Friday, May 15, 2009

Site preparation, Environmental Protection and Landscaping Part 2

6. Notice of commencement

The Contractor shall give to the Engineer written notice of blasting operation. The works shall not be commenced until written approval has been received from the Engineer.

7. Environmental Protection and Landscaping
7.1. Discharge of water into existing streams

The Contractor shall make provision for the discharge or disposal from the Works and Temporary Works of all water and waste products however arising. The methods of disposal shall be to the satisfaction of the Engineer and of any authority or person having an interest in any land or watercourse over or in which water and waste products maybe so discharged. The requirements of this Clause shall not limit any of the Contractor’s obligations or liabilities.

7.2. Erosion and Sediment Control

The Contractor will undertake the following erosion and sedimentation control measures during the construction phase of the project.

Development of Drains and Dikes: catch and diversion drains shall be laid to ensure runoff from the construction works is directed into existing watercourses. All drains constructed will have a parabolic or trapezoidal cross-section. Interceptor dikes made of compacted material will be laid to convey water to stable outlets at non-erosive velocities. Dikes will have minimum ridge height of 0.5 m, minimum top width of 0.8 m and maximum side slopes 2:1 (horizontal to vertical).

Development of Bank: Sedimentation basins shall be constructed off-stream to remove sediment-laden runoff. The basins shall be located at points where the terrain provides maximum storage benefits. Desilting will be done when the capacity of the basin has been reduced by 30%. Effluent turbidity shall not exceed 200ppm.

Removal of vegetation and topsoil: Clearing shall be restricted to only those areas where the commencement of work is imminent. Clearing of areas not immediately required for the works shall be carried out at later time to suit the requirements of the construction program. Stockpile construction and maintenance – Smooth and free draining stockpile of removed topsoil shall be constructed with batter slopes not exceeding 1.5:1, and height limited to two meters. Compaction of the stockpile will be done by equipment necessary for the hauling, placing and spreading of the topsoil material. All topsoil stockpiles will be ripped to ensure the retention of moisture and the promotion of regrowth.

Resurfacing: a disturbed area that will be left exposed more than 30 days and not subject to any construction will receive temporary seeding. Following initial disturbance or rough grading, all critical areas subject to erosion (for example steep slopes) will receive temporary seeding in combination with straw or another suitable material.

Hugolina -