SECTION_31_23_19_-_Dewatering_R1_0004.pdf

BUREAU OF INDIAN AFFAIRS OGLALA DAM SPILLWAY AND OUTLET WORKS

OGLALA DAM SPILLWAY AND OUTLET WORKS SECTION 31 23 19

JUNE 2023 DEWATERING

FOR BID REV 1 PAGE 1 OF 4

SECTION 31 23 19

DEWATERING

GENERAL

1.01 SCOPE OF WORK

A. This Section specifies the requirements for the following general items of Work:

Design water control systems for the management, collection, and disposal of reservoir water, tailwater, groundwater or surface water for the proper construction of all Work.

It is anticipated that the existing outlet works will be utilized to divert flood flows during Phase 1 construction, and the new outlet works will be utilized to divert flood flows during Phase 2 construction.

Install and maintain pumps, piping, drains, channels, well points, wells, and other facilities for the control, collection, and disposal of groundwater for the proper construction of all Work.

Maintain prepared foundations and all other parts of the Work free from seepage or standing water as required for constructing each part of the Work.

Protect claystone bedrock from saturation from groundwater and surface water during excavation and subgrade preparation.

Comply with all applicable environmental protection laws and requirements in operation of the dewatering system and disposal of collected water.

Remove all components of the dewatering systems when no longer required.

1.02 SUBMITTALS

A. Shop Drawings

Submit a Dewatering Plan at least 14 days prior to mobilization for review and approval by the BIA Representative, including the following requirements:

a. Prepared and stamped by a Registered Professional Engineer with experience in design of dewatering systems and control of water for dam construction projects.

b. Drawings and narrative that provide details regarding anticipated types, sizes, capacities, and locations of water control structures, piping, facilities, and calculations to substantiate designs and selected facilities.

c. Drawings and narrative that describe all supplemental dewatering facilities, such as supplemental drainage channels, sedimentation ponds (if required), and silt barriers.

d. Expected discharge volumes from each water control system and points of discharge.

BUREAU OF INDIAN AFFAIRS SECTION 31 23 19

JUNE 2023 DEWATERING

FOR BID REV 1 PAGE 2 OF 4

e. Methods and procedures to fill openings and voids left by removal of the dewatering system.

B. Administrative

Acquire, maintain, and submit copies of discharge permits as required by Federal and state agencies in accordance with Section 01 57 01 – Permitting Requirements and Environmental Controls.

Acquire, maintain, and submit copies of South Dakota Department of Health Well Permit Documents (if required) in accordance with Section 01 57 01 – Permitting Requirements and Environmental Controls.

PRODUCTS

2.01 DEWATERING SYSTEM

A. Specially designed water collection sumps, trenches, or well points for collecting surface water and reservoir water.

B. Pumps and piping to convey and remove collected water.

EXECUTION

3.01 GENERAL

A. Review available topographic, subsurface, and hydrogeologic data for the Project site.

B. Maintain a dry work environment by use of constructed cofferdam during construction in accordance with Section 01 50 00 – Temporary Facilities and Controls.

3.02 INSTALLATION AND OPERATION

A. Install sumps, ditches, and pump systems to control inflow of surface water to excavations, prevent localized ponding of water in construction site, and to collect seepage flows from valley slopes or excavation slopes.

B. Locate every element of dewatering systems to avoid interference with excavation and construction activities.

Do not allow water to accumulate in Work areas until affected Work is satisfactorily constructed.

Prevent damage to facilities, foundations, and surrounding areas and structures.

Perform dewatering operations so that no disturbance to the bearing units and to soil supporting Work will result.

Prevent loss of fines, boiling, quick conditions, or softening of foundation strata.

JUNE 2023 DEWATERING

FOR BID REV 1 PAGE 3 OF 4

Maintain stability of excavation slopes and bottom of excavation so that every phase of Work can be performed safely and in the dry.

C. If the water management and dewatering system does not meet the specified requirements:

Restore the system to meet specified requirements and improve the system if necessary.

Repair resulting damage to Work, to the satisfaction of the BIA Representative, at no cost to the COR and the BIA Representative.

3.03 REMOVAL

A. Remove all elements of the dewatering systems from Site upon completion of the affected Work in accordance with Section 01 50 00 – Temporary Facilities and Controls.

B. Remove crushed stone or coarse fill materials from dewatering trenches and sumps.

Backfill these areas with Class E or F concrete or grout based on the size of the area to be filled. Alternative methods of completely grouting coarse fill materials in dewatering areas may be proposed but are subject to review and approval by the COR and the BIA Representative.

C. Grout all voids in rock left as a result of the dewatering system.

END OF SECTION

JUNE 2023 DEWATERING

FOR BID REV 1 PAGE 4 OF 4

THIS PAGE INTENTIONALLY LEFT BLANK