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HomeMy WebLinkAboutAgenda Statement 1977/04/19 Item 10CITY OF CHULA'VISTA ITEM N0. 10 COUNCIL AGENDA STATEMENT ~ '~ ~~ 4/19/77 FOR MEETING OF: ITEM TITLE: Resolution 8586: Accepting Work by Wilsey & Ham for Preparation of Conceptual Plans for Telegraph Canyon Road and Channel and Setting a Public Haring for Alignment Adoption ,, SUBMITTED BY~ Director of Public Works/City Engineer ~J~~ I" I ITEM EXPLANATION ~" By Resolution No. 7345, the City Council approved an agreement with Wilsey & Ham for the preparation of conceptual plans for Telegraph Canyon Road and Channel. The terms of the agreement have been fulfilled by Wilsey & Ham. The staff has reviewed the work and finds it to be satisfactory. Attached is the Design Report and Executive Summary for the project as prepared by the consulting engineer. The conceptual plans are on file in the Department of Public Works. Mr. James A. Hutchison, Project Engineer for Wilsey & Ham, will make an oral presentation at the Council meeting describing the work that was accomplished. This Resolution merely accepts the work accomplished by Wilsey & Ham and authorizes that they be paid in accordance with the terms of their con- tract. This action does not adopt a precise alignment. In accordance with Resolution No. 6655 (Council policy requiring public hearing prior to road widening projects) this Resolution will set the date of May 17, 1977 for a public hearing, which testimony will be used to determine the final specific alignment for Telegraph Canyon Road. The Planning Com- mission on February 23, 1977 held a public hearing for the adoption of the Environmental Impact Report and this report will be distributed to your body prior to the alignment hearing. r\/I II 1"11 Tf1 ATTA/~1 Irf1 C1CI'11CSI I J F~11 I Hl.l"iCU Agreement Resolution X Ordinance Plat Other X 1) Design Rpt Environmental Document; Attached Submitted on 2 ) Executive j Summary STAFF RECOMMENDATION: Approve Resolution accepting the work of Wilsey & Ham for preparation of conceptual plans for Telegraph Canyon Road & Channel and setting May 17, 1977 for a public hearing for consideration of final alignment for Tele- graph Canyon Road between Crest/Oleander and the easterly City limits. BOARD/ COMMISSION RECOMMENDATION COUNCIL ACTION apP~OV~D by the City Council of Chula Vista, California Dated, ......~'•~y~• ~ 7.....~..,.w~ Form A-113 (Rev. 5-75) 112-01 March,. 1 X77 , DESIGN REPORT TELEGRAPH CANYON ROAD AND CHANNEL EXECUTIVE SUMMARY INTRODUCTION The Program In order to permit the logical and orderly development of properties adjacent to Telegraph Canyon, it was the City's desire to have con- ceptual plans prepared. The plans detail the concept for the coor- dinated development of Telegraph Canyon Road, sewer, and drainage facilities. The limits of work on Telegraph Canyon Road are from Crest Drive (near I-805 freeway) on the west to approximately 3.3 miles east at the existing county box culvert crossing Otay Lakes Road just east of Rutgers Avenue. Authorization By Resolution No. 7345, the City Council of the City of Chula Vista approved an agreement between the City and Wilsey ~ Ham for preparation of conceptual plans for Telegraph Canyon Road and Channel. Scope of Work Development of the concept plan was done in phases, which are described in the agreement between Wilsey ~ Ham and the City of Chula Vista. The various items of work are listed below: 1. Preliminary Phase a. Review base material and requirements of City and other agencies b. Prepare 100 scale aerial photogrammetry c. Prepare alternative preliminary engineering studies d. Prepare computerized hydrology study 2. Plan Preparation and Conceptual Design Phase a. Prepare plans at scale of one inch equals 100 feet horizontally and 10 feet vertically b. Delineate centerline of sewer, utilities, highway and major drains c. Propose grades for Telegraph Canyon Road d. Propose flowline grades for drainage channel and road crossing structures e. Indicate sanitary sewer grade f. Detail typical sections of drainage channel at various locations g. Delineate design considerations for major drainage structures -2- h. Designate areas requiring additional erosion protection i. Delineate approximate right-of-way lines j. Indicate approximate limits of cut and fill required 3. Preliminary Cost Estimate 4. Project Report Previous Construction The existing alignment of Telegraph Canyon Road along approximately two miles of the study area east of Brandywine Ave. was established by the County of San Diego on Road Survey Number 1086-65• Construction according to County plans was completed in February 1967• Pavement width between asphalt dikes is 40 feet centered within the right-of- way. A three foot shoulder widening on the north was included for approximately 4,575 feet. The 1867 construction included a trapezoidal channel where the existing channel was adjacent to the road (2,490 feet). The bottom width of the channel was to be a minimum of 10 feet. This channel had 24 inches of rock facing on the slope adjacent to the roadway. Between 1958 and 1962, construction in Telegraph Canyon was performed in accordance with the alignment and plans developed by the County of San Diego as Road Survey 1086. Generally this consisted of 36 foot wide section. The trapezoidal channel where adjacent to the road was constructed with a minimum of 5 foot bottom width. Plans for the intersection withOtay Lakes Road were developed in 1964 by the County and shown on Road Survey 558-64. Widening near Buena Vista Way was done in accordance with Chula Vista City Plans for El Rancho del Rey, Unit No. 1. Preliminary plans have been processed by the City for improvement of Telegraph Canyon Road adjacent to the proposed Canyon Townhouses near Crest Ave. Roadway construction is underway adjacent to Windsor Views. Previous Studies In 1864, a Special Study of Storm Drainage Facilities was prepared as a supplement to the Chula Vista General Plan. This study included run- off calculations for Telegraph Canyon beginning at its upstream limit and extending to the bay. CalTrans has also studied drainage of Telegraph Canyon in reference to construction of freeway crossings. Hydrology studies of Telegraph Canyon were also conducted by the Corps of Engineers in 1974. -3- A report on the collection, treatment and disposal of sewage and industrial wastes in the City of Chula Vista, including the Telegraph Canyon basin, was prepared in 1959• A trunk sewer was constructed in Telegraph Canyon Road based on plans prepared in 1961. FINDINGS Alignment The original alignment of Telegraph Canyon Road was developed by San Diego County prior to annexation of the facility to the City of Chula Vista. In general, the road follows the canyon floor to avoid the naturally rugged terrain of the East Chula Vista area. The proposed alignment re- mains subject to the same topographic constraints, however, it is planned to increase the radius of many of the curves. The first curve near Crest Drive is designed for a speed of 45 miles per hour, the next curve easterly at 55 and the remainder for 65 miles per hour. Alignment changes are proposed from 1,200 to 2,600 feet easterly of Crest Drive (near E1 Rancho del Rey Unit 5). The existing right-of-way traverses a sharp (750 foot radius curve) and a short section of tangent. If the new construction followed this alignment, the design speed would be compromised. To avoid this consequence, the proposed alignment follows a straight course through this section, deviating considerably from the existing right-of-way. Hydrology A hydrologic analysis of the entire basin was performed using a modified Rational Computer Program. Both present and ultimate quantities of runoff from a 50 year period of frequency storm were estimated and compared with estimates by the Lawrence, Fogg & Smith study in 1964 and the recent Corps of Engineers study. After considerable study, it was determined to base the flood channel desiyn on the Lawrence, Fogg S Smith study which balanced a Higher estimate by Wilsey ~ Ilam and a lower estimate by the Corps of Engineers. This will also provide continuity with existing facilities downstream. The following design flows will be used for Telegraph Canyon Channel upstream of the noted streets: Crest Drive 2,850 cubic feet per second Brandywine Avenue 2,600 " " Buena Vista Way 2,100 " " " Rutgers Avenue 1,600 " " -4- Channel Design A large variety of possible shapes, sizes, linings and slopes were hydraulically analyzed to identify suitability of each for use in con- junction with the Telegraph Canyon Road project. A number of physical constraints affect the shape and configuration of the ultimate channel. For example, if the depth of the channel exceeds or approaches the depth of the existing 15" VCP trunk sewer, future gravity flow sewer mains are affected and lift stations or inverted siphons may be required. Con- sequently, the ultimate channel should not exceed a depth of eight feet at expected sewer crossings (six feet depth of flow plus two feet freeboard). Extremely wide channels would require excessive right-of-way requirements and generation of high cut slopes. The existing gradient (1.0 to 1.5%) results in erodible velocities for unlined or poorly lined channels, thus restricting the types of linings which can be used or requiring the use of periodic drop structures. Telegraph Canyon Road is designated as a scenic road. As such, extra care should be taken in the design of a flood channel, to avoid detracting from the scenic qualities of the area and, if feasible, to improve the views. It was the specific desires of the Chula Vista City Council that a grassy or landscaped, "natural" appearing channel be considered. Because of the restricted width of the canyon floor and the existing urban development there, it was the feeling of the City Engineering staff that the westerly 2,500 feet would have to be developed with a lined channel. Alternate Flood Channel Sections For evaluation of their effectiveness in controlling the storm flows, meeting a majority of the other constraints and for comparing from a cost standpoint, the follo-~ing storm drain sections were evaluated: 1. Trapezoidal Channel - with grassy lining 2. Trapezoidal Channel - with heavy landscaping 3. Trapezoidal Channel - with maintenance road, low flow channel and grassy lining 4. Trapezoidal Channel - with rip-rap on side adjacent to highway 5. Trapezoidal Channel - withgunite lining 6. Rectangular Concrete Channel 7. Multi Plate Super Span 8. Multi Pipe 9. Reinforced Concrete Box Evaluation of Channel Sections The channel types were compared using the same hydraulic capacity for total costs of construction, maintenance and right-of-way. A trape- zoidal channel with heavy landscaping proved to be the most cost effec- tive design and is recommended for the majority of the project. The most westerly 2,770 feet of Telegraph Canyon is quite narrow, especially considering the widening of the highway. Because of the restriction; the westerly portion is now planned as an open trapezoidal channel with gunite lining except at roadcrossing and a reach crossing the toe of a steep slope. -5- Road crossings will require a bridge or enclosed section such as a double or triple reinforced concrete box. Approximately 1,800 feet easterly of Crest, a rectangular channel or enclosed section is re- commended to avoid extensive excavation of a hill on the north. Wherever intensive land use development is planned adjacent to the road, closed conduits maybe justified to avoid narrow, inefficient building sites. Preliminary Cost Estimate The channel construction is estimated to cost $1,475,000 based on 1976 costs. This includes excavation, lining, relocation of interfering utilities and temporary buildings as well as construction of five road crossings. The highway construction is estimated to cost approximately $90.00 per lineal foot or $1,775,000 based on 1976 costs. This includes excavation, curb, gutter, sidewalk, bikeway, new pavement on one side, reconstruction and resurfacing where existing pavement is utilized in the design, planting and irrigation of the median, but excludes right of way. COIJCLUS I ONS 1. Telegraph Canyon Road easterly of Crest Drive is too narrow and the alignment is inadequate to facilitate the traffic expected with proposed development in the eastern area of Chula Vista. 2. The channel adjacent to Telegraph Canyon Road in the same area is subject to flooding and will not contain the projected storm flows without flooding the adjacent property and street. 3. Because Telegraph Canyon Road is a scenic route, the construction of the road and channel should conform to requirements for scenic routes. 4. Development of a conceptual plan indicating acceptable types of channels, road sections, alignment and grades is necessary to allow coordination of expected phased construction of these im- provements. 5. The alignment of the road must reflect the constraints of existing improvements and topography. 6. Continued use of two channel types can best meet the goals of carrying the design flow, aesthetics, and low construction and maintenance costs while still not precluding the development of adjacent properties. -~- 7. Channel crossings should normally b~. enclosed sections with transition sections upstream and downstream. Their design should allow for construction of all normal utility crossings. The transition structures should be designed to avoid erosive velocities in the unlined channel portions RECOMMENDATIONS 1. Formalize the highway alignment ("N-Line") shown on the plans through preparation of a Record of Survey and a right-of-way map. 2. Adopt the "N-line" alignment through formal action by the City Council. 3. Designate and use the design flows for Telegraph Canyon Creek as developed in the 1964 Fogg Study of Storm Drainage Facilities for future design of flood control facilities in Telegraph Canyon. 4. Designate the gunite lined, open channel trapezoidal section (Exhibit 4-2) to be used (except where property owners desire to install an enclosed section) in that segment between Crest Drive and 2,770 feet easterly. 5. Designate the open channel trapezoidal section with heavy land- scaping (Exhibit 4-1) to be generally used from 2,770 feet easterly of Crest Drive easterly to the end of the project (near Rutgers Avenue) 6. 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TiP~4PEZ0lQ4L C~/QNNEL- `V/T!,/ GRASSY L/N/NCB 2. TR~G°EZO/A/J[ CI~ANNEL - W/TL1 ~/EAI/V LANOSC.4P/NG ~ 24 ` IOC G' 2 ~ 5'- 20' 32' ~s~I,4/NT, R , _ _ -~_~ `~ ~ , 1 ~~ 6 6qB ~ ~ d l 4 4 a a, 3' /' r 3. TR,4PEZ0/aWWL C<1,4NMEG -WITH iYIA/NTEN•4NCE' .4L140 LOW FLDyV C,c/gNNEL A/YD GRgSS L/N/NG, AL TE,r?/VATE STDRM ORA/N SEC T/ONS /lo ~ 2 Ql 25'-52' 8~ 2 0~ 3 32' ~~ s ,./,~ ~ TQgPEZO/AAL C~/ANNEL -1N/Tip/ R/P-RAP Oy1/ QuVE S/DE ~`f,/EAVY L"4NOSCAP/NG O/V REMA/NOE~2 2 ~/ ~~ - /- ~ -. B' /lo' /2 ' -2 - o, e o ~e . e /~° ..... • /D~ HlA/NT. ,~7AD 5: TRAPEZOIDAL Ct/ANNEL - l~V/TN G!J/V/TE L/N/NG (A,BM~ x X /O "- 20' 2 ~ y auoo~ r /~ ~~~ 8~ ' A/NT. ~2 4 ~. RECTANGULAR coNGQETE Gy,4NNEG ~ ' EXf~/B/T 4 $ • ALTERNATE STORM DRA/N SECT/ONS • 3 Q ~' 3 Z5" 2.5" 2.5~ 2•~ o 20'- 27~ ~`9 .. •e; 3 ` 3' 7, MUL T/-PLATE SUPER SPAN o~oo $. MUL T/ - P/PE ~8"TO /2" TN/CK WALLS 9, .4E/NFORCED CONC,4ETE BO.t!