The restoration of wetlands on the former Hamilton Army Airfield is a joint project between the US Army Corps of Engineers, San Francisco District, and the State Coastal Conservancy The Project was authorized by Congress in 1999 under the Corps’ civil works authority. The project involves a total of nearly 2600 acres of land at the Hamilton Airfield and at the adjacent Bel Marin Keys properties.
A word about the names (alphabet soup): During the military base closure process which occured under the Base Realignment and Closure Act (BRAC), the airfield property was referred to as the Hamilton Army Airfield (HAAF). Adjacent to the Airfield, is the North Antenna Field, which was used by the military as a communications facility and which contained a small-arms range, skeet range and several disposal areas. That property is currently being cleaned up by the Army Corps of Engineers under its Formerly Used Defense Sites (FUDS) program. In 1999 our Congress authorized, in the Water Resources Development Act (WRDA), the wetland restoration project as the Hamilton Wetland Restoration Project (HWRP). After the Coastal Conservancy acquired the neighboring farmland, the project was enlarged by an amendment to the original WRDA authorization. The official title for that act was the “Bel Marin Keys Unit V Expansion of the Hamilton Wetland Restoration Project”. We call the larger restoration project the “Hamilton-BMKV project” for short. Some people have suggested that this restoration project be renamed the Novato Baylands, though that would no doubt also require an act of Congress.
The wetland restoration project began in 1994 when the Conservancy met with representatives from the City of Novato and other agencies that were discussing the closure of the Hamilton Army Air Base. In 1996 the Conservancy granted funds to the City to undertake a plan for restoring tidal wetlands to the areas once occupied by the runway and taxi ways. At the same time that the City was engaged in redevelopment of the Base for residential and commercial development, various federal and state environmental agencies were looking more closely at opportunities to restore wetlands using clean dredged sediments. Hamilton Airfield came to the top of the list of potential projects because the land was subsided, which meant that fill was needed to reestablish grades, the site was going through the military closure process, known as Base Realignment and Closure or BRAC, and the site was contiguous with other marshes that support threatened and endangered species.
Public Access: The project includes construction of a segment of the San Francisco Bay Trail. Under the current restoration project, a trail will be constructed along the southern perimeter, extending along the western most edge of the project area and then north to Pacheco Pond. An extension of this trail is planned to run from along the eastern side of Pacheco Pond to Bel Marin Keys Boulevard. More details about the trail can be found under the Public Access tab, above.
Following closure of the Hamilton Army Airbase in 1994 and development of a Reuse Plan by the City of Novato for much of the former military base. the Conservancy assumed the lead in developing a wetland restoration plan for the former Hamilton Army Airfield and adjacent properties. In 1996, Conservancy staff joined with staff from the San Francisco Bay Conservation and Development Commission (BCDC) to address the technical aspects of restoration and to better link the project with the efforts of BCDC in finding ways to restore wetland habitat using dredged sediment. In April 1999, the Conservancy adopted the Hamilton Wetlands Restoration plan and certified the EIR-EIS for the project. The Conservancy entered into agreements with the Army Corps of Engineers to study the feasibility and design of the project; these agreements were entered into in 1998 and 1999, respectively. In 1999, the Congress of the United States authorized the project under the ecosystem restoration authority of the Civil Works program. Subsequently, the project has received federal funding to carry out project design, development and construction.
In 1999, Conservancy also signed an agreement with the Army Base Realignment and Closure (BRAC) program for the transfer of the Airfield parcel as a no-cost, public benefit transfer for wildlife conservation. In January of 2001, the Conservancy purchased the 1600-acre Bel Marin Keys Unit V property for wetland restoration purposes, with the intent of adding it to the existing Hamilton project. The Conservancy accepted title to the Army Airfield parcel under a no-cost, public benefit conveyance and title was transferred on September 30, 2003. A remnant 18-acre portion of the Airfield, owned by the Navy, was later transferred in 2006, under a similar BRAC conveyance. The Army and Navy BRAC programs undertook extensive chemical contaminant investigation and remediation prior to transfer. Contaminant investigations were reviewed and approved by the state Department of Toxic Substances Control, Regional Water Quality Control Board and other state and federal regulatory and resource agencies.
On April 14, 2002, the Conservancy entered into a Project Cooperation Agreement (PCA) with the Army Corps of Engineers for implementation of the Hamilton wetland restoration project. This agreement formally started construction of the project. Under the PCA, the Army will construct the wetland restoration project using suitable dredge material pursuant to federal law and practice. The Conservancy has responsibility to take title to the lands, easements and rights of way necessary to construct the project, and to pay 25% of project costs.
The Conservancy has also worked closely with the Novato Sanitary District (NSD) to relocate a de-chlorination station from the Hamilton project site and is currently examining options for relocation of the NSD outfall pipeline, which runs across the Bel Marin Keys Unit V.
In 2002 and 2003 the he Conservancy and the Corps completed the planning for the addition of BMK property to the project. The SEIR-EIS was completed in April 2003; however, the Corps has delayed the completion of the Record of Decision pursuant to the National Environmental Policy Act pending approval by Congress. The SEIS-SEIR and General Re-evaluation Report was used as the basis for an amendment to WRDA to allow for the expansion of the project on to the BMK portion. in 2007 a WRDA bill was adopted by Congress, allowing for BMKV to be added to the federally-authorized Hamilton Wetland Restoration Project
Bel Marin Keys (BMK) Portion- Project Description:
Restoration of tidal wetlands on the BMK property requires constructing similar features as are proposed for the Hamilton Airfield. To create tidal marsh, site elevations will be brought back up to mean-higher-high water, a point at which marsh vegetation normally thrives. Raising the site elevation involves the placement of soil or sediment fill, natural sedimentation provided by tidal action, or a combination of both. Therefore the focus of the expanded Hamilton project is on the design and construction of earthen structures, flood control levees, dikes and berms and the placement of large volumes of imported fill, mainly sediment that will be pumped ashore from an offloader. The SEIR assessed and disclosed the impacts of constructing the site features, and the changes to the landscape after construction is complete and tidal action is restored to the land.
Minimization of Greenhouse Gas Emissions: Filling of the Hamilton Airfield was accomplished using an electrically-driven offloading system, which minimized localized diesel emissions. Much of the sediments that were offloaded at the site came from dredging projects that would otherwise have been disposed of at the Deep Ocean Disposal Site (DODS). The ocean disposal site is located approximately fifty miles off shore of the Golden Gate. Because the Hamilton site is located so much closer to point of origin, the air impacts are lessoned significantly when material is brought to the restoration. Furthermore, disposal at the ocean site requires ocean-going barge tugs and scows which generate more diesel emissions than bay-running equipment. The Army Corps has specified in recent contact solicitations that onsite construction equipment comply with the latest emissions standards for diesel trucks (e.g. particulate filters). Lastly, in 2007, the project opted to grind its own road base by recycling onsite concrete from the former Airfield runway and taxiways rather than import rock from a Marin county quarry. This reduced heavy truck traffic transiting to the site by 80-85%.