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HomeMy WebLinkAboutCUP 2017-0008; OAKMONT OF CARLSBAD; SEWER REPORT; 2019-08-01I RECiwY I IM3 Io_t SEWER REPOIT iiitjaI Date FOR OAKMONT OF CARLSBAD LOT 1 of CARLSBAD OAKS NORTH Cup 2017-0008 GR2019-0013 DWG. 517-4A Prepared For: Oakmont Senior Living 9240 Old Redwood Highway, Suite 200 Windsor, CA 95482 Prepared By: Alliance Land Planning & Engineering, Inc. 2248 Faraday Ave. Carlsbad, CA 92008 At RCMVET SEP 082819 LAND DEVELOPMENT ENGINEERING OAKMONT OF CARLSBAD CUP 2017-0008 SEWER REPORT TABLE OF CONTENTS Introduction......................................................................................................................................2 PublicSystem Impacts....................................................................................................................3 OnsitePipe Sizing............................................................................................................................3 Conclusion.......................................................................................................................................3 LIST OF APPENDICES APPENDIX A - SEWER EXHIBIT APPENDIX B - SEWER GENERATION FACTORS APPENDIC C - HYDRAULIC MODELING OUTPUT DATA OAKMONT OF CARLSBAD CUP 2017-0008 SEWER REPORT Introduction The following is a Sewer Capacity Analysis Report for the Private Sewer System within the Oakmont of Carlsbad project (Lot 1), which is part of the Carlsbad Oaks North Master project. The private system has been designed using the Uniform Plumbing Code required for private system design. The UPC sets maximum drainage fixture units (DFUs) for pipe sizes and provides DFUs capacity safety factors for pipe grades less than 2.0%. The sewer system within the Oakmont of Carlsbad site has been designed to meet these standards and specifications. Methodology As discussed with City of Carlsbad, Private Systems are not designed according to Public Sewer Design standards (City/County Standard) but using the aforementioned UPC. City design standards for public sewer systems use an alternative methodology for calculating discharge, minimum slopes velocity and capacity which will make the analysis flawed if methods/standards were to both be followed. The Oakmont of Carlsbad sewer system follows UPC guidelines for pipe sizing and is displayed in an exhibit included in Appendix A. Maximum slopes we're applied during design to meet grade of the P.O.C. at the project property line. Capacity in each segment of sewer pipe is designed to sufficiently convey calculated DFUs generated from the 3 proposed buildings. Sewer Generation Below is a summary of sewer generation calculations that compare the existing land use at the site (industrial) to the currently proposed land use (residential, with no kitchen). Oakmont Senior Living Center Flows vs. Original Buildout Model Flows ZONE Building Area (sO I UNITS FACTOR REDUCTION FLOW (gpd) (E) INDUSTRIAL 277,913 - 800 gpd/10,000sf 0.5 1 11,117 (P) RESIDENTIAL, - 151 220 gpd/EDU 0.6 2 19,932 NO KITCHEN 1 Reduction for 50% coverage 2 Reduction for no kitchen use within each unit The proposed sewer generation flow is considered conservative as Carlsbad bases their residential factor at a 220 gpd/EDU rate based on 2.76 residents per unit where Oakmont Senior Living facilities typically only have one resident per unit. In addition, the residents rarely, if at all, are able to use the kitchen facilities within their own unit. Even though the kitchen reduction factor is applied, the 220 gpd/EDU basis is considered an over-estimation of the actual generation within the Oakmont units. OAKMONT OF CARLSBAD CUP 2017-0008 SEWER REPORT Public System Impacts Since the proposed Oakmont land use generates more sewer flow than does the existing site land use, analysis of the City's municipal system is warranted. Proposed site flows of 19,932 gpd were provided to the City to confirm the increase does not significantly impact the existing public system. Impacts were assessed by calculating a proposed Peak Wet Weather Flow (PWWF) within the main servicing the Senior Center, through the use of Hydraulic Modeling. The model analyzed a combination of discharges, including proposed flow from the Senior Center and existing flows generated from two Industrial Parks located upgradient. The proposed PWWF in the sewer main servicing the Senior Center was derived from the model to equal 0.79 mgd. The capacity of the El Fuerte Lift Station was provided by the City to equal 1.40 mgd, therefore deeming the proposed private sewer system acceptable. Model output data and calculations are located in Appendix C. Onsite Pipe Sizing UPC Table 703.2 - Maximum Unit Load and Maximum Length of Drainage and Vent Pipe, was used to determine maximum DFU capacity and pipe size for each onsite sewer lateral and main. Despite calculating maximum pipe slopes throughout the onsite system, some laterals and mains were designed to less than 2.0% grade due to tie-in constraints at the ultimate P.O.C. at the northeast site entrance. Irrespective, the system has been designed using the UPC safety factors for pipes with slope less than 2.0%, resulting in adequate conveyance of design DFU quantities in all laterals and mains throughout the system. A comparison of the design DFU versus the proposed maximum DFU capacity is shown for laterals and mains on the sewer plan included. Conclusion The sewer flows proposed at the Oakmont Senior Living facility are considered conservative in nature. Based on results from the City's analysis for offsite public system impacts, the private sewer system described here is considered acceptable for construction. APPENDIX A SEWER EXHIBIT OAKMONT OF CARLSBAD SEWER AREA STUDY EXHIBIT LOT 1 OF TRACT No. 14926 )N I Vicinity Map NO SCALE BILL OF MATERIALS ITEM DESCRIPTION QUANTIFY STD. DWG. REFERENCE CONNECT TO EXISTING 8" SEWER LATERAL PER DWG 480-3 1 EA DWC 480-3 CONSTRUCT 6" PVC (SDR 35) SEWER LINE 1,120 LF CONSTRUCT 8" PVC (sDR 35) SEWER LINE 550 LF CONSTRUCT SEWER CLEANOUT 24 EA CITY STD. S-6 CONSTRUCT SEWER MANHOLE 2 EA CITY STD. S-i (,- CONSTRUCT 1,200 GALLON CREASE INTERCEPTOR 1 LA 0 25 230 220 N ° 225 - /ao 0 ; 240 \ k \ \7'7 \\ 1 1-000 ill) S 11,000, 10000, /2 7 \\ \\ / /2 / zz / CURB CURB - / / 28' 14' 14' . - / A.C. PAVEMENTJJ COMPACTED 104 / - - - V BASE COURSE SU BGRADE i- PRIVATE DRIVE .7 V NOT TO SCALE - - V - - V 0 0I APPLICANT CML ENGINEER ENVIRONMENTAL, - - -' - - OAKMONT SENIOR LIVING ALLIANCE LAND PLANNING AND ENGINEERING OAKMONT SENIOR LIVING GRAPHIC SCALE 40 0 20 40 80 ( IN FEET ) 1 inch = 40 ft. ...-' ...- . - -' L) rc uvvuuu nVV I iL'FU UL WINDSOR, 2248 r/-\m/-\u/-\i /-\VL JL'+U ULU RCUVVUUU flVV I CA 95492 CARLSBAD, CA 920064 WINDSOR, CA 95492 loe V (707) 535-3200 FAX (707) 535-3299 (760) 431-9896 (707) 535-3200 FAX (707) 535-3299 V ARCHITECT LANDSCAPE ARCHITECT ALl IQBAL LANDESIGN GROUP - .' 9240 OLD REDWOOD HWY 3344 GAVENSTEIN HWY NORTH >- WINDSOR, CA 95492 SEBASTOPO, CA 95472 f7(V7\ 7C)rII\ FAV (lrh7\ 7C)C)C\ (r\ OC)C\ C)7OC\ rAy f7C)7\ OIl') 7A17 2248 FARADAY AVE. CARLSBAD, CA 92008 TEL: (760) 431-9896 FAX: (760) 431-8802 27413 TOURNEY ROAD ALLIANCE SUITE 120 VALENCIA CA 91355 LAND PLANNING & ENGINEERING INC. TEL: (661) 799-2760 FAX: (661) 254-1929 PLANS PREPARED BY: ALLIANCE LAND PLANNING & ENGINEERING INC. 2248 FARADAY AVE., CARLSBAD, CA 92008 (760) 431-9896 PLANS PREPARED UNDE ,XE DIRECTION OF: JASO F. ROOM NO. 61297 .- -,._ I,/UI) UJ.)JLUU 1/-\A I/U/) UUJJL /U/) OLLJOU r/-'.A IfUI) 0L39I/ -5----- PLANS PREPARED FOR: BENCHMARK PROPERTY OWNER: SHEET -i I CITY OF CARLSBAD I SHEET 1 SAN DIEGO COUNTY PUBLIC WORKS BENCHMARK NO.: OAKMONT OF CARLSBAD - OWNER NAME: OAKMONT SENIOR LIVING NO. 61297 z OWNER DESCRIPTION: 2" ALUMINUM DISC STAMPED OPS CONTROL PIT. 2002 EXP 6 SEWER NAME: OAKMONT SENIOR LIVING AREA STUDY EXHIBIT -3 CIVIL STREET 9240 OLD REDWOOD HWY, SUITE 20o IN SIDEWALK NORTH SIDE OF PALOMAR AIRPORT ROAD, STREET 220 CONCOURSE BLVD. SAN DIEGO COUNTY, CALIFORNIA ADDRESS WINDSOR, CA 95492 300—FEET WEST OF MELROSE DRIVE. ADDRESS SANTA ROSA, CA 950403 fl 71 ._.. .__ ........-..___. ,__ 2740 FARADAY AVENUE SQc' .... . -- RFflflRfl FRflA Rn NIn 17771 (PT NI 8/23/19 Al IN: HANNAH DAUGHLRIY (707) 535-3211 '' ,S.. . - ATTN: Al IN: HANNAH DAUGHLkIY (/0/) 535-3211 DATE ELEVATION: 444.00 MSL CARLSBAD, CA 92008 CIVIL ENGINEERING • LAND PLANNING • HILLSIDE DESIGN • SURVEYING APPENDIX B SEWER GENERATION FACTORS I Sf-.. f•'' ---.:, ,.' -. ' '.: -' ... 5'. •." , - spreadsheet for future development in LFMZ I was provided by City Staff. The spreadsheet. which includes parcel numbers, is more detailed than the Growth Database backup sheet and was used to locate future development in LFMZ 1, which is primarily redevelopment in the downtown area. Once future development projections were linked to parcels, a map of future development was prepared and reviewed for accuracy. In the Growth Database, once building permits are issued the development is assigned to that calendar year and is no longer considered future development Construction does not necessarily begin right after permits are issued, however, and it may take several years before developments are occupied and contributing sewer flows. This creates a lag between "existing" and "future" development. Since future flows based on the Growth Database are added to the existing hydraulic model with 2009 wastewater flow data, development projects with recent building permits that have not yet been constructed or are not yet contributing wastewater flows need to be included. To identify these developments, projects in the Growth Database with building permits issued in the past three years were reviewed together with the most recent land use map, aerial photographs, and water use records. This investigation identified developments that were not contributing wastewater flows during the 2009 metering period and resulted in a significant increase in future" development, primarily in some of the newer industrial parks, portions of Bressi Ranch, and In Robertson Ranch, where building permits have already been issued for the first phases. Several additional refinements were also made to the modified parcel-based growth database to account for future flows to the wastewater system. These included? • Future recreation facilities in parks and a future high school in LFMZ 14 were added. Residential properties that currently have septic systems were added on the assumption that they will ultimately connect to the sewer system. These parcels were identified by City Staff based on water and sewer billing records. Residential units within the service areas of the La Golondrina and La Costa Meadows Ill Lift Stations were added to account for the additional flows that have been re-directed into Carlsbad with the construction of new gravity sewers and the recent removal of the lift stations. Buildout projections for the proposed residential development known as Quarry Creek (LFMZ 25) were updated based on updated planning information provided by City Staff. The residential categories were modified to separate high density development (apartment complexes, as noted in the growth database backup sheets) from all other residential development. This was done to more accurately project sewer flows, which are influenced more by the number of people per household than the lot size. Exhibit 2 in Appendix A illustrates the parcels with future development within the sewer service area. 5.3 FUTURE FLOW GENERATION FACTORS Flow, generation factors are used, in conjunction with the modified Growth Database, to project ultimate wastewater flows. Unit flow generation rates were developed and presented in Chapter 3 of this report based on 2009 flow data. For planning purposes. more conservative unit flow factors are typically used. The City's established planning value for wascewater flow is 220 gpdJEDU. Flow factors typically used for design of sewer systems throughout San Diego County range between approximately 200 gpd!EDU in the Cities of Encinitas and Solana Beach, to 250 gpdfEDLJ in the City of Vista. The City City of Carlsbad DUDEI( SEWER MASTER PLAN 5-4 April 2012 of San Diego Water & Sewer Design Guide recommends the use of 80 gallons per capita day (gpcd). which equates to 197 gpd/DU for the City of Carlsbad (based on 2.46 persons per household). Based on these comparisons and the calculated unit flow race for current conditions, the previously established flow generation rate of 220 gpd/EDU is considered to be appropriately conservative for flow projections in this master plan update. A lower unit flow factor of 176 gpd (80 percent of 220 gpd/EDU) is applied to high-density residential units in excess of approximately 20 units per acre (apartment complexes). A non-residential land use flow factor of 800 gpd per 10,000 square feet of building area is applied to commercial and industrial development projections in the Growth Database. The composite commercialfindustrial unit factor was approved by City Staff for planning purposes, and is higher than the average unit .flow calculated in the unit flow analysis documented in Section 3.7. It is noted that projections made using this factor are based on a mix of development types in existing businesslindustrial parks and may not be representative of smaller areas with a single land use type. Flow projections for future schools, resort hotels, and the expansion of the Legoland Water Park are based on EDU conversions documented in the Carlsbad Municipal Code (Table 13.10.020c). The unit flow factors established by City Staff to project uftin'1ate wastewater flows in this Master Plan Update are summarized in Table 5-2, Table 5.2 Wastewater Unit Flow Factors Residential Low Density to Med-Higi Density 220 gpd/DL Pesidenial High Density (Aparnneots) 176 pdJDU Commerclai/lndustrtal 800 gpd/ 10.000 sq ft of building area High School 7.33 gprJ!student Hovel I32 gpd/guest room Water Park (Legoland) 3,740 gpd/developed acre 5.4 PROJECTED ULTIMATE FLOWS Wastewater flow projections for future developments are made by applying the unit flow factors to the future build-out data in the modified Growth Database. Future wastewater flows are projected to be approximately 2.1 mgd and are summarized in Table 5-3. The future flows are based on flow projections for future development, and also include unit counts for existing residences that currently have septic systems and areas in LFMZ 6 that previously were pumped to LWWD from the La Golondrina and La Costa Meadows Lift Stations. It is rioted that a minor wastewater service area boundary adjustment is assumed in the future to serve existing LWWD customers within the area of a proposed residential development located on the west side of El Camino Real, just south of Poinsettia Lane. City of Carlsbad DUDEK. SEWER MAs-rER PLAN 5-5 April 2012 ,1. APPENDIX C PUBLIC SYSTEM HYDRAULIC MODEL OUTPUT DATA Model Output Reference Figure 1. Senior Center 2. Industrial Pack oaf cels contributing flow to gravity main servicing Senior Center areu and Jie Mud arc Rt cc a N iridusir al PaR TrOuta: as Mannoies - Gravity Man 3. Industrial Park parcels tributary to El Fuerte LS but not contributing flows to gravity main servicing Senior Center L \ \ 7•*• 1 rtW Aap° *4 a Summary Tables Table 1. Summary Table for Uodated Flows from Senior Living Center Number from Figure Parameter Value Unit 1 Original Loading for Senior Center Parcel from Hydraulic Model based m d g on Industrial Land Use (Average Dry Weather Flow) 0.0053 1 Updated Loading for Senior Center (Average Dry Weather Flow) 1 mgd 0.020 2 Original Loading for Industrial Park parcels contributing flow to gravity m d g main servicing Senior Center (Average Dry Weather Flow) 0.13 2 Updated Loading for Industrial Park parcels contributing flow to m d g gravity main servicing Senior Center (Average Dry Weather Flow) 0.28 1+2 Total Loading in Gravity Main Servicing Senior Center Parcel Including d Updated Senior Center Flows (Average Dry Weather Flow) 0.30 1+2 Peak Wet Weather Flow in Gravity Main Servicing Senior Center d Parcel with Updated Loading based on Hydraulic Model Output 0.43 1 + 2 Maximum Depth Over Diameter in Gravity Main Serving Senior Center d D Parcel from Hydraulic Model 0.46 Table 2. Summary Table for El Fuerte Uft Station Capacity Check Number from Figure Parameter Value Unit Original Loading for Industrial Park parcels tributary to El Fuerte IS 3 but not contributing flows to gravity main servicing Senior Center mgd (Average Dry Weather Flow) 0.12 Updated Loading for Industrial Park parcels tributary to El Fuerte 1.5 3 but not contributing flows to gravity main servicing Senior Center mgd (Average Dry Weather Flow) 1 0.24 Original Loading for El Fuerte IS Tributary Area Including Senior 1+2+3 Center Flows and Updated Industrial Flows (Average Dry Weather mgd Flow) ° 0.25 Updated Loading for El Fuerte LS Tributary Area Including Senior 1+2+3 Center Flows and Updated Industrial Flows (Average Dry Weather mgd Flow) 0.54 1+2+3 Peak Wet Weather Flow to El Fuerte lift Station Including Updated mgd Loading based on Hydraulic Model Output 0.79 1+2+3 El Fuerte Lift Station Rated Flow 1.40 mgd 1+2+3 Excess Capacity at El Fuerte Lift Station 0.61 mgd - Note 1: industrial flows originally in model based on 24% coverage. Flows were updated based on 50% coverage for this analysis. Table 3. Average Dry Weather Flow Summary Table All Parcels Industrial Park Parcels Industrial Park Parcels Contributing Flow Tributary to El Fuerte 1.5 All Areas Senior Contributing Flow to to Gravity Main but Not Contributing Tributary Center Gravity Main Servicing Servicing Senior Flows to Gravity Main to El Fuerte Parameter Parcel Senior Center Center Servicing Senior Center 1.5 Area Number 1 2 1+2 3 1+2+3 from Figure Original Loading from Model 0.0053 0.13 0.14 0.12 0.25 ADWF (mgd) First Updated Loading with 24% Industrial 0.020 0.13 0.15 0.12 0.27 Coverage ADWF (mgd) Second Updated Loading with 50% Industrial 0.020 0.28 0.30 0.24 0.54 Coverage ADWF - (mgd) Flow Calculation Tables Table 1. Oakmont Senior Living Center Flows vs. Original Buildout Model Flows Number from Figure Parameter Value Unit Explanation 6.4 acres Existing area contributing to main loaded with Oakmont Senior Living Center flows 43,560 sqft/acre Conversion acre to square feet 277,913 sqft Existing area in square feet 24% Coverage Building footprint vs. land use area for single story Industrial Park Land Use ___________ ____________ building 66,699 Building sqft Calculated building area for single story buildings Calculations 1 gpd/sqft Flow factor for Commercial/ Industrial land use 0.08 from 2012 Sewer Master Plan gpd Calculated flow (gpd/sqft* Building sqft) 5,336 mgd Calculated ADWF in mgd (included in model) 0.0053 220 gpd/EDU Sewer Flow Generation Rate per EDU 0.6 Reduction Reduction for Residential with No Kitchen 132 gpd/EDU Sewer Flow Generation Rate per EDU with No Residential Land Kitchen 151 EDU EDUs in El Fuerte/Gateway Senior Living Center Use Flow Calculations 2 gpd Calculated flow (gpd/EDU*number of EDUs) 19,932 0.020 mgd Calculated ADWF in mgd - Note 1: Flows Included in the buildout model scenario for the senior center parcel, originally Industrial Park land use based on 24% coverage Note 2: Flows calculated for the senior center based on EDU count and flow generation rate Table 2. Buildout Peak Wet Weather Flow Calculations (Based on Land Use) and Model Results Number from Figure Parameter Value Unit Explanation Senior 1 Center 0.020 mgd Calculated ADWF in mgd (from Table 1) ADWF Senior Peaking factor for PDWF based on diurnal pattern 1 Center 1.29 - in model (8:00 am) 0.026 mgd Calculated PDWF (PFADWF) PDWF Buildout area contributing to main loaded with 158 acres Oakmont Senior Living Center flows Building footprint vs. land use area for single story Original 24% Coverage building sqft/acre Conversion acre to square feet Calculations for 43,560 Building sqft Calculated building area for single story buildings 2 Upstream Industrial 1,651,560 0.08 gpd/sqft Flow factor for Commercial/ Industrial land use Park Parcels ADWF from 2012 Sewer Master Plan gpd Calculated flow (gpd/sqft Building sqft) 132,125 0.132 mgd Calculated flow in mgd (included in model) Buildout area contributing to main loaded with 158 acres Oakmont Senior Living Center flows 50% Coverage Building footprint vs. land use area for single story Updated building sqft/acre Conversion acre to square feet Calculations for 43,560 Building sqft Calculated building area for single story buildings 2 Upstream Industrial 3,440,749 0.08 gpd/sqft Flow factor for Commercial/ Industrial land use Park Parcels ADWF 1 from 2012 Sewer Master Plan gpd Calculated flow (gpd/sqft* Building sqft) 275,260 0.275 mgd Calculated flow in mgd (included in model) Industrial Peaking factor for PDWF based on diurnal pattern 2 Park Parcels 1.45 - in model (10:00 am) 0.400 mgd Calculated PDWF (PF*ADWF) PDWF 1+2 Total ADWF 0.295 mgd Senior Center ADWF + Tributary ADWF 1+2 Total PDWF 0.426 mgd Senior Center PDWF + Tributary POWF RDll Loading 0.005 mgd Wet weather inflow in model for area tributary to 1+2 senior center 1+2 Total PWWF 0.431 mgd Total PDWF + RDII Loading Model 0.46 dID Maximum depth over diameter during PWWF 1+2 Results Note 1: Industrial flows originally in model based on 24% coverage. Flows were updated based on 50% coverage for this analysis. Table 3. El Fuerte Lift Station Capacity Check for Buildout Peak Wet Weather Flow Number from Figure Parameter Value Unit Explanation 1 Senior Center ADWF 0.020 mgd Calculated ADWF in mgd (from Table 1) 1 Senior Center PDWF 0.026 mgd Calculated PDWF in mgd (from Table 2) 2 Industrial Parcels Tributary to Senior 0.275 mgd Center ADWF Calculated ADWF in mgd (from Table 1) 2 Industrial Parcels Tributary to Senior 0.400 mgd Center PDWF Calculated PDWF in mgd (from Table 2) 3 Original Calculations for Industrial Park Parcels Upstream of LS Not Contributing to Senior Center Main ADWF 1 138 acres Buildout area contributing to El Fuerte LS (all Industrial Park except senior center) 24% Coverage Building footprint vs. land use area for single story building 43,560 sqft/acre Conversion acre to square feet 1,447,438 Building sqft Calculated building area for single story buildings 0.08 gpd/sqft Flow factor for Commercial/ Industrial land use from 2012 Sewer Master Plan 115,795 gpd Calculated flow (gpd/sqft* Building sqft) 0.116 mgd Calculated flow in mgd (included in model) 3 Updated Calculations for Industrial Park Parcels Upstream of IS Not Contributing to Senior Center Main ADWF 1 138 acres Buildout area contributing to El Fuerte IS (all Industrial Park except senior center) 50% Coverage Building footprint vs. land use area for single story building 43,560 sqft/acre Conversion acre to square feet 3,015,495 Building sqft Calculated building area for single story buildings 0.08 gpd/sqft Flow factor for Commercial/ Industrial land use from 2012 Sewer Master Plan 241,240 gpd Calculated flow (gpd/sqft Building sqft) 0.241 mgd Calculated flow in mgd (included in model) 3 Industrial Park Parcels PDWF 1.45 -- Peaking factor for PDWF based on diurnal pattern in model (10:00 am) 0.351 mgd Calculated PDWF (PF*ADWF) 1+2+3 Total ADWF 0.536 mgd Senior Center ADWF + Tributary ADWF 1+2+3 Total PDWF 0.776 mgd Senior Center PDWF + Tributary PDWF 1+2+3 RDII Loading 0.013 mgd Wet weather inflow in model for area tributary to El Fuerte IS 1+2 +3 Total PWWF 0.790 mgd Total PDWF + RDII Loading 1+2 +3 El Fuerte Lift Station 970 gpm Capacity of duty pump (IS also has identical standby pump) from 2012 Sewer Master Plan 1.40 mgd Capacity of duty pump in mgd Note 1: Industrial flows originally In model based on 24% coverage. Flows were updated based on 50% coverage for this analysis.