content, homogeneity) and turbidity requirements to the surrounding waters can bemanaged.8-38