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HomeMy WebLinkAbout1997-12-08 City Council (16)TO: City of Palo Alto City Manager’s Report HONORABLE CITY COUNCIL 7 FROM:CITY MANAGER DEPARTMENT: PUBLIC WORKS DATE: SUBJECT: DECEMBER 8, 1997 CMR:487:97 RECOMMENDATION TO AUTHORIZE AN APPEAL oF PROPOSED FLOOD ELEVATION DETERMINATION IN THE FEDERAL EMERGENCY MANAGEMENT AGENCY’S REVISED FLOOD INSURANCE RATE MAPS FOR SAN FRANCISQUITO CREEK RECOMMENDATION Staff recommends that Council: Direct the Public Works Department to prepare an appeal of the revised San Francisquito Creek Flood Insurance Rate Maps. Direct the Public Works Department to conduct a community meeting in mid to late January to present the revised San Francisquito Creek Flood Insurance Rate Maps to the public for review and comment at that time. BACKGROUND On September 29, 1997, staff reported to Council that the Federal Emergency Management Agency (FEMA) had completed its study of San Francisquito Creek and had submitted a preliminary copy of the revised Flood Insurance Rate Map (FIRM) to the City (CMR:402:97). The revised maps add approximately 800 Palo Alto properties to the Special Flood Hazard Area (SFHA), a 60 percent increase in the number of Palo Alto properties subject to flooding from San Francisquito Creek. Properties within the SFHA are subject to special building requirements and must be covered by flood insurance if mortgaged through a federally-backed institution. Several steps must take place before the revised FIRM will become final and binding on the City 0nd its residents. In its report, staff provided a pr, eliminary outline of the individual steps in the map revision process, which included returning to Council to discuss the City’s options for responding to the revised FIRM and recommending whether or not an appeal of the maps is warranted. This report makes that recommendation. CMR:487:97 Page 1 of 6 DISCUSSION Staff met with FEMA representatives on September 26, 1997 to clarify the scope and timing of the map revision process. As a result, staff has refined the process outline to reflect the latest input from FEMA (Attachment A). The steps in the process remain unchanged, but some of the dates have been extended beyond staff’s original estimated dates. It is anticipated that the public notice triggering the 90-day map appeal period will be published in the Palo Alto Weekly on Wednesday, January 14, 1998. The cities of Menlo Park and East Palo Alto have also received their preliminary revised FIRM’s delineating the San Francisquito Creek floodplain in their jurisdictions, and their staffs will be meeting with FEMA representatives in mid-December. It is anticipated that the map appeal periods will run concurrently in all three cities. Staff is seeking Council direction on whether to file a map appeal with FEMA and whether to conduct a community meeting about the revised FIRM in order to receive public comment at that time. Map. Appeal FEMA’s map revision process includes a 90-day appeal period, during which the City or members of the public have the right to appeal the revised maps based upon a dispute of a quantitative, technical nature. In order to assess the probability of a successful appeal, staff has requested a copy of FEMA’s study file (including correspondence, mapping, engineering calculations, and other documentation). Staff has also consulted with Nolte and Associates, Inc., a local engineering firm familiar with FEMA policies and procedures, for advice on formulating an appeal strategy. FEMA’s map revision process allows the City or members of the public to appeal the revised FIRM by challenging the methodology used to conduct the flood study, disputing the accuracy of the study, or providing new or improved information not available at the time of the study. Appeals fi~om members of the public are first submitted to the City for review. All appeals must be submitted within the 90-day appeal period to Michael Baker Engineers, a FEMA contractor hired to act as an objective third party reviewer. When forwarding the public’s appeals to Michael Baker Engineers, the City may include written comments on staff’s assessment of the validity of the appeals. At the request of staff, Nolte and Associates conducted a brief review of the study documents and contacted FEMA’s study contractor and representatives at Michael Baker Engineers in order to formulate a recommended appeal strategy. Staff and Nolte representatives have identified four key issues as potential grounds for an appeal of the FIRM: CMR:487:97 Page 2 of 6 Outdated hydrology: The projection of creek flows in a one percent floodI event is dependent upon the hydrologic data (rainfall and stream flow quantities) used in the modeling. The hydrologic information used to prepare the existing FIRM is based on historical rainfall and stream flow records available in 1978. Using this data, the projected one percent flow rate for San Francisquito Creek equals 7,860 cubic feet per second (cfs) at the United States Geological Survey gage station near the Stanford Golf Course. Using data updated to include recent rainfall records, the estimated flow rate decreases to 7,583 cfs. FEMA policy dictates that hydrologic data used for flood insurance studies is not revised unless the updated data varies by more than a specified threshold from the old data. In the case of the San Francisquito Creek study, the difference between the two data sets did not exceed the FEMA-specified threshold; therefore, FEMA directed the study contractor to use the old hydrologic data to perform the new flood analysis. Use of the updated hydrolOgic information would have reduced the projected creek flow by 3.5 percent, and therefore, the amount of water that overtops the creek banks in the one percent flood event. The City could base a map appeal on the argument that FEMA’s policyis flawed and that the updated hydrologic data should have been used in the new study. Overly conservative levee failure assumptions: Earthen levees have been constructed along both sides of San Francisquito Creek upstream of the Middlefield Road and Pope/Chaucer Street bridges in order to increase the creek’s flow capacity. FEMA’s current levee policy assumes that levees will fail if they are not built to a specified height above the predicted high water level. In the event of the one percent flood on San Francisquito Creek, the water is projected to overtop the levees on both sides of the creek (Palo Alto and Menlo Park sides) and spill into the surrounding neighborhoods. FEMA policy assumes that this overtopping will cause the entire levee to fail and be washed away, resulting in still more spilling of water. Furthermore, FEMA policy dictates that the flood map be drawn based on a combination of worst case scenarios wherein only one section of levee on one side of the creek will fail at a time. For example, when determining the floodplain for Palo Alto, the study consultant examined three separate worst case scenarios and superimposed the resulting flood areas. The first scenario assumed that ~ the Palo Alto levee upstream of the Middlefield Road bridge fails (other Palo Alto levees and all of the Menlo Park levees were assumed to remain intact). This assumption concentrates more of the floodwaters into the neighborhood adjacent to the Middlefield Road bridge. The second scenario assumed failure of on_N,g_l the Palo Alto levee upstream of the Chaucer/Pope Street bridge, and the ~The one percent flood has a one percent chance of occurring in any given year. It is sometimes referred to as the 100-year flood, because it is the flood that would be equaled or exceeded on an average of one time every 100 years, measured over a long time period. CMR:487:97 Page 3 of 6 third scenario assumed failure of all of the Palo Alto levees.- The floodplain was mapped as a superimposition of the worst flooding from each of these scenarios. Similarly, the floodplain for Menlo Park was mapped using scenarios concentrating the floodwaters on its side of the creek. ¯ FEMA’s conservative levee policy and use of multiple worst case scenarios results in a larger floodplain than would occur in a single flood event. The City could base a map appeal on the argument that FEMA’s levee policy is flawed and that the floodplain should have been mapped with the assumption that: 1) the levees will remain intact, or 2) all the levees (on both sides of the creek) will fail. Overly conservative floodplain mapping: On the current FIRM, only areas subject to flooding in excess of one-foot deep from San Francisquito Creek are included in the SFHA; areas subject to less than one foot of flooding are not included. On the preliminary revised FIRM, FEMA has directed its study contractor to map all areas subject to flooding of any depth as an SFHA. FEMA’s written policies for floodplain mapping procedures are somewhat vague and subject to interpretation regarding this specific issue. A large portion of the revised SFHA is subject to flooding of less than one foot, and this change in mapping policy is the most significant cause of the large increase in the size of the SFHA on the revised FIRM. The City could appeal the revised map by challenging FEMA’s interpretation of its written policy and arguing that areas subject to flooding of less than one foot should not be included in the SFHA. Inadequate topographical information: After projecting how much water would overtop the creek banks in the event of the one percent flood event, FEMA’s study consultant then used computer software and topographical information (ground elevations) to determine the limits and depths of the resultant floodplain. In discussions with the study contractor, Nolte and Associates learned that the revised flood study was conducted using a minimal amount of ground elevation information, due to study budget limitations. Nolte and the study contractor agree that the floodplain could be mapped more accurately if better topography were available. Staff has determined that the ground elevation information available from the City’s Geographic Information System (GIS) is better (more data points and higher accuracy) than the information used to produce the preliminary revised FIRM. The City could prepare a new floodplain map based upon the irnproved topographical data and use it as the basis of a map appeal. It is unknown, however, whether the size of the floodplain would increase or decrease using better information, but it would certainly be more accurate. Nolte has advised against a map appeal based upon the arguments presented as Issues 1 and 2 above. These arguments are a direct challenge of FEMA’s adopted policies, which are applied uniformly on studies nationwide. Furthermore, it is important to note that the engineering firm that would review the City’s appeal is the same firm that has already CMR:487:97 Page 4 of 6 reviewed and endorsed the original flood study and revised FIRM. Therefore, it is unlikely that an attempt to discredit the existing study based on a challenge of FEMA’s policies would be effective. The best chance for a successful appeal appears to be a combination of the strategies outlined as Issues 3 and 4 above. Nolte has recommended that the City prepare its own flood analysis and mapping using the improved topographical information. The map could be prepared to differentiate between areas subject to flooding of less than one foot and areas where the flooding would be one foot or more. The appeal would include arguments for why the SFHA designation should be reserved for the flood areas over one foot deep. Unless otherwise directedby Council, staff intends to contract with Nolte and Associates to conduct a restudy of the flooding potential from San Francisquito Creek using improved topographic data. Staff has negotiated the terms of an agreement with a scope of work totaling approximately $45,000 which can be approved under the City Manager’s authority. The restudy is estimated to take approximately two months to complete. The results of the restudy and its impact on the size and configuration of the SFHA are unknown at this point. Staff recommends that Council’ direct the Public Works Department to continue to pursue an appeal of the FIRM, based upon the strategy described above. Staff will provide Council with an informational staff report after the Nolte and Associates study has been completed with a review of the results of the analysis and a copy of the appeal as submitted. Communi _tT Meeting In accordance with federal regulations, FEMA is only required to publish a public notice in the local newspaper announcing the release of the revised flood insurance maps. It is not obligated to conduct a public hearing or community meeting. Local FEMA representatives have offered, however, to take part in a community meeting hosted by the City. Such a meeting would provide the opportunity to present the maps to the affected public, explain the map revision process, receive public input, and answer questions. Due to the anticipated high level of interest and the substantial potential impacts to local residents and businesses, staff plans to hold a community meeting in mid to late January 1998. It is further recommended that the public input on the map revision issues as detailed above be taken at that time, and that the public discussion over this item be limited to the issues of whether to file an appeal and hold the public meeting. That direction is recommended because staff will have more definitive information regarding the specific timeline once FEMA actually publishes the public notice in January 1998. RESOURCE IMPACT Funds for the Nolte and Associates flood study are available in the Storm Drainage Collection System Improvements Capital Improvement Project. This money is available for the study as a result of favorable bids received for the Barron Park Storm Drain Improvements Capital Improvement Project in September 1997. Staff will include a Budget Amendment Ordinance in the mid-year budget actions to transfer the needed funds fi’om the Capital Improvement Program to the operating budget. CMR:487:97 Page 5 of 6 POLICY IMPLICATIONS This report does not represent any change to existing City policies. TIMELINE If directed by Council, staff will conduct a community meeting in mid to late January 1998 to present the revised Flood Insurance Rate Maps to the affected public, explain the map revision process, receive public input, and answer questions. If directed by Council to pursue an appeal of the revised Flood Insurance Rate Maps, staff will provide Council with an informational staff report prior to the end of the 90-day appeal period with a review of the findings of the Nolte and Associates study and a copy of the appeal as submitted to FEMA. ENVIRONMENTAL ASSESSMENT Council’s consideration of whether to appeal the Flood Insurance Rate Map is not a project for purposes of the California Environmental Quality Act (CEQA). ATTACHMENT Outline of Map Revision ~rocess PREPARED BY: Joe Teresi, Senior Engineer- DEPARTMENT HEAD REVIEW: CITY MANAGER APPROVAL: CC." City Manager Ken Nauman, FEMA Ray Lenaburg, FEMA Kay Whitlock, Santa Clara Valley Water District Randy Talley, Santa Clara Valley Water District San Francisquito Creek CRMP coordinator, Peninsula Foundation Susan Frank, Palo Alto Chamber of Commerce Cathy Lehrberg, Crescent Park Neighborhood Association Eric Morley, Peninsula West Valley Realtors Association Laura Alms, Peninsula West Valley Realtors Association John Paul Hanna Conservation Center CMR:487:97 Page 6 of 6