Surface water control

(1) The Contractor shall be fully responsible for designing all features of the system for unwatering the excavation and controlling surface water that may fall into the excavation. The sump pumping system shall be designed with sufficient storage and pumping ca­pacity to prevent flooding the bottom of the excava­tion for the dam for at least a 1 in lo-year rainfall in­tensity, assuming 100 percent runoff, for the follow­ing periods:

Period 30 minutes

1 hour

2 hours

In any event, the Contractor shall be responsible for controlling whatever surface runoff occurs, regardless of rainfall intensity, so as to protect the area for pile driving and testing from flooding.

(2) The Contractor shall submit for approval with­in 15 calendar days, after he or she has received a No­tice to Proceed, drawings, design data, and charac­teristics of the equipment he proposes to utilize in unwatering and controlling surface water. The data

and drawings to be submitted shall include, but not necessarily be limited to:

(a) Location and size of sumps, pumps, and


(b) Height and elevation of dike around excavation.

(c) Characteristics of sump pumps and horsepower of engines.

(d) Location and size of discharge piping. (Sur­face water shall not be pumped into the discharge header for the dewatering (well) sys­tem.) g. Dewatering perched groundwater in lower part or bottom of excavation. The Contractor shall be fully responsible for design and installation of any sup­plemental dewatering facilities that may be required to control any seepage or groundwater in the bottom or lower part of the excavation in order to assure a sta­ble subbase and permit work to be conducted in the “dry.” These supplemental measures may include well – points, sand drains, French drains, and appropriate pumps, piping, and appurtenances as necessary and approved by the C. O.R. subject to satisfactory perfor­mance of the facility installed. Pay for any such sup­plemental dewatering, if required, for the lower or bot­tom part of the excavation should be included in the price for excavation. There will be no charges or claims for extra compensation or time extension for any sup­plemental dewatering performed in the bottom or lower part of the excavation.