PG&E Boardwalk Access Program - Petaluma River Projects (Notification of Lake or Streambed Alteration, No. EPIMS-MAN-53257-R3)

PG&E Boardwalk Access Program - Petaluma River Projects (Notification of Lake or Streambed Alteration, No. EPIMS-MAN-53257-R3)

The California Department of Fish and Wildlife has executed Lake and Streambed Alteration Agreement EPIMS Notification No. EPIMS-MAN-53257-R3, pursuant to Section 1602 of the Fish and Game Code, to Pacific Gas and Electric Company. The Project is limited to constructing two new boardwalk structures, and demolition of one existing boardwalk structure. The existing boardwalk at Site 1, Location 1 will be demolished in conjunction with the construction of the new boardwalk at Site 1, Location 2. Construction of a new boardwalk will occur at Site 2, Location 3. The boardwalk projects require temporary barge staging areas for equipment that will remain for the duration of the Project. The barges measure approximately 100 by 100 feet and will be anchored by approximately 24-inch diameter support posts that will be embedded into the mud by a built-in pile guide consisting of a steel cylinder spud well. The spud well uses a hydraulic motor that lowers the posts (i.e., spud piles) into the mud until secure, and then the barge is tied to the spud well and can float in place with the tides. No vibratory or impact hammer is used for spud pile placement or boardwalk post placement, therefore no pile driving will take place. Once construction reliant upon the barge is complete, the barge and the support posts will be removed using the built-in pile guide and moved to another part of the Project by boat or removed from the water. At Site 1, Locations 1 and 2, 366 linear feet (1,099 square feet) of new boardwalk construction will occur) and 1,358 linear feet (4,073 square feet) of existing boardwalk demolition will occur. At Site 2, Location 3, 562 linear feet (1,099 square feet) of new boardwalk construction will occur. All work will occur within an approximately 9-foot-wide temporary work area, consisting of a 3-foot-wide footpath on either side of the boardwalks, as well as the area under the boardwalk. Vegetation removal and/or clearing may be required within work areas to provide access to the boardwalk alignments. Vegetation removal will be done by hand and/or by using hand tools in marsh vegetation. Floating platforms may be used in work areas that lack vegetation and are inundated with water (i.e., tidal mudflats and open water). The floating platforms are approximately 12 feet by 28 feet. Once placed in the water, floating platforms will be tied to the existing or new boardwalk and remain in the work area until boardwalk construction activities are complete. The existing boardwalk that will be demolished at Site 1, Location 1 consists of untreated wood with a three-plank-wide (36-inch) walkway. New boardwalks will be composed of composite plastic and fiberglass material with three-plank-wide walkways and double handrails (i.e., a handrail on each side of the boardwalk). New boardwalks will be installed approximately 12 to 24 inches higher than existing boardwalks to reach the top of tower foundations or to accommodate anticipated sea level rise over the expected 50-year lifespan of the materials. Boards will be spaced 0.5 inch apart to allow light penetration. All construction will be done with hand tools and no heavy equipment will be used. Materials for the new boardwalks include plastic composite lumber, untreated wood, galvanized steel nails, bolts, washers, and nuts. In addition, galvanized steel mesh gates will be replaced and installed, as needed, to prevent unauthorized public access to boardwalks for public safety and security. Construction materials and equipment will be moved from barges to the boardwalk alignment and then carried by hand or with the use of handcarts. Boardwalks will be supported by 4-inch by 4-inch vertical plastic lumber posts spaced approximately 10 feet apart. The support posts will be manually pushed into the ground with a hickey bar, therefore there will be no spoils. A 3-foot-wide work area is required on either side of the posts for installation. The boardwalk framework (e.g., headers and cross-braces) will be secured to the support posts using bolts, washers, and nuts. Three replacement boardwalk planks, each 1 foot wide, will be secured to the headers using bolts, washers, and nuts. A double handrail will be secured to the headers using bolts, washers, and nuts. Boardwalk demolition will be accomplished by using circular saws and chainsaws to cut apart and remove portions of the existing boardwalk. Demolition will include aboveground materials including posts, cross bracing, kickers, caps, planks, and any existing railing. Lumber posts will be cut down to as close to the mudline as possible. Demolished materials will be removed from the work area for offsite disposal. The Project will result in approximately 37,790 square feet (0.868 acres) of temporary impacts of which 17,790 square feet (0.41 acres) is from boardwalk demolition and construction and associated work areas, and 20,000 square feet is from barge work. The Project will result in approximately 2,785 square feet (0.064 acres) of permanent impacts associated with building the new access boardwalks. The Project will result in 4,074 square feet (0.094 acres) of restored salt marsh habitat associated with removing access boardwalk for a net permanent salt marsh habitat increase of approximately 1,289 square feet (0.029 acres). No trees will be removed by the Project and no piles of removed fill will be stockpiled.

Marin

San Francisco Bay Area

Marin