31 23 19 Dewatering.pdf
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- Attached to
- 2027 Sewer System Improvements Project
- Solicitation number
- Not on record
- Issued by
- Dauphin County, Harveys Lake Borough, Pennsylvania
About this file
This is a technical specification document for dewatering services prepared by Capital Region Water (CRW) for sewer system improvements projects in Harrisburg, Pennsylvania. The document outlines comprehensive dewatering and surface water control requirements for excavation and construction activities across multiple CRW facilities, including the Administrative Offices at 3003 N. Front Street, the Advanced Wastewater Treatment Facility at 1662 S. Cameron Street, and the Dr. Robert E. Young Water Services Center at 100 Pine Drive. The specification requires contractors to design and install dewatering systems capable of lowering the water table within excavation areas, relieving hydrostatic pressures in confined water-bearing strata, and preventing damage to adjacent properties and utilities. Contractors must also implement surface water control systems including ditches, berms, sumps, and pumping operations, with continuous operation required until backfilling is complete. The contractor bears full responsibility for system design, installation, operation, maintenance, and removal at no additional cost to the owner, and must comply with all applicable regulations from authorities having jurisdiction regarding water discharge and disposal.
The specification emphasizes contractor accountability for maintaining excavation stability, protecting existing infrastructure, and managing water disposal in an environmentally responsible manner. Contractors must conduct additional borings and investigations as required to complete system design at no additional cost and must notify the One Call System at least three working days before performing work to ensure underground utilities are properly located and marked. The contractor is required to immediately notify the engineer if the dewatering system cannot control water within the excavation and must not discontinue dewatering operations without written approval from the engineer. Water disposal requirements mandate that contractors evaluate site conditions, minimize erosion and sediment transport, discharge water to well-vegetated and stable areas, and remove pollutants and sediments prior to discharge using methods such as sedimentation tanks or pumped water filter bags. The contractor must repair any damage caused by dewatering operations or system failures to the satisfaction of both the engineer and owner.
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Text version
31 23 19 - Dewatering
1.0 General
1.1 Summary
A. Section Includes:
1. Dewatering system.
2. Surface water control system.
3. System operation and maintenance.
4. Water disposal.
1.2 References
A. ASTM International:
1. ASTM C33 - Standard Specification for Concrete Aggregates.
1.3 Definitions
A. Dewatering includes the following:
1. Lowering of ground water table and intercepting horizontal water seepage to prevent ground water from entering excavations and trenches.
2. Reducing piezometric pressure within strata to prevent failure or heaving of excavations and trenches.
3. Disposing of removed water.
B. Surface Water Control: Removal of surface water within open excavations.
1.4 System Description
A. The Contractor shall provide dewatering and surface water control systems, at the
Contractor’s opinion and cost, to permit Work to be completed on dry and stable subgrade.
1.5 Performance Requirements
A. The Contractor shall design dewatering systems to:
1. Lower water table within areas of excavation to permit Work to be completed on dry and stable subgrade.
2. Relieve hydrostatic pressures in confined water bearing strata below excavation to eliminate risk of uplift or other instability of excavation.
3. Prevent damage to adjacent properties, buildings, structures, utilities, and facilities from construction operations.
4. Prevent loss of fines, quick condition, or softening of foundation subgrade.
5. Maintain stability of sides and bottoms of excavations and trenches.
B. The Contractor shall design surface water control systems to:
1. Collect and remove surface water and seepage entering excavation.
1.6 Quality Assurance
A. The Contractor shall comply with authorities having jurisdiction (AHJ) for the following:
1. Water discharge and disposal from pumping operations.
1.7 Coordination
A. Section 01 31 13 – Project Coordination: Requirements for coordination.
B. The Contractor shall coordinate Work to permit the following construction operations to be completed on dry stable substrate.
2.0 Products
2.1 Dewatering Equipment
A. The Contractor shall select dewatering equipment to meet specified performance requirements for the Project. Consult Engineer for additional details, if required.
2.2 Accessories
A. Valves and Fittings: The Contractor shall furnish valves and fittings to isolate each dewatering well from header pipe and to prevent loss of pump prime.
3.0 Execution
3.1 Examination
A. Section 01 73 00 - Execution Requirements: The Contractor shall verify existing conditions before starting Work.
B. The Contractor shall conduct additional borings and investigations as required to complete dewatering system design, at no additional cost to the Owner.
C. The Contractor shall notify the One Call System not less than three working days before performing Work:
1. Request underground utilities to be located and marked within and surrounding construction areas.
3.2 Preparation
A. The Contractor shall protect existing adjacent buildings, structures, and improvements from damage caused by dewatering operations.
3.3 Dewatering System
A. The Contractor shall install dewatering system in accordance with shop drawings.
B. The Contractor shall locate system components to allow continuous dewatering operations without interfering with installation of permanent Work and existing public rights-of-way, sidewalks, and adjacent buildings, structures, and improvements.
3.4 Surface Water Control System
A. The Contractor shall provide ditches, berms, and other devices to divert and drain surface water from excavation area.
B. The Contractor shall divert surface water and seepage water within excavation areas into sumps and pump water into drainage channels in accordance with requirements of agencies having jurisdiction.
C. The Contractor shall control and remove unanticipated water seepage into excavation.
3.5 System Operation and Maintenance
A. The Contractor shall operate dewatering system continuously until backfilling is complete.
B. When dewatering system cannot control water within excavation, the Contractor shall immediately notify Engineer and stop excavation work:
1. Supplement or modify dewatering system and provide other remedial measures to control water within excavation.
2. Demonstrate dewatering system operation complies with performance requirements before resuming excavation operations.
C. The Contractor shall modify dewatering and surface water control systems when operation causes or threatens to cause damage to new construction, existing site improvements, adjacent property, or adjacent water wells.
D. The Contractor shall correct unanticipated pressure conditions affecting dewatering system performance.
E. The Contractor shall not discontinue dewatering operations without Engineer's written approval.
3.6 Water Disposal
A. Prior to dewatering, the Contractor shall evaluate site conditions. Evaluate flow path to minimize erosion and the transport of sediment to storm drains and receiving waters.
B. The Contractor shall discharge water to areas that are well vegetated and stable.
Pollutants and sediments must be removed prior to discharging to a storm drain, waterbody, or wetland. This may include the use of a pumped water filter bag.
C. The Contractor shall dispose of water removed by dewatering in a manner that does not endanger public health, property, and portions of the work under construction or completed. Dispose of water in a manner that avoids inconvenience to others. Provide sumps, sedimentation tanks, pumped water filter bags, and other flow control devices as required.
3.7 System Removal
A. The Contractor shall remove dewatering and surface water control systems after dewatering operations are discontinued.
B. The Contractor shall repair damage caused by dewatering and surface water control systems or resulting from failure of systems to protect property, to the satisfaction of the Engineer and Owner.
END OF SECTION
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