Attch_11-Section_31_03_33-Removal_and_Control_of_Water_0004.pdf

Stampede Penstock and Butterfly Valve Rehab

Washoe Project, California Specifications No. 20-C0943

Removal and Control of Water

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SECTION 31 03 33

REMOVAL AND CONTROL OF WATER

PART 1 GENERAL

1.01 MEASUREMENT AND PAYMENT

A. Removal and Control of Water for 90 inch Outlet Works:

1. Payment: Lump sum price offered in price schedule

B. Delivery and Control of Water for Down River Minimum Flow Requirements:

1. Measurement: Volume of water pumped.

2. Payment: Unit price offered in the Price Schedule.

a. Volume shall not exceed volume determined by COR.

1.02 DEFINITIONS

A. Unwatering: Control and removal of ponded, seeping, or flowing surface water or emerging subsurface water from excavated surfaces and from precipitation within and adjacent to excavations and construction zones using channels, ditches, gravel drains, grave blankets, pipe, sumps, and discharge lines. Includes control and discharge of effluent waters.

1.03 SYSTEM DESCRIPTION

A. Design, install, operate, maintain, and monitor water transportation facilities for the 90-inch outlet work.

B. Design and lay out facilities to collect discharge water from water removal systems and convey water to designated approved discharge points.

C. Locate water removal facilities to maximize water removal and minimize construction interference.

D. Design, install, operate, maintain, and monitor water transportation from reservoir to down river.

E. Locate water removal facilities to maximize water removal and minimize construction interference.

F. Select pump types and design discharge systems.

1.04 SUBMITTALS

A. Submit in accordance with Section 01 33 00 - Submittals.

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B. RSN 31 03 33-1, Headgate Leakage Control Plan:

1. Equipment and materials.

a. Provide details on:

1) Piping:

a) Number of pipes.

b) Type.

c) Size.

d) Length.

e) Intake and discharge fittings.

f) Pipe location.

2) Pumping:

a) Pump size.

b) Number of pumps.

c) Capacity.

d) Power supply.

3) Miscellaneous Materials

2. Desing plans and methods.

a. Provide information on system:

1) Capacity.

2) Controls.

3) Discharge location and erosion protection.

4) Backup system

C. RSN 31 03 33-2, Water Delivery for River Minimum Flow Requirements:

1. Proposed method for transportation of water, i.e. pumping or siphoning, from reservoir to Little Truckee River downstream of Stampede Powerplant and Dam.

a. Equipment and materials.

1) Provide details on:

a) Piping:

i. Number of pipes.

ii. Type.

iii. Size.

iv. Length.

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v. Intake and discharge fittings.

vi. Pipe location.

b) Pumping:

i. Pump size.

ii. Number of pumps.

iii. Capacity.

iv. Power supply.

b. Desing plans and methods.

1) Provide information on system:

a) Capacity.

b) Controls.

c) Discharge location and erosion protection.

d) Backup system.

c. Calculation

1) Provide calculations showing designed system is capable of meeting cfs requirements.

2. The plan may be placed in operation upon approval, but nothing in this paragraph shall relieve the Contractor from full responsibility for meeting minimum river flow requirements.

D. RSN 33 03 33-3, River Temperature Recording:

1. Locations for river temperature monitoring devices to be approved by COR.

2. Logs for river temperatures.

1.05 REGULATORY REQUIREMENTS

A. Obtain required Federal, State, and local permits for water discharge and other activities associated with removal and control of water.

B. Refer to Section 01 57 30 – Water Pollution Control.

1.06 PROJECT CONDITIONS

A. Leakage occurs into the 90-inch outlet works from upstream headgate gate seals.

1. Anticipated leakage rate into outlet work pipe is up to 25 gallons per minute.

B. Little Truckee River minimum flow requirements.

1. 14-inch bypass line shall be operated by Bureau of Reclamation only.

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2. 14-inch bypass line will be used to provide a maximum of 15 cfs during outage to deliver water down river into the Little Truckee River.

3. Contractor shall provide equipment capable of supplying 30 cfs into Little Truckee River during outage of 90-inch Outlet Work pipe.

a. Contractor shall have system in place to notify if pumps or siphon shut off.

1) Contractor shall restore pumps or siphon to operating state within 1 hour.

b. Water intakes for siphons and/or pumps shall pull water from reservoir to maintain temperature of Little Truckee River between Stampede Dam and

Boca Dam. Temperature shall be between 45 Fahrenheit (F) and 65 F.

c. Contractor shall monitor water temperature at five (5) locations in the Little Truckee River between Stampede Dam and Boca Dam.

Temperature monitoring sites and depth to be determined by COR.

1) Devices shall be probe style with accuracy +/- 1.0 F.

d. Measurements for Little Truckee River flow rates will be measured at USGS gauge (10344400). River flow rates shall be maintained above 30 cfs.

e. Pumping or siphoning rates shall be determined by Little Truckee River flow rates and determined by COR.

f. Historical reservoir levels are provided in Section 51 00 20 – Reservoir Elevation Records.

g. Water pumped shall be pulled from a minimum of 20 ft below the reservoir surface.

PART 2 PRODUCTS

Not Used

PART 3 EXECUTION

3.01 REMOVAL OF WATER

A. Provide, maintain, and operate necessary facilities for removal of water from 90-inch outlet works, each penstocks, turbine pits and other parts of the work maintaining work free from water as required for performing work.

3.02 RIVER TEMPERATURE MONITORING

A. Contractor shall monitor water temperature at five (5) locations.

1. Locations for temperature measurement shall be as follows:

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a. One in or within 100 ft of the Stampede stilling basin.

b. One within 100 ft of Little Truckee River inlet to Boca Reservoir.

c. Three between Stampede Dam and Boca Reservoir to be approved by

COR Monitoring locations shall not be within 1.0 mile of each other.

B. Water temperature of Little Truckee River shall be maintained between 45 F and 65 F.

C. Temperature readings shall be taken at a minimum of once a day between 1:00 PM and 4:00 PM local time.

1. Temperature logs shall include location, time, and temperature.

3.03 UNWATERING

A. Use Contractor furnished pumps, sumps and pipes to lower and control water levels in advance of construction in the outlet work pipe.

B. Use sandbags, sand and gravel filter bedding, tarps, and other materials and techniques to control leakage.

3.04 INSTALLATION

A. Install Contractor-designed water control facilities just downstream of the headgate to eliminate or contain leakage. Install the water control facilities in accordance with the approved plans to prevent leakage past the water control facilities.

1. Contain all leakage past the headgate and direct flow away from the construction area to existing drains.

2. Work in the penstocks shall be performed in dry with no inflow from the reservoir.

B. Install Contractor-designed water transport system between Stampede Reservoir and

Little Truckee River via the existing concrete spillway. Install the water control facilities and transport in accordance with the approved plans to meet minimum river flow requirements.

C. Deliver water from Stampede Reservoir into Little Truckee River. Supplemented water amount provided by contractor shall not fall below 15 cfs.

3.05 MAINTENANCE

A. Maintain Contractor-installed water control facilities immediately downstream of the headgate while in place.

B. Maintain Contractor-installed water transport system delivering water from Stampede Reservoir to Little Truckee River.

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3.06 REMOVAL

A. After completing penstock rehabilitation, remove the Contractor-installed water control facilities just downstream of the headgate when no longer required as determined by

COR.

B. After completing penstock and valve work, and 90-inch outlet work is operational, remove the Contractor-installed water transport system when no longer required as determined by COR.

END OF SECTION