APPENDIX I HAZARDS AND HAZARDOUS MATERIALS DATA

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1 APPENDIX I HAZARDS AND HAZARDOUS MATERIALS DATA

15 September 30,2005 Mr. Wade Brown Project Director city of Laguna Beach 505 Forest Avenue Laguna Beach, California RE: Lifeguard Headquarters, Riverine Flooding at the Mouth Laguna Canyon Creek, Laguna Beach, California Dear Wade: I am writing you to summarize our findings regarding the above-mentioned project. We performed a hydraulic analysis of Laguna Canyon Creek at Pacific Coast Highway (PCH) in Laguna Beach, based on the best available data that we had. The following are my observations and assumptions: NAVD88 vertical datum assumed. Invert elevations of inlet and outlet are approximately 4.6 and 3.6, respectively. Low point of PCH road elevation is approximately The culvert outlet, which is currently boarded shut, is temporarily sealed and a major flood event will force the outlet open. Crossing PCH are 2-11'0" x 4'6" RCB, with a length of approximately 240 feet. Tailwater elevation assumed to be 15.4 based on newly adopted LOMR' and revised Zone VE BFEs; using closest cited elevation at Myrtle Street. Design flows: 4,500" and 6,910"'. Resulting headwater elevation is 15.6 so round to 16. Neither the National Flood Insurance Program (NFIP) Library nor Orange County Flood Control found any flood-related information relevant to this project. So we had to rely on our independent hydraulic analysis to determine the impacts of the lifeguard station on the riverine flooding potential. We applied the state-of-the-art one-dimensional culvert hydraulics model, HY~", to model this culvert system. The results are provided in the attached exhibit. Our conclusions and recommendations are as follows: Revise FIRM (LOMR process) SFHA Zone VE to extend up to PCH, thereby eliminating that confusing and misleading gap between Zones AE and VE. This is not critical to your project but should be done sometime in the near future. The PCH culvert system is submerged due to the coastal flooding Mill Creek Drive Suite 210 Laguna Hills, CA Tel: Fax:

16 Lifeguad Headquarters, Riverine Flooding at the Mouth Laguna Canyon Creek, Laguna Beach, California Since PCH is inundated by the coastal flooding (Zone VE), the riverine flooding (Zone AE) does not begin until the upstream side of PCH. The culvert hydraulic analysis revealed that outlet control prevails for the 100-year event. Hence, the riverine flooding is solely dependent on the tailwater characteristics, i.e., the coastal flood elevation. Therefore, the riverine is not impacted unless the Zone VE BFE is changed. Since the proposed Lifeguard Headquarters is located in Zone VE & whose finished floor elevation (FFE) will be constructed above the BFE of 15.4, the Zone VE should not be affected. The coastal engineer can verify this conclusion. I hope this report meets with your approval. Please let me know if you have any questions. Sincerely, RIVERTECH INC. - A. Tamim ~\a~ee, PE/ Vice President Enclosures ' Letter of Map Revision (LOUR), 1021-C, Case No P, October 21,2004. "lood Insurance Study (FIS), Orange County and Incorporated Areas, Federal Emergency Management Agency (FEMA), Volume 1 of 4, iii Lagum Canyon Channel Interim Study, Facility No. 102, Orange County Environmental Management Agency (OCEMA), June " FHWA Culvert Analysis, HY8, Version 6.1, Federal Highway Administration, Washington, DC.

17 1 CURRENT DATE: CURRENT TIME: 17:44:06 FILE DATE: FILE NAME: LGCYNPCH FHWA CULVERT ANALYSIS HY-8, VERSION 6.1 i SITE DATA i CULVERT SHAPE, MATERIAL, INLET i j INLET OUTLET CULVERT j BARRELS i I ELEV. ELEV. LENGTH I SHAPE SPAN RISE MANNING INLET I (ft) (ft) (ft) I MATERIAL (ft) (ft) n TYPE I RCB CONVENTIONAL^ I I I SUMMARY OF CULVERT FLOWS (cf s) ELEV (ft) TOTAL FILE : LGCYNPCH DATE: ROADWAY ITR OVERTOPPING SUMMARY OF ITERATIVE SOLUTION ERRORS FILE: LGCYNPCH DATE: HEAD ELEV (it) HEAD ERROR ( f t) TOTAL FLOW (cfs) FLOW ERROR (cfs) % FLOW ERROR

18 2 CURRENT DATE: CURRENT TIME: 17:44:06 FILE DATE: FILE NAME: LGCYNPCH PERFORMANCE CURVE FOR CULVERT 1-2( (ft) BY 4.50 (ft)) RCB DIS- HEAD- INLET OUTLET CHARGE WATER CONTROL CONTROL FLOW NORMAL CRIT. OUTLET TW OUTLET TW FLOW ELEV. DEPTH DEPTH TYPE DEPTH DEPTH DEPTH DEPTH VEL. VEL. (c~s) (ft) (ft) (ft) <F4> (ft) (ft) (ft) (ft) (fps) (fps) El. inlet face invert 4.60 ft El. outlet invert 3.60 ft El. inlet throat invert 0.00 ft El. inlet crest 0.00 ft ***** SITE DATA ***** CULVERT INVERT ************** INLET STATION 0.00 ft INLET ELEVATION 4.60 ft OUTLET STATION ft OUTLET ELEVATION 3.60 ft NUMBER OF BARRELS 2 SLOPE (V/H) CULVERT LENGTH ALONG SLOPE ft ***** CULVERT DATA SUMMARY... BARREL SHAPE BOX BARREL SPAN ft BARREL RISE 4.50 ft BARREL MATERIAL CONCRETE BARREL MANNING'S n INLET TYPE CONVENTIONAL INLET EDGE AND WALL SQUARE EDGE (30-75 DEG. FLARE) INLET DEPRESSION NONE

19 CURRENT DATE: CURRENT TIME: 17:44:06 FILE DATE: FILE NAME: LGCYNPCH TAILWATER CONSTANT WATER SURFACE ELEVATION ROADWAY OVERTOPPING DATA ROADWAY SURFACE EMBANKMENT TOP WIDTH CREST LENGTH OVERTOPPING CREST ELEVATION PAVED ft ft ft

20 Federal Emergency Management Agency Washington, D.C OCT CERTIFlEDMAIL, RETURN RECEIPT REQUESTED IN REPLY REFER TO: Case No.: P The Honorable Cheryl Kinsman Community City of Laguna Beach, CA Mayor, City of Laguna Beach Community No.: Forest Avenue Panels Affeded: 06059C0412 H, 0416 H, Laguna Beach, CA H, 0419 H, 0438 H, and 0501 H Effedve Date of 0 CT This Revision: Dear Mayor Kinsman: On April 24,2004, the Department of Homeland Seuuity's Federal Emergency Management Agency (FEMA) initiated a revision to the effective Flood Insurance Rate and Flood Insurance Study (FIS) report for Orange County, Calif& and Incorporated Areas (the effdve FIRM and F'IS report for your community), in accor&nce with Part 65 of the National Flood Jnsmmce regulations FEMA is revising the FIRM and FIS report to change a previous conversion of the FIRM from the National Geodetic Vertical Datum of 1929 the North American Vertical Datum of 1988 along the P d c Ocean coastline from approximately 700 feet west of the intersection of Riviera Drive and Monte Carlo Drive to approximately 600 feet south of the intersection of La Senda PIace and La Senda Drive. We have completed our review of the submitted data and the flood data shown on the effective FIRM and in the effective FLS qxnt We have revised the FIRM and FIS report to modify the elevations of the flood having a 1-percent chance of being equaled or exceeded in any given year (base flood) along the Paac Ocean coastline hm approximately 700 feet west of the intersection oeriviera Drive and Monte Carlo Drive to approximately 600 feet south of the intersection of La Sen& Place and La Senda Drive. As a result of the modifications, the Base Flood Elevations for the P d c Ocean decreased. The modifications are shown on the enclosed annotated copies of FIRM Panels 06059C0412 H, 06059C0416 H, 06059C0417 H, H, 06059C0438 H, and 06059C0501 H and afieded portions of the Summary of Pacific Ocean Wave Elevation Table. This Letter of Map Raision (LO=) hereby revises the above-referenced panels of the effective FIRM and the affeded portions of the FIS report, both dated February 18,2004. Because this revision request also affects the unincorporated areas of Orange County and the Cities of Dana Po& Huntington Beach, Newport Beach, San Clemente, and Seal Beach, separate L OW for these communities were issued on the same date as this LOMR. The modifications are effective as of the &te shown above. The map panels as listed above and as modified by this letter will be used for all tlood insurance policies and renewals issued for your community.

21 If you have any questions regarding floodplain managanent regulations far your community or the NFIP in general, please call the CCO for your community at the telephone number cited above. If you have any questions regaxding this LOMR, please call our Map Assistance Center, toll fke, at FEMA MAP ( ). Sincerely, Max H. Yuan, PE., Projed Engineer Hazard Identification Section Mitigation Division Emergency Preparedness and Response Dbectorate Enclosures For. Doug Bellom, P.E., CFM, Acting Chief Hazard Identification Section Mitigation Division Emergency Preparedness and Response Directorate cc: The Honorable Thomas Wilson Chairman, Orange County Board of Suparvisors The Honorable Joe Snyder Mayor, City of Dana Point The Honorable Cathy Green Mayor, City of Huntington Beach The Honorable Tom W. Ridgeway Mayor, City of Newport Beach The Honorable Susan Ritschel Mayor, City of San Clemente The Honorable Paul Yost Mayor, City of Seal Beach Mr. Steve May Director Department of Public Works City of Laguna Beach

22 Table 9. Summary of Pacific Ocean Wave Eldons (Cont'd) Wave Runup 500 Feet Southwest of Southan Intersection of Circle Drive and Pacific Coast Highway At 5* Avenue Extcnded Southwest At Seacliff Drive Extcnded Southwest At West Strcct Extcnded West Feet Northwest of Alisos Ctodr Fcet Southwest of lotdon of Pacific Coast Highway and Laguuita Line At upload Road Extended Southwest At Diamond Stt.ect Extaded At Mountain Road Extended At Park Avenue Storm Drain At Myale Stt.ect Extcnded Southwest At Bamnca Strut Extended At McKnight Drive Extended South Fat South of I n t ~ oof n Shamrock Road and pacific Coast Highway At Nigud Canyon Fcet Southwtst of lotdon of Circle and Emaad Point Drivts At Monte Carlo Drive Extended Southwest Wave Setup ~le~liccr (ket NAVDJ Elevation (Feet NAVD) 100h annual 1% annual 0.2% annual 100? annual 1% annual 0.2% annual chance c)lanct S!m!Z chanq chance &q 400 feet West of Intersdon of Riviera and Monte Carlo Drives REFLECT LOMR

23 Table 9. Summary of Pacific Ocean Wave Elevations (Cont'd) Wave Runup 400 Fed Southwest of East Garden Grove Wmtaburg Channd Dam At Sceptxe Lam Extended South At Weathaiy Lane Exteadad South ,200 Fect Southwest of btuscction of Wcathuiy Lane and Warner Avenue Wave Setup Ele~tion (Feet NAMj Elevation (Feet NAM) 10% annual.i% annual 0.2% annual lo?? annual 1% annual 92% annual &4EG &!Ss chance ~hance fiance chance At 14* street Exteadad Southwest At Andason Street Extaided Southwest At Huntington Harbor At intersection of M c Coad Hwy and Wama Avenue Philip Sh-eet Extended Southwest At Dolphin Avenue Extended Southuest At Anaheim Bay 7.2 At loq Street Extmded Southwest At 9 Street Extended Southwest Conflutnce with San Gabriel River 1. Avetage Elevation Along Coast in Vicinity of Each Location REVISED - - TO REFLECT ~ LOMR

24 Table 9a Inland Flooding Elevations (Cont'd) Elevation (Feet NAVD) 10% annual 1% annual 0.2% annual chance chance chance Huntfngton 8each Channel - East Banh Belween Banning Avenue. MagnoSa Street and Bermuda Cirde extended Between Levee. Newbnd Street. Hamilton Avenue, and Surveyor Cirde Between HmUton Avenue. Newland Sbveet. Atlanta Avenue. and Brenkm Lane Between Levee, Athnta Avenue. and Newbnd Skeet Between Atlanta Avenue. Newland Street, and Magnolia Street Beween Atlanta A-. khstef m. and Newland Street Between Munster Drive. Adams Avenue, and Waterfront Lane Between Waterfront Lane. Northport Drive. and Port Greenwich Lane as Elevation mt computed REVISED TO REFLECT LOi\JIR DATED OCT 2 I 2004

Evaluation of June 9, 2014 Federal Emergency Management Agency Flood Insurance Study for Town of Weymouth, Norfolk, Co, MA

Evaluation of June 9, 2014 Federal Emergency Management Agency Flood Insurance Study for Town of Weymouth, Norfolk, Co, MA Prepared For: Woodard & Curran 95 Cedar Street, Suite 100 Providence, RI 02903