Proposed Mid-Bay Crossing (2002)

Excerpt from San Francisco Bay Crossings Study: Environmental and Socio-economic Report,
June 2002, pages 21-24, prepared for the Metropolitan Transportation Commission
(Full report at www.mtc.ca.gov/library/bay_crossing/Env-Socio-Eco.pdf)



The construction of a new freeway link between the existing SR238/I-880 interchange and the beginning of a new mid-Bay bridge could cause very significant land use and right-of-way impacts to existing neighborhoods in the City of San Leandro and the unincorporated communities of San Lorenzo (west of I-880)and Ashland (east of I-880). The connection between the existing I-238 and the new freeway bridge would be accomplished by a tunnel constructed with a combination of cut-and-cover and boring techniques. The most significant impacts would be to several major commercial structures and apartment buildings west of the existing SR 238/I-880 interchange. This alternative and its likely environmental impacts are conceptuallyillustrated in Figure 5. [Figure omitted]

The alignments of the proposed freeway connectors would require some cut-and-cover excavation, or cut/fill. The connectors would directly affect most structures of a major shopping center (Greenhouse Marketplace) in the City of San Leandro at Lewelling Boulevard/Washington Avenue. The main tenant in the northern portion of the shopping center (Safeway) would be directly affected by cut or fill. Tenants in the southern portion of the shopping mall would be forced to relocate, and tenants in two other separate buildings within shopping center site may also require relocation.

West of the shopping center, at the southeastern quadrant of the Lewelling/Washington intersection, two large apartment buildings and a Walgreens drug store would require removal. The two-story apartment buildings contain an estimated 100 units. Connecting ramps between I-880 and the new freeway could also directly impact a new multiple family structure currently under construction on Embers Way south of Lewelling Boulevard.

On the east side of I-880, construction of the northbound connector to the new freeway would take at least one commercial structure at Lewelling/Hesperian and could also require the removal of numerous single family homes along Via Arroyo adjacent to the existing soundwall.

The new freeway would descend into a tunnel east of the San Lorenzo Creek flood control channel, and west of the Walgreens drugstore on Washington Avenue. The tunnel would emerge within the channel at a point just east of the railroad tracks. The new freeway tunnel would be constructed underneath the channel with state of the art boring technology that theoretically would not affect the waterway or structures within the area. Thus, the residences along Vining Drive in San Leandro (north side levee) and along Via Hermana and Via Bregani south of the San Lorenzo Creek flood control channel should not be affected by construction or operation of the freeway. However, as noted above under the discussion of Alternative 2, the environmental issues associated with using the new tunnel boring technology are difficult to assess and are beyond the scope of this preliminary environmental evaluation.

As noted above, the tunnel would emerge east of the former SP railroad tracks, near the field behind Challenger School, and would become a separated, elevated causeway. Three lanes each would be constructed with soundwalls on single piers on top of the levees along each side of the flood control channel. Construction of this portion of the elevated freeway could have direct impacts to some of the single family residences located adjacent to the northern and southern channel levees at the point east of the railroad tracks. Some of the homes along the north levee appear to be located very close to levees of the channel. The top of the levees is fairly narrow (approximately 50 feet), and are gravel-covered with little vegetation. The levees are not open to public access. Construction of three directional lanes on an elevated freeway supported by a single pier on the top of the levees could impact approximately 20 homes along the north levee and 10 homes along the south levee.

West of the railroad tracks, the recently constructed Heron Bay subdivision is located north of the channel. The flood channel west of the railroad tracks is wider than the channel east of the tracks. It appears the nearest homes are not located as close to the top of the levee as the older homes east of the railroad tracks. Land uses located south of the channel are industrial and would not be affected directly.

Potential mitigation for the impacts to the single family homes north and south of the channel where the tunnel emerges would be to place the piers which support the three directional lanes of the new freeway within the channel itself, away from the levees and residences. It is unknown if this design would seriously compromise the flood control function of the San Lorenzo channel.

The toll plaza for the new mid-Bay bridge would be located on tidal lands west of the railroad tracks and north of the San Lorenzo Creek channel. It appears that there is not enough land between the railroad tracks and the edge of Bay mudflats to locate the toll plaza and the bridge connection without requiring some fill of the Bay. The toll plaza design and operation would be similar to the existing plaza at the San Mateo Bridge. It would include 14 lanes and be approximately 500 feet wide. At least 15 acres or more of salt marsh habitat would be affected.

See also Bay Crossings Study Final Report (July 2002).