Padma Multipurpose Bridge Project

NameLarge TreeFrogIndian BullFrogIUCN/CITESStatusVulnerableCITES II7.2.2 Construction Stage7.2.2.1 Main BridgeLocalStatusUncommonResidentCommonResidentLocal NameBaro GechoBangNumber Location Sighted PotentialSighted 1 Impact2 Charland both u/sand d/s and otherwetlandsSona Bang 26 Charland both u/sand d/s and otherwetlandsSource: Consultant’s Bi-monthly Survey, 2009-2010.Minor impactMinor impact12. Construction of main bridge will involve the following major activities, which will result in bothpotential significant negative and positive impacts: Mobilization of equipments and vehicles, transport of construction materials Dredging of channels to bring barges Movement of barges on the river Construction of sub-structure (pile driving, sediment disposal) Construction of superstructure (construction staging) Disposal of wastesPile Driving Activities in the Main Bridge13. The main bridge will have 42 piers with a span length of 150m. The foundation of each pierrequires installation of 8 steel piles of 3 m diameter to a depth of 130 m through pile driving. The totalnumber of piles to be installed is 336.14. Piles would be installed by a crane mounted on a barge and vibrated to depth as far as possible.Material inside the pile would be removed to assist driving by a hydraulic rotary drilling rig or air liftedby crane mounted equipment. On completion of driving, piles would be backfilled with a cement sandmix, delivered to site in transit mixers on roll on – roll off barges. It is envisaged that there will be atleast two piling crews established to maintain the proposed program. The construction program of thebridge is given in Figure 7-4 and total construction period of the foundation is about 28 months.Figure 7-4: Tentative Schedule of the Piling Driving ActivitiesExperience from Jamuna Bridge Project15. The foundation of the Jamuna Bridge comprises 121 numbers of 2.5 to 3.5 m diameter, 80 mlong piles. The piles were installed using a Menck MHU hydraulic hammer with a 1,700 kN-M energy.Such pile driving easily produces noise levels of about peak 205 dB, RMS 200 dB and SEC 180 dB ata distance of 100 m (Figure 7-5). No mitigation measures to reduce sound levels were adopted during7-8