Mary Bowerman Trail Accessibility Improvements

Mary Bowerman Trail Accessibility Improvements

Improve severely degraded, failing, non-accessible sections and parking within the original trail prism of the Mary Bowerman Trail at Mount Diablo State Park to create .2 miles of Americans with Disabilities Act (ADA) complaint trail in proximity to the summit, protect resources and increase visitor safety. Parking: Excavate up to 8" to place 18" of aggregate base with 5" of concrete on top to construct a new concrete van accessible parking stall, aisle and transition area within the existing paved area at the current trailhead, and excavate up to 36" for concrete post footings to install new traffic sign on Summit Road. Restore some surrounding soil to natural conditions, re-contour to drain away from paved surfaces and add approximately 4" mulch cover. Install approximately 24" cobble rock adjacent to parking stall to drain away from paved area. Trailhead: Excavate up to 36" to install concrete post footings for new trail head signage with an approximately 9'x9' level concrete landing; place 6"-8" rock over engineered fabric for slop protection around existing vegetation. Trail: Excavate up to 6" to remove existing asphalt; retaining wall, drain inlet and approximately 24" of scree behind retaining wall. Excavate up to 24" to place 6" of aggregate base with 5" of concrete on top treated with oxidizer to construct a 4' wide concrete trail with a 4'x6' concrete curb, up to 65" deep to install 4"x60" steel hollow-core H-beam with 4"x12"x10' redwoods planks to construct retaining wall backfilled with 4" drain rock at deck abutments. Install approximately 3' wide x 20' long rock-lined swale up slope of the trail. Overlook Deck: Place new blocking between existing joists to alter the decking configuration to run perpendicular to the path of travel, secure 2"x6" redwood planks to replace decking and 6" redwoods curbing on upslope side, install 4"x6' redwood post, 2"x4" redwood rails at top, middle, bottom and 4"x6' redwood brace to construct new 42" tall safety railing with safety mesh screening along the face of the deck. Replace benches and timber curbing. Trail Terminus: Excavate up to 24' to place 6" of aggregate base with 5" of concrete on top treated with oxidizer to construct a concrete overlook with a 4"x4" concrete curb within limits of existing paved surface, excavate up to 30" for concrete footings to install 2 new hi/lo spotting scopes, excavate up to 36" for concrete post footings to install a new interpretive panel and reinstall a salvaged interpretive panel. To excavate up to 45" to place 6" compacted aggregate base with approximately 36" of concrete on top to construct a concrete retaining wall treated with oxidizer and a 6" concrete curb on the upslope side. Construction: Install protective fencing around construction areas and stage equipment and materials in the existing dirt parking area across Summit Road.

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