LZ03 Sanitary System Rehabilitation Project

Coastal Resources, Inc. (CRI) conducted a supplemental Waters of the U.S. (WOTUS) delineation and tree survey, and conducted a targeted rare, threatened, and endangered (RTE) plant survey for the LZ03 wastewater pipeline rehabilitation project in Cabin John, MD, and the District of Columbia.  The project is part of the proposed improvements to the Potomac Interceptor sanitary system, and due to recent changes in the LOD, additional surveys were required to collect additional data. Additional study areas along LZ03A and LZ03B, totaling approximately 1.5 acres, as well as a 10-foot buffer along the Chesapeake & Ohio (C&O) Canal tow path (5 acres) were assessed.  In addition, based on discussions with regulatory agencies, the C&O Canal is considered a regulated waterbody and was thus included as a separate study area to be delineated (approximately 2 miles in length). 

CRI conducted a tree survey within the additional study areas and along the towpath.  The tree survey included all trees greater than or equal to 4 inches diameter at breast height (DBH). All trees were GPS-located using a handheld Trimble GPS unit / Trimble Global Navigation Satellite System (GNSS) receiver. CRI post-processed the data and prepared a shapefile including tree number, common name, scientific name, size, and condition.

CRI also conducted an RTE plant-specific survey within the additional LZ03A and LZ03B study areas to identify any additional populations of the state threatened buttercup scorpionweed (Phacelia covillei). The survey was conducted in the spring of 2021, during the appropriate growth period, by slowly traversing the study area. A total of 43 areas were identified including clusters or scattered individuals of the buttercup scorpionweed.

The two study areas, in addition to two miles of the C&O Canal and its immediate buffer, will be field investigated to identify and survey the boundaries of WOTUS, including wetlands.  Wetlands will be identified in accordance with the Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Atlantic and Gulf Coastal Plain Region, Version 2 (USACE 2010).  Wetland and upland plots will be established for each identified wetland at representative locations throughout the study area to document that the boundary of the wetland was properly determined.  All identified wetland indicators will be recorded on a Wetland Determination Data Form. Delineated WOTUS will be located using a handheld Trimble GPS unit/Trimble GNSS receiver.  All identified WOTUS, including wetlands, will be classified according to A Classification of Wetland and Deep-Water Habitats in the United States (USFWS 1979) and a function and value assessment completed using the New England Method.  A formal functions and values analysis will be conducted for all wetlands greater than ½ acre in size and function and value suitability will be noted for smaller wetland systems using best professional judgement. CRI will provide the team with shapefiles for wetlands, waters, and test plots in addition to field data sheets and site photographs.


Montgomery County, MD and Washington, DC


DC Water

Key Services:

  • Waters of the U.S. Delineation
  • Tree Survey
  • Rare, Threatened, and Endangered Plant Survey