Environmental Management

March 2017

The Watershed Management Branch, Prince William County Public Works Department, Environmental Services Division contracted with Versar, Inc. to conduct a watershed study in the five northernmost subsheds of the Neabsco Creek watershed. The purpose of the study was to assess the condition of existing stormwater management facilities and streams. This information will be used to identify Capital Improvement Projects (CIP). The intent of these projects is to improve water quality for the residents of the County.

In addition to identifying existing problems, the study also identified new opportunities through reforestation and land conversion projects. By restoring natural functions to land that has been affected by development, the County can use innovative strategies to help achieve the goal of improving local waterways as well as help in the restoration of the Chesapeake Bay.

View the full report on the Neabsco Creek Watershed Final Study along with supporting documents:

Appendix A - SW Facility Conversion Fact Sheets

Appendix B - New BMP Fact Sheets.pdf

Appendix C - Outfall Stabilization Fact Sheets.pdf

Appendix D - Reforestation Fact Sheets.pdf

Appendix E - Stream Restoration Fact Sheets.pdf

March 2014

Prince William County Public Works, Watershed Management Branch of the Environmental Services Division, conducted a study of four subwatersheds (“subsheds”) within the portion of the Occoquan Watershed in Prince William County. The purpose of this subshed study was to provide guidance for Capital Improvement Projects (CIP) by using a combination of GIS data and field assessment techniques to prioritize and plan how impaired streams, Stormwater Management and Best Management Practice (SWM/BMP) Facilities, and other infrastructure can be improved and/or restored within the 4 selected subsheds.

The 4 subsheds of interest total over 3,100 acres, which is approximately 10 percent of the portion of the Occoquan Watershed in Prince William County. Initial GIS desktop screening provided helpful overall watershed information and is summarized in 13 watershed categorization maps. All four subsheds are predominately developed with a range in impervious cover from 37 to 72 percent, with Subshed 450 having the most impervious surfaces. Contiguous wetlands and streams do exist and many are protected with a forested buffer. Adjacent to these subsheds, Occoquan River is listed as an impaired 303(d) water for low dissolved oxygen, fecal coliform, and PCBs. In 2012, Hooes Run was added to the list of impaired waters for exceeding fecal coliform bacterium criteria for recreation water usage. Overall, the watershed characterization summary and maps show that while some surface waters and environmental resources within the subsheds are being protected, more efforts are required to protect the Occoquan River and the Chesapeake Bay.

View the full report for the Occoquan Watershed Final Study with supporting documents:

Appendix A Location Map

Appendix B Watershed Characteristics

Appendix C Facility Recon Map and Summary

Appendix D Facility Site Photos

Appendix E Stream Recon Map

Appendix F Stream Assessment Photos

Appendix G Exposed Utilities

Appendix H Selected Conceptual Plans Map

Appendix I Facility Conceptual Plans

Appendix J Part 1 Stream Conceptual Plans

Appendix J Part 2 Stream Conceptual Plans

Appendix K Funding Options

• Appendix A
• Appendix B
• Appendix C
• Appendix D
• Appendix E
• Appendix F
• Appendix G

• Quantico Watershed Study Appendix 1
• Quantico Watershed Study Appendix 2
• Quantico Watershed Study Appendix 3
• Quantico Watershed Study Appendix 4
• Quantico Watershed Study Appendix 5

• Sediment Forebay Report Appendix A
• Sediment Forebay Study Appendix B
• Sediment Forebay Study Appendix C
• Sediment Forebay Appendix D
• Sediment Forebay Report Appendix E
• Sediment Forebay Report Appendix F
• Sediment Forebay Report Apps
• Sediment Forebay Report Options

LAKE MONTCLAIR SEDIMENTATION CONTROL FEASABILITY STUDY

July 2008

WHITMAN REQUARDT & ASSOCIATES LLP

Prince William County Watershed Management Branch engaged Whitman Requardt & Associates to evaluate erosion and sediment transport in the upper reaches of Powells Creek above Lake Montclair. The purpose of the study was to determine the feasibility of reducing the sediment load and deposition to Lake Montclair.

The final report presents the findings of the study and provides information about the condition of the upper stream reaches sediment transport mechanisms and three (3) conceptual designs and locations for a sediment trapping forebay in the vicinity of the upper end of Lake Montclair.

View the full report for the Lake Montclair Sedimentation Control Study.

POWELLS CREEK WATERSHED MANAGEMENT PLAN

June 2008

MICHAEL BAKER CORPORATION

Prince William County Watershed Management Branch tasked Michael Baker Corporation with examining the entire Powells Creek Watershed to build on previous watershed assessment studies; evaluate current conditions in the watershed; and to present the findings in a series of strategic and focused conceptual project plans to be used to budget future Capital Improvement Project (CIP) funds. Additional objectives were to provide mitigation for ongoing County projects and to measure progress toward protecting the watershed.

This report presents general recommendations applicable to the full watershed and suggests nineteen (19) concepts for potential CIP projects at an estimated cost of approximately $7500000. The concepts presented include: stream restoration stream enhancement storm water pond retrofits culvert retrofits and Low Impact Development (LID) projects.

View the full report on the Powells Creek Watershed Management Plan along with supporting documents:

• Powells Creek Watershed Plan Appendix A
• Powells Creek Watershed Plan Appendix B.

BULL RUN WATERSHED STUDY

March 2010

WHITMAN REQUARDT & ASSOCIATES LLP

The Watershed Management Branch Prince William County Public Works Department Environmental Services Division and Whitman Requardt & Associates (WR&A) recently completed a study of portions of the Bull Run Watershed (Linden Yorkshire and Buckhall areas). The purpose of the study was to assess current stream conditions and to examine existing storm water management facilities to identify and prioritize problem areas. The results will be used to recognize opportunities for future Capital Improvement Projects.

This report presents the findings of the study, makes recommendations and provides planning cost estimates totaling almost $1,400,000 for the nineteen conceptual projects identified as a result of the study.

View the full report for the Bull Run Watershed Final Study with the following documents:

• Bull Run Watershed Study Maps
• Appendices for the Bull Run Watershed Study

FARM CREEK AND MARUMSCO CREEK WATERSHED MANAGEMENT PLAN

December 2009

PARSONS BRINCKERHOFF

The Watershed Management Branch Prince William County Public Works Department Environmental Services Division and Parsons Brinckerhoff (PB) recently completed a study of the Farm Creek and Marumsco Creek Watersheds in eastern Prince William County. The purpose of the study was to assess current stream conditions, to examine existing storm water management facilities in order to identify and prioritize problem areas and to review historical flooding issues within the watershed(s). The results will be used to recognize opportunities for future Capital Improvement Projects.

This report presents the findings of the study, makes general watershed recommendations and provides planning cost estimates totaling almost $6,000,000 for twenty-nine conceptual projects identified as a result of the study.

View the full report for the Farm Creek and Marumsco Creek Watershed Study with supporting documents:

• Appendix A part 1
• Appendix A part 2
• Appendix B
• Appendix C
• Appendix D