Mr. Steve Solomon
City, of Berkeley
2120 Milvia Street
Berkeley, CA 94704

Re: Congregation Beth El Synagogue and School, 1301 Oxford Street, Berkeley

SCH# 2000022024

Dear Mr. Solomon:

We have received the above-referenced Draft Environmental Impact Report (DEIR) and offer the following comments on areas in which the Board is interested.

Regional Water Quality Control Board (Board) staff applaud the project sponsor's 'intentions to protect and restore Codornices Creek and to reduce overall environmental impact of the proposed project. However, Board staff have some concerns about the project's potential to cause erosion and stormwater pollution and impact the creek if adequate mitigation measures are not included in the project design. To address these concerns, the project applicant should augment the Best Management Practices (BMPs) and mitigation/ pollution control measures described in the DEIR to minimize impervious surfaces, to provide better stormwater detention and control, and to better stabilize the banks of Codornices Creek.

Project Description

Congregation Beth El proposes to construct a synagogue, school, and associated facilities on a 2.16-acre parcel in the North Berkeley hills that currently contains an unused church and other buildings. These existing structures, which include impervious surfaces cover approximately 10% of the project site, would be demolished and replaced by structures with a 24,100 square foot (s.f.) footprint, and an additional 13,020 s.f of driveway and parking surfaces. The total impervious surface area would be up to 39% of the parcel, depending on the amount of permeable paving surface used. Codornices Creek separates the northern third of the parcel from the southern two-thirds. The creek is culverted for the eastern 200 feet of its traverse, and above ground for the western 100 feet. The creek's steep banks are being undercut, and pose a significant erosion hazard.

Potential Impacts:

Without proper control and mitigation measures, the project could result in the following.

• Stormwater pollution impacting, waters of the State of California could occur if pollutants on the construction site, such as fuel, oils, and metals from construction vehicles, were mobilized by runoff water and entered storm drains.

• The up to 390% increase in impervious surfaces on the site could also cause a long-term increase in the volume and changes in the timing of stormwater leaving the property. This could result in increased mobilization of the same pollutants identified for the construction period, as well as increased bank erosion and scouring at and downstream of the project site.

• Further erosion of the banks of Codornices Creek may occur if the unstable lower banks are not adequately stabilized.

Congregation Beth El proposes to protect the open third of the creek by laying-back the upper half of the bank to a 2:1 gradient, making, the average gradient 1.5:1 (DEIR, p.4.5-13), and by rip rapping the toe of the bank to stabilize it (DEIR, p.4.5-19). The Congregation would also construct three gabion walls on the mid to upper south bank of the creek and plant the banks with Longleaf Mahonia (lower bank) and Rhododendron (upper bank) (DEIR, p-4.5-1 3).

During the construction period, the Congregation would implement erosion control measures consistent with NPDES Phase II Storm Water regulations. These will include restricting grading to the dry season, covering, and stabilizing graded slopes, protecting storm, drains, and installing siltation fencing, etc. The Congregation proposes to mitigate construction period and Iong-term erosion due to increased storrnwater runoff by the installing energy dissipaters at all major drain outfalls to Codornices Creek.

The project design also includes long-term stormwater control measures such as permiable pavement surfaces, grassy swales and catch basins, although specific information on the size, number, and locations of swales is not provided in the DEIR.

Board Staff's Comments and Recommendations

Stormwater Control

• To prevent stormwater pollution during the construction period, the project's SWPPP should include the onsite capture and treatment of 100% of polluted runoff during the construction period. Specifically, the Congregation should implement thorough erosion and sediment controls on the entirety of the site as proposed on page 4.5-18 of the DEIR.

• The SWPPP should also include specific long-term stormwater control measures that would capture and treat 80-90% of the site's estimated average annual runoff. These measures could include the proposed vegetated swales and storm drain inlet filters. Regardless, the final DEIR should include specific stormwater control design measures and a requirement that the controls will be sized adequately to treat this portion of the site's anticipated stormwater. In the Livermore and Palo Alto area, 80 - 90% of all precipitation occurs m 1-inch to 1.2-inch storm events. The Congregation should obtain similar information for the project area and design stormwater mitigation accordingly.

• Furthermore, because swales have a limited ability to slow or reduce peak flows, and because extreme operating conditions and/or improper maintenance have a tendency to greatly reduce the efficiency of catch basins, Board staff recommend additional stormwater mitigation that would detain the appropriate number of inches of runoff during a rainstorm. The cisterns proposed in the DEIR and Questa. Engineering's "Hydrology, Water Quality, and Stream Corridor Protection (p. 17) provide adequate detention and peak flow runoff reduction.

• In order to further reduce stormwater pollution to the Creek, Staff recommend that the project include the maximum possible setbacks from the regraded streambanks. Vegetating these setbacks as buffer strips might be an effective additional stormwater control measure. In particular, the Congregation should situate the one-way driveway and parking spaces as far from the creek as possible, as these will be the primary sources of pollutants on the site.

• The Congregation should be careful to avoid the discharge of any water used to irrigate ornamental plants into the creek. This water contains chloramine (a residual disinfectant), and dlscharging it to the creek could have a significant negative impact on aquatic life there.

• More information on stormwater control is included in the Board's General comments (attached).

The bank stabilization measures proposed in the DEIR are significant and progressive, but they may not be adequate to prevent negative impacts to the beneficial uses of Codomices Creek, such as steelhead trout habitat, from streambank erosion.

• The Congregation's proposal to lay back the upper banks of the exposed section of Codomices creek to a 2:1 gradient is a good one. This stabilization measure should be applied to the entirety of both banks, and not merely the top half. This will return the bank to a more natural angle and reduce future erosion. Without this measure, the banks may continue to erode despite riprap at the toe, resulting in entire bank slumps that would render the Congregation's other proposed stabilization measures ineffective.

• In place of the stone gabion retaining walls proposed in the DEIR, Board staff encourage the congregation to consider "softer" alternatives, such as those proposed in the Geology Report. One such alternative that might be well suited to this project is a log crib wall (for an example, see Ann L. Riley, Restoring Streams in Cities, p.392-3).

• Staff support the Congregation's intention to stabilize the streambanks with "appropriate riparian vegetation" (4.5-13). However, while the plants proposed in the DEIR, Longleaf Mahonia and Rhododendron, are California natives, they are not appropriate to streambanks in the Berkeley hills, both because they are not native to this environment, and because their relatively shallow roots make them less effective at stabilizing streambanks than deeper-rooted native vegetation. Staff recommend that the Congregation consult with the California Department of Fish and Game or other appropriate professionals to determine the ideal type of vegetation for this restoration project.

• Although the energy dissipaters that the Congregation intends to install where drainage outfalls impact streambanks may mitigate erosion at that point, they may not provide any net mitigation to Codornices Creek as a whole. While this measure will protect the point of impact of each outfall, any increase in stormwater volume and energy due to an unmitigated increase in impervious surfaces would still erode banks downstream, increasing sediment levels in Codornices Creek, and constituting, a significant water quality impact. To effectively mitigate this impact, the project SWPPP should include the stormwater control measures described above, such as detention mechanisms and an adequate number of well-designed swales.

• Staff strongly encourage the Congregation to daylight the culverted 200 feet of Codornices Creek on the project site, and include it in the project's streambank restoration plans. This action would have substantial benefits for aquatic life in the creek.

I have also attached a copy of our General Comments, which discuss the Board's area of responsibility, and which should help guide in the preparation of further CEQA documentation. If you have any questions, please contact me at (510) 622-2380 or e-mail me at KHL@rb2.swrcb.ca.gov.

Sincerely,

Keith H. Lichten
Water Resource Control Engineer