Webberville Solar Project

SITE OVERVIEW

The Project site is generally flat and slopes in a southeasterly direction. The site conveys stormwater runoff from several watersheds located on and adjacent to the site, as well as overflow from a larger stream located to the northwest. Stormwater detention areas are installed to attenuate peak flows to limit discharges from the site to pre-developed conditions. The inverter pads have a minimum elevation along with 100-year water surface elevations (WSELs) based on the floodplain analysis cross-sections. Panel heights also considered the 100-year WSELs. The topsoil consists primarily of Smithville-Ships-Bergstrom sandy, silty clay loam. Soil borings presented in the geotechnical report divides the Project site into two sections – the southwest section can be generalized as 4 to 7 feet of fat clays and lean clays with high plasticity underlain by low to medium-plasticity lean clays and sands; the northeast section can be generalized as over 10 feet of fat clays with high plasticity underlain by lean clays and sands. Existing grade was maintained with slight earthwork for the installation of roads, maintenance facilities and foundation construction.

Most pre-and post-construction stormwater flows to the southeasterly site boundary. The installation of solar panels allows precipitation to continue to fall to the ground and the ground will remain in its natural condition. The construction of access roads modified the overland flow slightly, but the roads were not paved, and the gravel base allows some infiltration. Detention facilities were installed to limit the post-development outflow rate to pre-development conditions. Soil erosion and sediment control (SESC) were established along the entire site perimeter. Rock check dams were placed in areas where stormwater flow velocities needed to be reduced. A stabilized construction entrance was provided at the FM 969 approach. Continuous silt fence was placed around the project perimeter. The restorative vegetation consists of low-growing ( < 3 ft) grasses that should not cause shading onto the solar array.