Maryland State Highway Administration – Environmental Programs Division
- Wetland Creation and Enhancement
- Stream Restoration Design
- Environmental Permitting
- Natural Resources Inventory/Wetland and Forest Stand Delineations
- Stormwater Management
- Water Quality Improvements
- Invasive Species Removal and Management
Coastal Resources, Inc. (CRI) provided site environmental assessment and design services for the Maryland State Highway Administration’s (SHA) Intercounty Connector (ICC) Compensatory Mitigation (CM) site PB-1 (contract PB-A). CRI provided non-tidal wetland mitigation and stream restoration design services, Clean Water Act (CWA) permitting, natural resources evaluation and reports, wetland delineations, large tree surveys, forest stand delineations, Forest Conservation Act (FCA) compliance and permitting, hydrologic and hydraulic analyses, stream assessment and monitoring. CRI also provided designated specialist services during construction.
The PB-1 project is a wetland mitigation, reforestation, and stream restoration site located in Montgomery County, Maryland within the Upper Paint Branch Special Protection Area. The mitigation site is a 60.4 acre parcel owned by SHA, but is also connected to a portion of two parcels (100.9 acres) owned by the Maryland-National Capital Park and Planning Commission (M-NCPPC). The PB-1 site contains a large portion of the headwaters of the Right Fork Tributary of Paint Branch, a Use III trout stream. The site has historically been associated with agricultural land uses, but more recently, the site was being developed by a previous contractor for residential housing until the property was purchased by SHA. Portions of the site had rough grading for residential roadways, and contained elements of sediment control and stormwater management infrastructure (i.e., stormwater pipes and detention ponds) from the previous developer.
The restoration concept for PB-1 included grading and planting to create forested and scrub-shrub wetlands, invasive species removal followed by reforestation with native species, and the removal or conversion of all ponds to reduce thermal impacts to the Paint Branch. In addition to the stated restoration objectives and concepts, the design team recognized the importance of this site with regard to the Paint Branch Special Protection Area (SPA), which is home to a naturally reproducing population of brown trout. The design team’s approach for restoration of the site focused on the importance of this coldwater fishery, and site concepts were based on the analysis of existing and collected data to promote positive effects on physical conditions (e.g. groundwater recharge/coldwater input, reduction in fine sediment inputs), which are known to sustain biological conditions for brown trout. Additional objectives identified for the PB-1 mitigation site included:
- Prioritizing infiltration practices to supplement groundwater hydrology
- Creating more natural landforms in the footprint of the development area
- Invasive species removal and management of Bradford Pear, Pyrus calleryana and Autumn Olive, Elaeagnus umbellata
- Reducing sediment sources on-site
- Avoiding and minimizing loss of native trees existing on-site
The innovative restoration design for the PB-1 site works around the stormwater piping installed for the housing development to create a diverse mosaic of habitats. Low spots in the topography, originally graded to direct runoff from the housing development towards storm drains and ponds, are designed for creation of scrub-shrub and forested wetlands. Cutoff trenches designed to impede groundwater movement are strategically located to increase groundwater retention times and elevate the groundwater table to provide hydrology for creation of forested wetlands adjacent to existing wetland resources. Stormwater runoff infiltration devices were installed to capture overland flow and direct it towards groundwater recharge. Stream restoration design included removal of two failed stream culverts and one collapsed bridge from the streams and replacement with open channel riffle grade control features. Degraded and incising micro-channels located along the floodplain were stabilized to prevent draining of existing riparian wetlands. SWM retrofit was also included in the project design to provide quantity and quality control of surface runoff from the site. Invasive species were removed from the majority of the property, and open areas were reforested with a mix of native wetland, riparian, and upland species. In total, the PB-1 project design provided 10.3 acres of created emergent, shrub, and forested wetlands, and 45.1 acres of riparian and upland reforestation.
CRI prepared the Joint Permit Application and impact plates, Preliminary Investigation (30% design), Semi Final (60% design), Final (90% design), and PS&E (100% design) submittals, and erosion and sediment control plans. CRI also presented the design strategy to review agencies at Interagency Workgroup (IAWG) and Brown Trout Workgroup (BTWG) meetings, acquired all environmental permits including erosion and sediment control permits, and developed a post-construction monitoring plan for the site. Final Design Plans, Specifications, and Estimate for the PB-1 project were completed in 2011, and construction was completed in 2012. CRI provided designated specialist services during construction and prepared a monitoring plan.