Arcadis Design and Consultancy presented a field assessment plan re: Lake Accotink dredging at a public meeting in December 2020. They will conduct aerial and hydrographic surveys; sediment and geotechnical investigations; and perform soil borings and groundwater gauging.

1. Field Assessment Plan
14 December 20201
 Surveys
 Sediment Investigation
 Geotechnical Investigation
 Desktop Studies

2. © Arcadis 2020
Surveys
14 December 2020 2
Image courtesy WSSI Image: https://www.auav.com.au/articles/drone-data-vs-lidar/Image courtesy Waterways
Image courtesy Waterways
Investigation Purpose Activities
Aerial Survey Generate topography data to support
design of potential support areas
LiDAR data and aerial photography
from fixed-wing plane
Hydrographic Survey Map bathymetry for dredging design
and identify potential obstacles to
dredging
Single beam bathymetry, side scan
sonar, and magnetometer survey

3. © Arcadis 2020
Sediment Investigation
14 December 2020 3
 Purpose: Determine
sediment physical
properties for dredging,
dewatering, and disposal
 Activities:
 Sediment core collection
 Laboratory testing for
physical parameters
 Treatability testing
Images provided by Arcadis

4. © Arcadis 2020
Sediment
Investigation
14 December 2020 4
Sanitary
Sewer

5. © Arcadis 2020
Geotechnical Investigation
14 December 2020 5
 Purpose: Provide the design
basis for earthwork and
structural components
 Activities:
 Soil borings
 Groundwater gauging
 Laboratory testing for physical
parameters

6. © Arcadis 2020
Desktop Evaluations
Wetland Delineation Vegetative Community Mapping
14 December 2020 6
Source: Portion of Environmental Constraints Map in Lake Accotink Management Plan – Additional Study (WSSI 2018)

7. Selection Criteria
14 December 20207
• Dredging
• Pipeline / Material Conveyance
• Dredge Material Processing

8. © Arcadis 2020
Dredging Operations
Category Proposed Selection Criteria
Park Management Consistency with Long-Term Park Vision
Community
Recreational Use Restrictions During Construction
Community Considerations During Construction
Environment
Environmental Considerations
Floodplain Impacts
Compatibility with Water Quality Requirements
Sustainability
Construction
Accessibility to Work Areas
Constructability
Schedule
Cost
14 December 2020 8

9. © Arcadis 2020
Pipeline / Material Conveyance
14 December 2020 9
Category Proposed Selection Criteria
Park Management Consistency with Long-Term Park Vision
Community
Recreational Use Restrictions During Construction
Community Considerations During Construction
Environment
Environmental Considerations
Floodplain Impacts
Sustainability
Construction
Construction/Maintenance Accessibility and Security
Flexibility/Compatibility with Various Equipment
Long-Term Infrastructure Maintenance
Constructability
Schedule
Cost

10. © Arcadis 2020
Dredged Material Processing
14 December 2020 10
Category Proposed Selection Criteria
Park Management
Consistency with Long-Term Park Vision
Compatibility with Long-Term Operation and
Maintenance
Community
Recreational Use Restrictions During Construction
Community Considerations During Construction
Environment
Environmental Considerations
Floodplain Impacts
Sustainability
Construction
Available Area and Accessibility
Site Preparation Requirements
Efficient Water Return
Flexibility/Compatibility with Various Equipment
Constructability
Schedule
Cost