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Home My WebLink AboutCUP 99-30; Cannon Court; Conditional Use Permit (CUP) (12)I I I I I I • I I I I I I • I I I • I Hydrology and Hydraulic Calclations Cannon Court #210-010-38 MS xxxxxx Date: December 8,1999 Prepared for: West Development, Inc. Prepared by: O'Day Consultants, Inc. 5900 Pasteur Court Suit 100 Carlsbad, Califomia 92008 Prepared By: TG Checked By: MC N. Carroll I I TABLE OF CONTENTS Introduction/Methodology 1 Run-off Coefficients 2 Time of Concentration Nomograph 3 Intensity-Duration Chart/Isopluviab 5-7 Rational Method Calculations & Exhibits App. I I I INTRODUCTION The foUowing Hydrology study was prepared to support the Tentative Parcel Map/Site Development plan for Cannon Court APN# 210-010-38. EXISTING CONDITION Presently, the site is vacant and slopes gently from east to west. The site currently receives diainage fiom the parcel to the north, and a 24" RCP drainage outlet pipe @ the CalTrans right-of-way. The flow from the CalTrans pipe is conveyed across the property via a drainage swale and a shallow steel pipe. The entire site (and off-site contributing) drains to a 5'x 5' railroad tie culvert at the AT&SF raifroad. PROPOSED CONDITION The development plan proposes commercial/tourist site \^ch will cover most of the lot with buildings and A/C paving. The drainage will be connected to the existing outlet via a series of pipes/inlets as shown on the site plan (attached). HYDROLOGY Tlie run-off was calcualted using the rational method as outlined in the San Diego County Hydrology Manual. The following criteria was used: • lOO-year storm event • Time of concentration (Tc) calculated using appendix X-C (see page 3). • "C" values of .45 for existing, and .9 for proposed (see page 2). • Intensity "I" was calculated using the Intensity-duration Charts (see pages 5-7). RUiNGFF COEFFICIENTS (RATIONAL METHOD) LAND USE 80% Impervious Industrial (2) 90% Impervious Coefficient. C Soil Group (!) A B C D Undeveloped .30 .35 .40 EE Residential: 1 ii Sural .50 .33 .40 .45 Single Faaily .40 .45 .50 Multi-Units .45 .30 .60 . 70 Mobile Homes (2) .45 .50 •55 -.65 Counercial (2) .70 .75 .80 .35 .80 .85 90 JO .93 NOTES: (1) Obtain soil group from maps on file with the Oeparment of Sanitation and Flood. Control. (2) Where actual conditions deviate significantly fron the tabulated imperviousness values of 80% or 90%, the values given for coefficient C, may be revised by multiplying 80% or 90% by the ratio of actual imperviousness to the tabulated imperviousness. However, in no case shall the final coefficient be less than 0.50. For example: Consider ccmmercial property on D soil group. '^T:t\ml~iBqfier9io'us^^^ '~5Q% Tabulated imperviousness » 80% Revised C « |2. X 0.8S ' 0.S5 80 APPENDIX IX mmm ..£jc.ompJ4t-!- — ^eacf • Oi^tUnt//Tonr/Zne '/^ Aff/fe//es SAN DIEGO COUNTY DEPARTMENT OF SPECIAL OISTRICT SERVICES OESIGN MANUAL APPROVED ?'/ - xr-gi URBAN AREAS OVERLAND TIMI OF FLOW CURVES OATE '^/f/6f T APPENDIX ^FBUTSKO •l^ UTILITY DESIGN, INC. May 31, 2000 Planning Systems Dennis Cunningham 1530 Faraciay Ave #100 Carlsbad.Ca. 92009 Re: Cannon Court Dear Mr. Cunningham: Butsko Utility Design, Inc. has reviewed the above-mentioned site to determine if there is a potential to relocate the transmission corridor and substation. Based upon this preliminary analysis and information gathering, please find below a listing of existing utility constraints and what we believe to be the critical constraints, and summary. I. EXISTING UTILITY CONSTRAINTS 1. Encina Power Plant The Encina Power Plant provides the feed to the Cannon substation and the transmission corridor that extends east across Interstate 5. If the Encina Power Plant were to be relocated to the proposed site to the north, it is unlikely that the substation and transmission lines would be relocated from their present location. With the Agua Hedionda Lagoon on both sides of the proposed site, there is not an acceptable location for a new transmission corridor. The transmission lines would need to extend south from the proposed power plant location to the existing transmission corridor to maintain the alignment across Interstate 5. The Cannon substation would need to be within the alignment of the transmission corridor and accessible to the new power plant location. The relocation of the power plant would be contingent upon SDG&E being able to acquire the necessary private property, easements, permits, and satisfying state and local requirements for the realignment of the transmission corridor. 2. Cannon Substation Cannon substation currently occupies 160 feet by 275 feet (approximately). In order to relocate a substation, SDGE would require an acceptable alternative site location. The new site location would need to be accessible from the Encina Power Plant or the proposed location in order to maintain the feed to the Cannon substation. The relocation of the substation would have a significant impact on the existing 12KV distribution lines that leave the substation. There is an existing overhead and underground distribution line. These lines would need to be extended to maintain the circuits. State Highway and Railroad Permits would be required for any new highway and railroad crossing locations. The cost to relocate a substation is estimated at $10-15 million. This estimate is based upon historical data, but varies due to site-specific issues. 2. Transmission Lines There are multiple transmission lines that run east from the Encina Power Plant on the west side of the railroad tracks to the Cannon substation. The transmission corridor 17065 Via Del Campi) • Suirc 200 • SanDiego • CA • 92127 • S58.676.0700 • TAX 858.676.9771 XX'itll OKict.s m S.m Dle,^o ' Orani^e County • IIIIIUKI Hiiipire • Ccntr.il Coasi e Page 2 May 31, 2000 continues east from the Encina Power Plant, crosses the railroad tracks and the freeway. The width of the transmission easement is 400 feet. The location of the transmission corridor is dictated by the location of the Encina Power Plant, the ocean and the freeway. The relocation would be contingent upon SDGE being able to acquire the necessary easements and satisfying state and local requirements for the proposed route. According to SDG&E, relocation of the transmission lines would be virtually impossible unless the Encina Power Plant were to be relocated. Relocation of transmission poles is estimated at $200,000 per pole. 3. Overhead and Underground12l(v Distribution Lines There is an existing overhead distribution line that extends out of the Cannon substation on the north and continues east and west. There is an existing underground distribution line that extends south to Cannon Rd and continues east and west on Cannon Rd. Relocation of the substation would require the relocation of all distribution lines. The acquisition of new easements would be required for the new alignment as well as highway permits and railroad permits. The estimated cost for relocation of the distribution poles is $12,000 per pole. The estimated cost for relocation of the underground distribution system is $200.00 per foot. 5. Gas As a note, there is an existing 12" gas transmission line that runs north and south along the westerly property line. II. ADDITIONAL CONSTRAINTS 1. An Environmental impact report wiii be required per State of California, General Order 131D. The review and approval process historically takes 2-3 years. 2. Impact on the power grid, which is controlled by the power exchange. Any modifications would be subject to state approval and schedule. 3. Successful acquisition of private property for new corndor site. 4. Successful acquisition of all necessary easements. 4. Project Scheduie as it relates to the process schedule. 5. Costs 6. Subject to Coastal Commission review and approval In addition to our review, we contacted John Hernandez, Sempra Transmission Property Manager to discuss the project. John acknowledged that our assumptions were consistent with Sempra/SDG&E's position. In summary, we have found that the relocation of the Encina Power Plant, transmission corridor and the Cannon substation to be highly improbable based on the elements above. Should you have any questions, please do not hesitate to call Gregg Butsko or me at (858) 676-9700 ^IBUTSKO mm UTILITY DESIGN, INC. e Page 3 May 31, 2000 Or you may call to schedule a follow-up meeting to discuss these issues in more detail. Thank you for providing Butsko Utility Design with the opportunity to be of service. Sincerely, Martha Smith Project Manager Cc: John Hernandez Cc: John Buza I^IBUTSKO UTILITY DESIGN, INC. j-j- TTi^iTftTiniinJ-iiHi-oniuiaii.iiHiHiiHfg.-j . 1' I'l.ia.i if t-ma;fhri I Directions for Application: 1) From precipitation naps detennine 6 hr. and 24 hr. amounts for the selected freouency. These maps are printed In the County Hydrol Manual (10, SO and 100 yr. maps Included In Design and Procedure Manual). i) Adjust 6 hr. precipitation (If necessary) sol that It Is within the range of 45% to 65!li of] the 24 hr. precipitation. (Not applicable to Desert) 3) Plot 6 hr. precipitation on the rIgH side of the chart. 4) Draw a line through the point parallel to the plotted lines. 5) This line Is the Intensity-duration curve for the location being analyzed. Application Form: 0) Selected Frequency /^O yr. 1) Pg . I ia tn.. Pg^- 4.7> . \ • io±%* ?. 2) Adjusted *Pg- ^'^ 3) tg- win. 4) I • ,1n/hr. '24 In. *Not Applicable to Desert Region «nnD\inTV VT r A a. 30 t/1 2S -a o COUNTY OF SAM DIEGO OEPARTHENT OF SANITAjTION 6- FLOOU CONTROL 33' 30' 15 Prt|w U.S. DEPARTMEN I NATIONAL OCIiAMC AND SPECIAI. STUOieS BKANCII, OKFICii OF II 30* lOO-YEAR 24-H0l|R PRECIPITATION '-20^ISOPLUVIAL& OF 100 -VEAR 24-HOUn PRECIPITATION IN ENTHS OF AN INCH in* Jl*: • in I in • i Xf," V < n a. oo t/1 TJ m •z o X X COUfJTY OF SAN DIEGO j OEPARTMENT OF SANITATION S FLOOD CONTROL ! 33' 100-YEAR 8-HOUk PRECIPITATIOri ^lU ISOPLUVIALS OF 100-VEAR 6-HOUR PRECIPITATIOn ItJ TEimiS OF Ati IIJCII U.S. DEPARTMEN T OF COMMERCE NATIONAI. OCEANIC ANO ATujospilERIC AOMINISTIIATION SPECIAL STUDIES BRANCH, OmCC OF II 30 111* ICI we.* RATIONAL METHOD CALCULATIONS AND EXHIBITS I li I ICQ * '^K '^^V AieA *7.1 AO ^ t^l^ c^^o.iS' 4o t oveK/^vit? si^Tr u^>o-n> 'Af l='\']o' 0.45 (^^^^ C^^."^) * tc? ij^->:> 0Pf9T^ 1^ V-iiU. ll in - t - -1 .J 3 / 32 HYDROLOGY UAP BosmcoHomoM nYDROLOOiY MAP