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Home My WebLink AboutXC2022-1891 - Alternative Material & Methods (4)eOMMUNITY DEVELOPMENT '�; '° CITY OF NEWPORT BEACH COMMUNITY DEVELOPMENT DEPARTMENT LU}py 11 BUILDING DIVISION 100 Civic Center Drive I P.O. Box 1768 1 Newport Beach, CA 92658-8915 www.newoortbeachca eov 1 (949) 644-3200 CASE NO.: ^%%" REQUEST FOR MODIFICATION TO PROVISIONS OF TITLE 9 (FIRE CODE) OR TITLE 15 (BUILDING CODE) OF THE NEWPORT BEACH MUNICIPAL CODE (See Reverse for Basis for Approval) (Fee $297) ® REQUEST FOR ALTERNATE MATERIAL OR METHOD OF CONSTRUCTION (See Reverse for Basis for Approval) (Fee $297) For above requests, complete Sections 1, 2 & 3 below by printing in ink or typing. FOR STAFF USE ONLY 0EC: 2 2 202Z CIT°t 01-' 114POR.r xna°a�`-any Plan Check # & rZ # of Stories Occupancy Classification /Sb Use of Building A418BD UC X # of Units Project Status (7u D�,R PIA-Al 6HR(Ir Construction Type :T IF Verified by e2 /M k A S R 61. No. of Items i Fee due DISTRIBUTION: ❑ Owner Petitioner 0 Plan Checky-- Inspector Fire ❑ Other U JOB ADDRESS: I PETITIONER:11 SITE ADDRESS: 11022ND ST. Owner McFadden Place LLC Address 3334 E. Coast Hwy. #418 Corona Del Mar, CA Zip 92625 Daytime Phone ( 949 ) 813-5683 Petitioner Brandon Architects Inc. - Ryan McDaniel AIA (Peflflonerto M1e arcM1ifeaf or englnae Address 151 Kalmus Dr., Suite G-1 Costa Mesa CA Zip 92626 Daytime Phone ( 714 ) 754-4040 Email: ryanC. brandonarchitects com CBC 1808.7.4 Petitioner's CA Prof ri nc n i Nrcn -35 eCT Signature � CA Professional Lic. # C-35732 Date: 10/14/22 FOR STAFF USE ONLY DEPARTMENT ACTION: In accordance with: FCBC 104.11/CFC 104.9 ❑ CBC 104.10/CFC 104.8 (Alternate materials & methods) (CBC Modification) ❑ Concurrence from Fire Code Official is required. ❑ Approved ❑ Disapproved ❑ Written Comments Attached _ By: Date Request (DOE OES IUOT) lessen any fire protection requirements. jRequest (DOE(�DOES NOT))lessen the structural integrity The Request is: Ljc. Granted ❑ Denied (See reverse for appeal information) ❑ Granted (Ratification required) Conditions of Approval: PositionF D',!!.-'..)NG 0N-FICIA[Date &PEik 0 -f 3—Zti L-e, APPEAL OF DIVISION ACTION TO THE BUILDING BOARD OF APPEALS (See Reverse) (Signature, statement of owner or applicant, statement of reasons for appeal and fling fees are required.) CASHIER RECEIPT NUMBER: gc-W6311--7S0ZZ Forms\modif 07/08/22 HYDROLOGY STUDY 106,108,110 22°d Street Newport Beach, California Lots 9, 10, 11, Block 21, BK3-26 MM Plan Check No. PC2022-1952 Job No. 22009 Prepared for: McFadden Place, LLC 3334 E. Coast HVVY #418 Corona del Mar, CA 92625 Contact: Mr. Mario Marovic, Managing Member Prepared by: Toal Engineering, Inc. 139 Avenida Navarro San Clemente, CA 92672 Tel: (949) 492-8586 Fax: (949) 498-8625 December 19, 2022 ............................................................... Adam Toal R.C.E. 59275 JN 22009 1.0 PURPOSE This report has been prepared to accompany the Precise Grading and Drainage Plan for the proposed construction of a mixed -use building at 110 22nd street, (Lots 9, 10, & 11, Block 21) (City of Newport Beach Plan Check No. PC2022-1952). 2.0 DESCRIPTION OF SITE The existing 0.162-acre (7,082.90 sq. ft.) project site consists of a developed retail/commercial building on lots 9 and 10 and a residential building on lot 11. The property is bounded on the northwest by 22Id Street, on the southwest and southeast by public alleyways, and on the northeast by a similar retail building. There is parking at the rear of lots 9 and 10. Site soils are classified as Hydrologic Soil Group D per the Orange County Hydrology Manual (OCHM) Soil Maps. The project site is located in Zone X (0.2% annual chance flood hazard) per FEMA Map Panel 06059C0381K. See Figure 1 for a depiction of the project location, Figure 2 for an aerial photograph of the site, Figure 3 for a portion of the OCHM Soils map, and Figure 4 for a FEMA FIRMette map, all in Appendix A. 3.0 EXISTING DRAINAGE Runoff from the project site flows generally as surface flow directly to the right of way in the alleyways. 4.0 PROPOSED DEVELOPMENT The developer proposes to construct a mixed -use building with retail and residential spaces, together with appurtenant hardscape, landscape, and drainage improvements. The proposed improvements are shown on the construction plans for the project, including the Precise Grading and Drainage Plan referenced above. 5.0 PROPOSED DRAINAGE Most of the site is covered by the proposed building. Downspouts connect to underground infiltration trenches below the covered parking areas. Exposed areas have been designed to direct runoff into the alleyways. There are two covered sump areas (DMAs A and B on the Hydrology Map in Appendix Q. Runoff from these sump areas is collected in drain inlets and conveyed to the proposed infiltration trench along the alley on the southwest side of the property. If runoff exceeds the infiltration trench capacity, overflow will enter a proposed lift station designed for the 100-year storm. The pump conveys runoff to a drain box that allows runoff to gravity flow to the curb on 22nd Street. The finished floor elevations of the existing buildings are 10.61', 10.54', and 10.39'. The proposed building top of slab elevations are 10.32' and 10.00'. The architectural and structural plans provide stem walls that extend to elevations ranging from 10.67' to 11.67'. These elevations exceed the street and alley flow lines by over 12 inches. As required by NBMC 15.10.060 and CBC 1808.7.4, drainage to the points of discharge (public alleyways and streets) and away from the proposed structures is provided at all locations on the site. 6.0 METHODOLOGY The pre -project conditions and post project conditions are both fully impervious, so there will not be any changes in calculated runoff quantities between the pre -conditions and post conditions. The study focused on the proposed parking area that is in aswnp condition. A proposed pump is designed to discharge drainage for the 100 year storm event. For post -project conditions, we analyzed sump drainage subareas and performed a rational method hydrologic analysis based on Orange County Hydrology Manual (OCHM) Section D to estimate the peak runoff quantities discharged to the pump. The site time of concentration was conservatively estimated to be 5 minutes, which is the minimum allowed by the OCHM. Peak runoff quantities were compared to the full flow capacity of the pipes discharging from each subarea to ensure adequate drainage system capacity. The full -flow capacity of proposed drain lines was estimated using the Manning Equation. Calculations are shown in Appendix B. The Drainage Map in Appendix C graphically depicts the project watershed and data relevant to the runoff calculations. 7.0 RESULTS AND ANALYSIS Our hydrologic and hydraulic analysis of the site yielded the following results: Table I. 100-Yr Peak Runoff. Subarea Qloo cfs A 0.05 B 0.10 C 0.26 Total 0.23 Table 2. Pipe Capacity Verification. Pipe Size (in) Qioo (cfs) Srrequired So proposed So> Sr 1 4 0.05 0.0007 0.020 Yes 2 4 0.02 0.0153 0.016 Yes Table 2 shows for all pipes the proposed pipe slope is greater than the friction slope required to discharge the design flow rate. This is a conservative comparison since the available friction slope is greater than the proposed pipe slope. 7.1 Pump Analysis For overflow from the infiltration trench from Subareas A and B that drains to the storm water lift stations, calculations for the required Q and required Head can be found in Appendix D. The required Q was calculated to be 0.410 cfs (184 gpm) and the proposed design capacity is 190 gpm 8.0 CONCLUSIONS The proposed storm drain system has sufficient capacity to convey estimated peak 100 year storm discharges to the community storm drain system.