Planning, Design, and Envision Verification of Crosby-Eastgate Wetlands Mitigation Bank, Harris County Flood Control District, Harris County, Precinct 2, Harris County, Texas


Harris County owns approximately 240 acres of undeveloped, forested, and heavily vegetated land adjacent to Cedar Bayou located east of Crosby-Eastgate Road and north of Felscher Road in Harris County Precinct 2.  As a result of an anticipated increase in unavoidable impacts to waters of the United States arising from Harris County mobility improvement projects and HCFCD channel improvement and detention projects, Harris County Precinct 2 has requested that Harris County Flood Control District (HCFCD) move to develop a wetlands mitigation bank on the subject property.  The development of the bank will provide compensatory mitigation credits that can be used to offset the anticipated unavoidable losses in the area.

HCFCD retained R. G. Miller Engineers, Inc. (RGME) to provide environmental services, Envision Sustainability Professional services, and civil engineering design services to support the creation of a new Mitigation Banking Site along Cedar Bayou.  To obtain permission from the Galveston District (SWG) of the U.S. Army Corps of Engineers (USACE) and the Interagency Review Team (IRT) and to create a new mitigation bank, a number of technical studies have been conducted and formal reports submitted for USACE and IRT review.

Thus far RGME has planned and laid out temporary access trail locations and cut them using forestry mulching equipment; oversaw a geotechnical investigation of all soils and conducted site specific field measurements of infiltration using a double-ring infiltrometer; oversaw a Phase I environmental site assessment; completed all field work associated with a cultural resources survey; spot-checked field elevations to adjust Light Distance and Ranging (LiDAR) based topography; developed a detailed water balance model and conceptual design to estimate the area and duration of site inundation achievable with site modifications such as berms and outfall structures; prepared draft mitigation banking rule Prospectus; determined baseline functional capacity indices and units for existing wetland areas and estimated functional capacity indices and units achievable after increased inundation;  and prepared and submitted a draft Mitigation Banking Instrument with conceptual mitigation plans.

RGME civil engineers oversaw a geotechnical investigation, survey, and subsurface utility engineering services to support bank design. RGME is currently using Envision to design the weir structures, access road, perimeter fencing, and other site alterations. The Envision Sustainable Infrastructure Framework is a rating system that helps owners maximize the social, economic, and environmental outcomes on public infrastructure projects.  RGME is preparing detailed narratives and supporting documentation to explain the planning and design steps and decisions used to meet credit requirements and to support the application.  This is the first HCFCD project to pursue verification under the Envision Sustainable Infrastructure Framework.

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