Technical_Specifications_for_Dredging_and_Sediment_Removal_-260817.pdf

TECHNICAL SPECIFICATION

FOR

Charles County Government

Department of Public Works

Wheatley Dam Dredging Project

Charles County Project No. 23-32

Langan Engineering and Environmental Services LLC

1300 Wilson Boulevard

Arlington, VA 22209

July 2026

SECTION 02480

DREDGING AND SEDIMENT REMOVAL

PART 1 - GENERAL

1.1 Project Overview and Scope of Work

The Work includes furnishing all labor, materials, equipment, and incidentals necessary to perform mechanical dredging and sediment removal within

Wheatley Reservoir for the purpose of restoring reservoir storage capacity and maintaining the long-term performance of Wheatley Dam. The project consists of mechanically removing accumulated sediment from the designated dredge areas, temporarily staging and dewatering the material within designated shoreline dewatering areas, transporting the dewatered sediment to a County-

Designated Sediment Placement Area adjacent to the Charles County Landfill, constructing a stable sediment stockpile, and restoring all disturbed areas upon completion of the Work.

The County intends to retain the dredged sediment for future beneficial use as landfill cap material. Accordingly, the Contractor shall handle, transport, place, and manage the dredged sediment in a manner that preserves its suitability for its intended future use. The final location of the County-Designated Sediment

Placement Area will be established during the preconstruction meeting in coordination with the Owner, the Engineer, Charles County Department of

Public Works, and representatives of the Charles County Landfill.

The Work generally includes, but is not limited to, the following:

1. Mobilization and demobilization of dredging equipment, support equipment, personnel, and temporary facilities.

2. Mechanical dredging and removal of accumulated sediment and incidental debris within the limits shown on the Contract Drawings.

3. Temporary staging and dewatering of dredged sediment within the designated shoreline dewatering areas.

4. Loading, hauling, and placement of dewatered sediment within the County-

Designated Sediment Placement Area adjacent to the Charles County

Landfill.

5. Construction and maintenance of the sediment stockpile, including grading, lift placement, drainage, and erosion and sediment control measures.

6. Implementation and maintenance of erosion and sediment control measures, turbidity control measures, and all other environmental protection requirements as required by Maryland Department of the

Environment and Charles County Soil Conservation District .

7. Site restoration, stabilization, and cleanup of all disturbed areas.

All Work shall be performed in accordance with the Contract Documents and all applicable federal, state, and local permits and regulations, including permit requirements administered by the Maryland Department of the Environment

(MDE) and the U.S. Army Corps of Engineers (USACE).

1.2 Location and Site Description

A. The project is located at Wheatley Reservoir, an impoundment with an approximate normal pool storage volume of 2,454 acre-feet located near La Plata in Charles County, Maryland. The reservoir is a non-tidal freshwater waterbody formed by Wheatley Dam; an earthen embankment regulated by the Maryland

Department of the Environment (MDE) Dam Safety Division, MDE Dam #060.

The drainage area feeding the reservoir encompasses roughly 1,832 acres, and the reservoir discharges south through a reinforced concrete principal spillway pipe to tributaries of the Gilford creek watershed.

B. The normal pool elevation of the reservoir is approximately 95 feet (NAVD 88), with a minimum pool elevation of about 92.5 feet. The water level at the time of the December 2024 bathymetric survey was about two feet below normal due to dry seasonal conditions.

C. The bathymetric and sub-bottom profiling surveys conducted in 2024 identified significant sediment accumulation in the northern and western portions of the reservoir. Manual sediment probing confirmed unconsolidated deposits averaging 1 to 2 feet in thickness in most areas, with thicker deposits (greater than 2 feet) found in the upper north and western lagoon areas. In contrast, the central and southern basins near the dam contain only a thin surface layer of fine material, indicating that much of the original reservoir bottom remains exposed or covered by partially consolidated sediment. Some localized “crunchy” resistance was reported in the probe logs, suggesting layers of cohesive or compacted material beneath the upper silt layer.

D. The sediment composition is inferred from acoustic attenuation and probe feedback to be fine-grained silt and organic matter, with minimal sand content.

The material exhibits high water content and poor strength in shallow deposits, consistent with organic accumulation over time. Due to its fine texture, sediment in the southern basin may be partially transported through the principal spillway during high-flow events, potentially contributing to a gradual loss of reservoir storage capacity.

E. The surrounding property is composed primarily of wooded parkland and open space managed by Charles County. All work shall be performed in a manner that protects adjacent natural resources and prevents the release of sediment or turbidity into downstream waters. The Contractor shall maintain compliance with all applicable MDE Wetlands and Waterways, Water Quality, and Erosion and

Sediment Control permit requirements throughout the dredging operations.

1.3 Applicable Regulations and Permits

The Contractor shall perform all work in compliance with the following, including the most recent versions:

1. MDE Wetlands and Waterways, Nontidal, and Dam Safety regulations

(COMAR 26.17 and 26.23).

2. USACE Clean Water Act Section 404 and MDSPGP-6 Authorization for

Minor Dredging.

3. NPDES General Permit for Construction Activity (No. 23GP).

4. Maryland Standards and Specifications for Soil Erosion and Sediment

Control.

The Owner has obtained, or will obtain, all permits identified in the Contract

Documents that are the responsibility of the Owner. The Contractor shall comply with all permit conditions and shall obtain any permits or approvals required for the Contractor's means and methods of construction.

1.4 Contractor Qualifications and Coordination

A. Contractor Qualifications

The Contractor shall demonstrate experience performing mechanical dredging and sediment removal projects of similar scope and complexity. At a minimum, the Contractor shall have successfully completed at least three (3) comparable dredging or sediment removal projects within the past five (5) years involving mechanical excavation, sediment handling, dewatering, hauling, and placement or disposal of dredged material. As part of the Dredging Operations Plan, the

Contractor shall submit the following:

1. A list of at least three (3) comparable projects, including project name, owner, location, approximate dredged volume, and completion date.

2. Owner references with current contact information.

3. A list of major dredging, hauling, and support equipment proposed for the

Work.

B. Preconstruction Coordination

Prior to mobilization, the Owner will conduct a preconstruction meeting attended by the Contractor, the Engineer, representatives of the Charles County

Department of Public Works, representatives from Department of Recreation, Parks & Tourism, and representatives of the Charles County Landfill.

The purpose of the meeting is to review the project schedule, dredging sequence, temporary shoreline dewatering operations, hauling procedures, environmental protection requirements, traffic control, site access, and sediment placement operations. During the meeting, the County will identify the County-

Designated Sediment Placement Area and communicate any operational requirements or restrictions associated with access, placement, and stockpile construction.

The Contractor shall incorporate the information discussed during the preconstruction meeting into the Dredging Operations Plan prior to commencing dredging activities.

The Contractor shall coordinate all site access, dredging operations, hauling activities, and environmental protection measures with the Owner, the Engineer, and Maryland Department of the Environment throughout the Work and shall provide the Owner and Engineer with a minimum of seventy-two (72) hours' notice prior to the commencement of dredging operations.

1.5 Submittals

A. The Contractor shall prepare and submit all documentation necessary to demonstrate compliance with this Specification, the Contract Drawings, and applicable permit requirements. All submittals shall be transmitted to the

Engineer for review and approval prior to commencement of the associated work activity. Submittals shall be complete, clearly identified, and include all supporting information necessary for review. Submittals should reference the exact specification section including number, subheading, and paragraph as necessary to expedite the review process.

B. The following submittals shall be provided and approved prior to mobilization or commencement of dredging activities:

1. Dredging Operations Plan – A written plan describing the Contractor's proposed means and methods for completing the Work. At a minimum, the plan shall include:

a. Proposed dredging equipment and support equipment.

b. Sequence of dredging operations.

c. Estimated production rates and project schedule.

d. Temporary shoreline dewatering and staging procedures, including the anticipated duration of sediment dewatering.

e. Methods for loading, hauling, transporting, and placing dredged sediment within the County-Designated Sediment Placement Area.

f. Truck loading procedures, including the method used to establish the certified truck box volume or designated fill line for quantity measurement.

g. Proposed erosion and sediment control measures necessary to supplement the Contract Drawings during construction.

h. Procedures for minimizing turbidity, controlling sediment, preventing fuel or hydraulic fluid releases, and maintaining environmental compliance throughout the Work.

2. Project Schedule – A construction schedule identifying the anticipated mobilization, dredging, temporary dewatering, hauling, sediment placement, restoration, and demobilization activities including start date, anticipated duration, and anticipated end date of each activity.

3. Traffic Control Plan – A plan describing proposed haul routes, traffic control measures, construction access, and procedures for maintaining safe vehicle movement throughout the project.

4. Equipment List – A list of the major dredging, hauling, dewatering, and support equipment to be used for the Work.

5. Health and Safety Plan – A site-specific Health and Safety Plan meeting applicable OSHA requirements for construction activities, including over -water work, equipment operation, and worker protection.

C. Construction Phase Submittals

1. Daily Dredging and Hauling Logs – Daily records documenting the approximate quantity of sediment dredged, dredging locations, temporary dewatering activities, number of truckloads hauled, estimated hauled volume, placement activities, weather conditions, and any significant operational issues encountered during the Work.

2. Incident Reports – Documentation of spills, permit deviations, equipment failures resulting in environmental impacts, or other significant incidents shall be submitted to the Engineer within twenty-four (24) hours of occurrence.

D. Closeout Submittals

1. Final Quantity Summary – A summary of the total dredged volume based on the approved method of quantity measurement established under this

Specification.

2. Daily Hauling Log Summary – A compilation of the daily hauling records documenting the total number of truckloads, estimated delivered volumes, and dates of placement within the County-Designated Sediment Placement

Area.

3. Site Restoration Certification – Documentation confirming that all disturbed areas have been restored, stabilized, and permanently protected in accordance with the Contract Documents. Certification shall include photographs from before and after the Work documenting adequate restoration of the surrounding site.

4. Permit Closeout Documentation – Copies of all documentation, certifications, monitoring records, or other information required for permit compliance and project closeout.

1.6 Environmental Protection and Safety Requirements

The Contractor shall conduct all Work in a manner that protects the reservoir, adjacent wetlands, surrounding parkland, and other natural resources from unnecessary disturbance. The Contractor shall implement all reasonable measures necessary to prevent turbidity, sediment migration, fuel or hydraulic fluid releases, and other environmental impacts throughout the duration of the

Work. The Contractor shall immediately correct any condition that could adversely affect water quality, public safety, or environmental resources.

The Contractor shall comply with all applicable federal, state, and local safety regulations, permit conditions, and environmental requirements throughout the project.

At a minimum, the Contractor shall comply with the following requirements:

1. Conduct all dredging, hauling, dewatering, and sediment placement operations in a manner that minimizes turbidity and prevents the uncontrolled release of sediment into the reservoir or adjacent waters.

2. Maintain all erosion and sediment control measures in accordance with the

Contract Drawings and this Specification. The Contractor shall inspect these measures daily and promptly repair or replace any damaged or ineffective controls by end of day.

3. Fueling, lubrication, and equipment maintenance should be performed onshore whenever practicable and in a manner that prevents the release of fuel, oil, hydraulic fluid, grease, or other hazardous materials to the reservoir or surrounding environment.

4. Spill containment materials appropriate for the equipment being operated shall be maintained on all dredging equipment, support vessels, and fueling equipment. Any release of fuel, oil, hydraulic fluid, or other hazardous material shall be immediately contained, cleaned, and reported to the

Owner and Engineer.

5. Equipment shall be maintained in good operating condition and routinely inspected for leaks or mechanical deficiencies that could result in environmental impacts.

6. Work shall comply with the applicable requirements of OSHA 29 CFR 1926 for construction activities. Floating equipment, barges, and work platforms shall also comply with applicable U.S. Coast Guard requirements.

7. The Contractor shall conduct all operations in a manner that minimizes disturbance to adjacent wetlands, vegetation, wildlife habitat, and existing public facilities. Equipment, materials, and temporary stockpiles shall remain within the approved work limits shown on the Contract Drawings unless otherwise approved by the Engineer through written submittal.

8. Any damage to existing facilities, roadways, utilities, park property, erosion and sediment control measures, or environmentally sensitive areas resulting from the Contractor's operations shall be repaired or restored by the Contractor at no additional cost to the Owner.

9. The Contractor shall maintain the work site in a clean and orderly condition throughout construction and shall remove waste materials, debris, and unused construction materials on a regular basis to minimize environmental impacts and maintain safe working conditions.

1.7 Measurement and Payment Basis

Payment for dredging and sediment removal shall be based on the Contract unit price for dredged sediment, measured in cubic yards. The Contract unit price shall constitute full compensation for furnishing all labor, materials, equipment, tools, incidentals, supervision, transportation, and services necessary to complete the Work in accordance with the Contract Documents.

The unit price for dredging and sediment removal shall include, but not be limited to, the following:

1. Mobilization and demobilization of personnel, equipment, and temporary facilities.

2. Mechanical dredging and removal of sediment and incidental debris within the limits shown on the Contract Drawings.

3. Temporary staging and dewatering of dredged sediment within the designated shoreline dewatering areas.

4. Loading, hauling, transporting, unloading, placing, grading, and maintaining the dredged sediment within the County-Designated Sediment Placement

Area.

5. Construction and maintenance of sediment stockpiles, including placement in lifts, grading, drainage, and erosion and sediment control measures.

6. Furnishing, installation, maintenance, and removal of all temporary erosion and sediment control measures required to complete the Work.

7. Protection of existing facilities and restoration of disturbed areas resulting from the Contractor's operations.

8. Daily documentation, hauling logs, quantity records, and all other records required by this Specification.

9. Compliance with all applicable permit conditions, environmental protection requirements, and safety requirements.

The basis for determining measured quantities shall be the verified volume of dredged sediment transported to the County-Designated Sediment Placement

Area as documented in accordance with Section 3.9, Measurement, Documentation, and Quantity Verification.

Mobilization, demobilization, and site restoration shall be paid in accordance with the Bid Schedule. No separate payment will be made for temporary dewatering, sediment handling, hauling, stockpile construction, erosion and sediment control, environmental protection measures, variations in sediment moisture content, delays associated with dewatering, or any other work incidental to completion of the dredging operations.

PART 2 – MATERIALS AND DISPOSAL

2.1 Description of Sediment to be Removed

A. The material to be removed under this Contract consists of accumulated fine -grained sediments and organic deposits that have settled within Wheatley

Reservoir since its original impoundment. The dredging area for this initial task includes the northern arm and western lagoons of the reservoir, where significant sediment deposition has occurred due to inflow transport and low circulation. The dredging limits are defined on the Contract Drawings.

B. Sediment Characteristics

1. Based on the 2024 bathymetric and sub-bottom profiling surveys and manual sediment probing, the accumulated sediment generally consists of soft, unconsolidated silts with moderate to high organic content and occasional fine clay layers.

2. Sediment thickness varies across the reservoir, ranging from 1 to 2 feet throughout most of the dredge area, with thicker deposits exceeding 2 feet in some areas.

3. Acoustic attenuation and field probing results suggest the underlying native substrate consists of dense silt or clay forming a distinct “hard bottom,” which shall not be disturbed during dredging.

C. Debris and Obstructions

1. Limited submerged debris, vegetation, and organic material (e.g., branches, roots, and leaves) were observed in the surveyed areas.

2. The Contractor shall remove incidental debris encountered during dredging and dispose of it at an approved off-site facility.

3. Should the Contractor encounter large obstructions such as stumps, boulders, or buried structures not identified in the Contract Documents, the

Contractor shall notify the Engineer and proceed with dredging in another location within the designated dredging area.

2.2 Sediment Characterization

The Owner has performed laboratory testing and characterization of the reservoir sediments to support this project. The sediment analytical testing report is included as an appendix to these Specifications and shall be used by the Contractor for bidding purposes.

The Contractor shall handle, transport, and place the dredged sediment in accordance with these Specifications and any operational requirements established during the preconstruction meeting. No additional sediment characterization or analytical testing shall be required unless directed by the Owner or as required due to changes in the scope of Work.

2.3 Temporary Shoreline Dewatering and Staging Areas

A. General

The Contract Drawings identify two temporary shoreline dewatering and staging areas for use during dredging operations. These areas are provided to allow the

Contractor to temporarily stage, dewater, and manage dredged sediment prior to loading and transport to the County-Designated Sediment Placement Area. The

Contractor may utilize either or both designated dewatering areas as necessary to support the proposed sequence of operations.

The Contractor shall be solely responsible for coordinating dredging, dewatering, hauling, and sediment placement operations to ensure sufficient capacity is maintained within the temporary dewatering areas throughout the duration of the

Work.

B. Permitted Uses

The temporary shoreline dewatering and staging areas may be used for the following activities:

1. Temporary stockpiling of freshly dredged sediment.

2. Gravity dewatering of dredged sediment.

3. Spreading, turning, reshaping, or consolidating sediment to promote drainage and drying.

4. Temporary staging of sediment prior to loading into haul trucks.

5. Loading of dewatered sediment for transport to the County-Designated

Sediment Placement Area.

No material shall remain within the temporary dewatering areas following completion of the Work unless otherwise directed by the Owner.

C. Dewatering Requirements

Prior to loading for transport, dredged sediment shall satisfy the following minimum dewatering criteria:

1. No free water shall drain from the bucket during loading.

2. Sediment shall be sufficiently dewatered to prevent runoff or leakage during transport.

3. Sediment shall support loading equipment without excessive pumping, rutting, or instability.

4. Sediment shall be capable of being safely hauled and placed in stable lifts within the County-Designated Sediment Placement Area.

D. Water Management

The Contractor shall maintain the temporary dewatering areas to prevent the uncontrolled release of sediment-laden water. Return water generated during dewatering shall remain within the approved erosion and sediment control measures shown on the Contract Drawings. The Contractor shall maintain positive drainage within the dewatering areas and promptly repair any erosion, damage, or deficiencies in the erosion and sediment control measures.

E. Maintenance

The Contractor shall maintain the temporary dewatering and staging areas in a safe, orderly, and serviceable condition throughout construction. Sediment shall be managed to maintain adequate capacity for ongoing dredging operations, and haul routes within the dewatering areas shall be maintained to safely accommodate construction traffic.

Upon completion of dredging operations, all remaining sediment shall be removed from the temporary dewatering areas, and the areas shall be graded, stabilized, and restored in accordance with the Contract Drawings and these Specifications.

F. Modifications to Temporary Dewatering Areas

The temporary shoreline dewatering and staging areas shown on the Contract

Drawings have been established to accommodate the anticipated dredging operations. The Contractor may propose modifications to the configuration , size, or location of the designated dewatering areas, or may request the use of additional temporary dewatering or staging areas, provided such modifications support the

Contractor's proposed means and methods and do not adversely impact the reservoir, adjacent wetlands, park property, or other environmental resources.

Any proposed modifications or additional temporary dewatering or staging areas shall be submitted to the Engineer for review and shall require written approval from the Owner prior to implementation.

Approval of a proposed modification shall not relieve the Contractor of responsibility for maintaining environmental protection measures, erosion and sediment controls, site restoration, or compliance with the Contract Documents.

No additional compensation shall be provided for modifications proposed solely for the Contractor's convenience or means and methods.

2.4 County-Designated Sediment Placement Area

A. General

Following temporary shoreline dewatering, dredged sediment shall be transported to the County-Designated Sediment Placement Area for final placement and stockpiling. The County-Designated Sediment Placement Area will be identified during the preconstruction meeting and shall be used for all dredged sediment generated under this Contract unless otherwise directed by the Owner.

The County intends to retain the dredged sediment within the designated placement area for future beneficial use as landfill cap material. The Contractor shall place and manage the sediment in a manner that preserves its suitability for this intended future use.

B. Sediment Placement Requirements

The Contractor shall place dredged sediment in a controlled and systematic manner to produce a stable, well-drained stockpile. Sediment shall be placed in uniform lifts and graded as placement progresses to promote drainage and maintain safe working conditions.

At a minimum, the Contractor shall comply with the following requirements:

1. Sediment shall be placed in lifts not exceeding 12 inches in thickness.

2. The completed stockpile shall not exceed a maximum height of 20 feet above existing grade.

3. Side slopes shall not be steeper than 3H:1V, unless otherwise approved by the Owner.

4. Positive drainage shall be maintained throughout the placement area to prevent prolonged ponding of water.

5. Sediment shall not be placed outside the approved limits established by the

Owner.

6. The Contractor shall maintain safe access for construction equipment throughout placement operations.

C. Stockpile Management

The Contractor shall continuously manage the stockpile to maintain stability, drainage, and erosion control throughout construction. Sediment may be spread, graded, reshaped, or consolidated as necessary to maintain the approved stockpile configuration and accommodate ongoing hauling operations.

The Contractor shall coordinate hauling operations with stockpile construction so that placement activities do not interfere with safe vehicle movement or exceed the available capacity of the placement area.

D. Erosion and Sediment Control

The Contractor shall install, maintain, and modify erosion and sediment control measures as necessary to prevent sediment migration from the County-Designated

Sediment Placement Area. Any erosion, sediment migration, or damage resulting from placement operations shall be immediately corrected by the Contractor at no additional cost to the Owner.

Runoff from the placement area shall be managed in accordance with the approved erosion and sediment control measures and applicable permit requirements.

E. Maintenance and Cleanup

The Contractor shall maintain the County-Designated Sediment Placement Area in a safe, orderly, and serviceable condition throughout the duration of the Work.

Upon completion of sediment placement operations, the Contractor shall leave the stockpile in the configuration approved by the Owner, remove construction debris and excess materials, restore temporary access routes as required, and stabilize all disturbed areas associated with the placement operations.

2.5 Erosion and Sediment Control Materials

A. General Requirements

The Contractor shall furnish, install, and maintain all erosion and sediment control

(E&S) materials necessary to prevent sediment migration, turbidity, or off -site runoff from dredging, dewatering, and material handling operations.

All materials and installations shall conform to the Maryland Standards and

Specifications for Soil Erosion and Sediment Control (latest edition) and the project’s approved Erosion and Sediment Control Plan. Where this Specification is silent, the Maryland standards shall govern.

B. Materials and Installation

E&S materials may include silt fence, super silt fence, compost filter logs, straw bales, turbidity curtains, and other measures as required by the site-specific plan.

The Contractor shall install each device per the Maryland standards and maintain it in good condition until disturbed areas are stabilized. Sediment shall be removed when accumulation reaches 2” in depth.

C. Maintenance and Removal

E&S controls shall be inspected daily during active work and after any rainfall event exceeding 0.5 inch. Damaged or displaced controls shall be repaired immediately and completely prior to the Contractor leaving the site for the day. Upon final stabilization and acceptance, the Contractor shall remove temporary E&S devices and properly dispose of used materials off-site.

PART 3 – EXECUTION

3.1 General Requirements

All dredging, dewatering, and disposal operations shall be performed safely, efficiently, and in full compliance with this Specification, the Contract Drawings, permits, and the Contractor’s approved Dredging Plan. The Contractor shall coordinate continuously with the Engineer and Owner and maintain compliance with all environmental and safety regulations throughout construction.

3.2 Site Preparation

Prior to commencing dredging, the Contractor shall:

1. Verify access, water levels, and site conditions.

2. Install all required erosion and sediment control measures.

3. Establish upland containment and dewatering areas.

4. Set and verify survey control points and benchmarks.

All preparatory work shall be approved by the Engineer prior to mobilization of dredging equipment.

3.3 Environmental and Erosion Control

The Contractor shall maintain all erosion and sediment control measures per the approved plan and Maryland Standards. Turbidity curtains shall be deployed as required to isolate work zones and protect adjacent wetlands.

1. Inspect and maintain all controls daily and after rainfall events.

2. Repair damaged barriers immediately and remove sediment buildup when it reaches 2” in depth.

3. Prevent discharge of dredged water or slurry directly into surface waters without prior treatment.

4. Immediately notify the Engineer and MDE if any inadvertent disturbance to wetlands occurs and implement corrective actions as directed.

3.4 Wetland Protection and Exclusion Zones

A. General

1. Jurisdictional wetlands and waters of the State have been identified adjacent to the dredging areas as documented in the MDE Wetland

Delineation and Assessment Report (included as an appendix to this

Specification).

2. The approximate boundaries of these wetlands are shown on the Contract

Drawings and shall be clearly marked in the field prior to dredging.

3. The Contractor shall not enter, disturb, or perform any dredging, excavation, staging, or equipment operation within delineated wetland areas unless specifically authorized in writing by the Engineer and the

Maryland Department of the Environment (MDE).

B. Prohibited Activities

1. Equipment storage, fueling, and maintenance activities shall be conducted outside delineated wetlands and in a manner that prevents impacts to adjacent wetlands.

2. No temporary access routes, dewatering areas, or stockpiles shall be placed within wetland boundaries.

3. No alteration of wetland vegetation, soil, or hydrology shall occur except as expressly permitted by MDE.

3.5 Dredging Operations

A. General

The Contractor shall perform all dredging operations within the limits shown on the Contract Drawings and in accordance with the approved Dredging

Operations Plan. Mechanical dredging methods shall be used to remove accumulated sediment while minimizing turbidity, disturbance of the existing reservoir bottom, and impacts to adjacent wetlands, embankments, and existing structures.

The Contractor may utilize any combination of mechanical dredging equipment suitable for completing the Work, provided the proposed equipment and methods are approved by the Engineer and comply with the requirements of this Specification.

B. Dredging Requirements

The Contractor shall remove accumulated sediment from the designated dredging areas to the limits shown on the Contract Drawings. Dredging shall generally continue until the existing firm substrate is encountered or the design dredging limits have been achieved.

The Contractor shall perform dredging in a controlled and systematic manner to maintain stable working conditions and minimize the suspension of sediment within the water column.

At a minimum, the Contractor shall comply with the following requirements:

1. Perform dredging only within the approved limits shown on the Contract

Drawings.

2. Avoid over-dredging or unnecessary disturbance of the native reservoir bottom.

3. Avoid disturbance to Wheatley Dam, the spillway structures, shoreline stabilization features, wetlands, or other existing improvements.

4. Generally avoid any and all park facilities.

5. Remove incidental debris encountered within the dredging limits unless otherwise directed by the Engineer.

6. Coordinate dredging operations with the available capacity of the temporary shoreline dewatering and staging areas to prevent interruptions in material handling.

7. Suspend dredging operations during conditions that create unsafe working conditions or result in unacceptable environmental impacts, as determined by the Owner or Engineer.

C. Dredging Sequence

Unless otherwise approved by the Engineer, dredging operations shall generally progress in a logical sequence that minimizes equipment movement, turbidity, and disturbance of previously completed work. The Contractor may modify the proposed dredging sequence as necessary to accommodate field conditions, provided the revised sequence does not adversely affect environmental protection measures, dewatering operations, or overall project progress.

D. Material Handling

Dredged sediment shall be handled in a controlled manner to minimize the loss of material and unnecessary entrainment of water. Sediment shall be transferred directly to the temporary shoreline dewatering and staging areas or to intermediate transport equipment approved by the Engineer.

The Contractor shall avoid unnecessary handling or rehandling of dredged material and shall coordinate dredging operations with hauling and dewatering activities to maintain an efficient and continuous operation.

E. Equipment Operation

All dredging equipment shall be maintained in good operating condition and operated in a manner that minimizes turbidity, protects existing facilities, and prevents release of fuel, hydraulic fluid, or other contaminants.

Equipment shall not be operated in a manner that causes unnecessary damage to the reservoir bottom outside the designated dredging limits or results in excessive disturbance to adjacent environmental resources.

F. Completion of Dredging

Upon completion of dredging activities within each work area, the Contractor shall remove all incidental debris generated by the Work and leave the dredged area in the condition shown on the Contract Drawings. Areas determined by the

Engineer to contain excessive over-dredging, insufficient sediment removal, or unacceptable disturbance resulting from the Contractor's operations shall be corrected by the Contractor at no additional cost to the Owner.

3.6 Temporary Dewatering Operations

A. General

The Contractor shall conduct all temporary dewatering operations within the designated shoreline dewatering and staging areas shown on the Contract

Drawings and in accordance with the approved Dredging Operations Plan.

Temporary dewatering operations shall be coordinated with dredging, hauling, and sediment placement activities to maintain a continuous and efficient workflow throughout the project.

The Contractor shall be responsible for managing dredging production, temporary storage, and hauling operations so that the available capacity of the designated dewatering areas is not exceeded.

B. Placement of Dredged Sediment

Dredged sediment shall be placed within the temporary dewatering areas in a controlled manner that promotes gravity drainage and maintains safe working conditions. Sediment shall be spread, graded, turned, or otherwise managed as necessary to facilitate dewatering and prepare the material for loading into haul trucks.

The Contractor shall not place sediment outside the approved limits of the temporary dewatering areas without prior written approval from the Owner.

C. Dewatering Operations

The Contractor shall manage sediment within the temporary dewatering areas to achieve the dewatering requirements specified in Section 2.3 prior to loading and transport.

The Contractor shall continuously evaluate field conditions and adjust dredging production, placement methods, lift thicknesses, or sediment handling procedures as necessary to achieve the required degree of dewatering.

Sediment shall not be transported from the temporary dewatering areas until the minimum dewatering criteria established in Section 2.3 have been satisfied.

D. Water Management

The Contractor shall maintain positive drainage throughout the temporary dewatering areas and prevent the uncontrolled discharge of sediment-laden water.

Runoff and return water generated during dewatering operations shall remain within the approved erosion and sediment control measures provided for the project. The Contractor shall routinely inspect the dewatering areas and immediately correct any erosion, ponding, sediment migration, or damage to erosion and sediment control measures.

E. Maintenance of Temporary Dewatering Areas

Throughout the project, the Contractor shall maintain the temporary dewatering areas in a safe, orderly, and functional condition. Temporary haul routes, working surfaces, and loading areas shall be maintained to safely accommodate construction equipment under anticipated operating conditions.

Any rutting, unstable working surfaces, erosion, or damage resulting from the

Contractor's operations shall be repaired as necessary to maintain safe and efficient operations at no additional cost to the Owner.

F. Completion of Dewatering Operations

Upon completion of dredging and hauling activities, the Contractor shall remove all remaining sediment from the temporary dewatering areas and restore the areas in accordance with the Contract Drawings.

The Contractor shall remove temporary stockpiles, repair disturbed areas, restore grades, stabilize exposed soils, and leave the dewatering areas in a clean and serviceable condition to the satisfaction of the Owner and Engineer.

Photographic evidence should be provided during the close-out phase of the

Work to confirm that temporary dewatering locations have been restored to the satisfaction of the Owner.

3.7 Sediment Hauling and Placement Operations

A. General

The Contractor shall transport all dredged sediment from the temporary shoreline dewatering and staging areas to the County-Designated Sediment

Placement Area in accordance with the approved Dredging Operations Plan.

The Contractor shall be responsible for providing sufficient hauling and placement capacity to support the planned dredging operations and prevent unnecessary interruptions to the Work.

B. Truck Loading

Dredged sediment shall not be loaded for transport until the minimum dewatering requirements specified in Section 2.3 have been satisfied.

Each haul truck shall have a documented struck capacity, certified box volume, or designated fill line established prior to the commencement of production hauling and approved by the Owner.

The county will have personnel on site to confirm the fill level, quantity, and load counts of the trucks.

The Contractor shall load each truck in a consistent manner to the established capacity or fill line unless otherwise approved by the Owner. Partial loads shall be identified in the daily hauling logs.

The Contractor shall prevent overloading of haul vehicles and shall remove any loose material from the exterior of haul vehicles prior to leaving the temporary dewatering area.

C. Hauling Operations

The Contractor shall transport dredged sediment using vehicles suitable for hauling partially dewatered material.

Haul vehicles shall be maintained in a manner that prevents the loss of sediment, excessive tracking, or leakage during transport. The Contractor shall comply with all applicable traffic laws, approved haul routes, posted weight restrictions, and site access requirements.

Sediment deposited on roadways, access drives, or other traveled surfaces as a result of hauling operations shall be removed promptly. Any damage to existing roadways, drainage facilities, utilities, or other improvements resulting from hauling operations shall be repaired by the Contractor at no additional cost to the Owner.

D. Sediment Placement

The Contractor shall place dredged sediment within the County-Designated

Sediment Placement Area in accordance with Section 2.4 of this Specification.

Sediment shall be unloaded, spread, and graded in a controlled manner to maintain a stable working surface and facilitate continued placement operations. Placement shall proceed in uniform lifts and shall not exceed the maximum lift thickness, stockpile height, or side slopes specified in Section 2.4.

The Contractor shall maintain positive drainage throughout the placement area and shall prevent prolonged ponding, erosion, or sediment migration resulting from placement operations.

E. Maintenance During Placement

Throughout placement operations, the Contractor shall maintain the County -

Designated Sediment Placement Area in a safe, orderly, and functional condition.

Sediment shall be periodically graded or reshaped as necessary to maintain stable slopes, positive drainage, and safe equipment access. The Contractor shall inspect erosion and sediment control measures regularly and promptly repair any deficiencies resulting from placement operations.

F. Completion of Hauling and Placement Operations

Upon completion of sediment hauling and placement, the Contractor shall leave the County-Designated Sediment Placement Area in the configuration approved by the Owner.

The Contractor shall remove temporary equipment, clean haul routes and loading areas, stabilize disturbed soils, and restore any areas impacted by hauling or placement activities in accordance with the Contract Documents.

3.8 Measurement, Documentation, and Quantity Verification

A. General

The Contractor shall maintain complete and accurate records of dredging, hauling, and sediment placement activities throughout the duration of the Work.

Documentation shall be sufficient to verify the quantity of dredged sediment transported to the County-Designated Sediment Placement Area and to demonstrate compliance with the Contract Documents.

Measurement for payment shall be based on the verified volume of dredged sediment delivered to the County-Designated Sediment Placement Area.

B. Truck Volume Verification

Prior to commencement of production hauling, the Contractor shall establish the carrying capacity of each haul vehicle used for sediment transport.

The carrying capacity of each truck shall be established by one of the following methods, subject to approval by the Owner:

1. Certified struck box volume provided by the truck manufacturer.

2. Field measurement of the truck box dimensions to establish a certified hauling volume.

3. A designated fill line approved by the Owner corresponding to a known hauling volume.

The approved hauling volume for each truck shall remain consistent throughout the project unless otherwise approved by the Owner.

C. Daily Hauling Documentation

The Contractor shall maintain daily hauling logs documenting all sediment transported from the temporary shoreline dewatering areas to the County -

Designated Sediment Placement Area.

At a minimum, each daily hauling log shall include:

1. Date.

2. Truck identification number.

3. Driver (optional, if requested by the Owner).

4. Number of loads hauled.

5. Estimated volume of each load.

6. Identification of any partial loads.

7. General placement location, if requested by the Owner.

8. Comments regarding unusual field conditions or operational interruptions.

Daily hauling logs shall be submitted to the Owner to be cross-referenced with the Owner’s own logs.

D. Quantity Verification

The Owner reserves the right to verify hauled quantities through periodic field observation, inspection of haul vehicles, photographic documentation, review of hauling logs, or other reasonable means.

The Contractor shall provide reasonable access to haul vehicles, loading operations, and placement activities for the purpose of quantity verification.

If significant discrepancies are identified between the approved hauling volumes and actual hauling practices, the Owner may require the Contractor to revise the quantity documentation procedures or re-establish the certified hauling volume for affected vehicles.

E. Final Quantity Summary

Upon completion of the Work, the Contractor shall submit a Final Quantity

Summary documenting the total verified volume of dredged sediment transported to the County-Designated Sediment Placement Area.

The Final Quantity Summary shall include:

Total number of truckloads.

Total verified hauled volume.

Summary of any approved partial-load adjustments.

Copies of the daily hauling logs.

The Engineer will review the submitted documentation and determine the final measured quantity for payment in accordance with this Specification.

3.9 Site Restoration and Cleanup

Upon completion of dredging and hauling:

1. Remove temporary containment and E&S measures.

2. Regrade disturbed areas to pre-work contours.

3. Apply topsoil and seed per the Maryland E&S Manual.

4. Repair any rutting or damage to access routes, park surfaces, or vegetation.

5. Remove all temporary facilities, debris, and unused materials from the site.

Pre- and post-construction photographs shall document restoration. Final payment will not be made until the Owner verifies that all restoration, stabilization, and documentation requirements have been met.

END OF SECTION 02480