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HomeMy WebLinkAbout05/07/1991, C-3 - BRIDGE IMPROVEMENT PROJECT: LAGUNA GOLF COURSE AT NO. 2 TEE, CITY PLAN NO. P-23Y. MEETING DATE: ���m��►��III�� � U city of sa►n Luis oBispo MaV 7, 19 COUNCIL AGENDA REPORT ITEM NUMBER: I FROM: David F. Romero, Public Works DR-rector Wayne A. Peterson, City Engi Prepared by: John W. Hawley, pervising Civil Engineer J SUBJECT: Bridge Improvement Project: Laguna Golf Course at No. 2 Tee, City Plan No. P-23Y. RECOMMENDATION: By motion, approve plans and specifications for "Bridge Improvement Project: Laguna Golf Course at No. 2 Tee, City Plan No. P-23Y, " authorize soliciting of bids, and contract award by the CAO if the lowest responsible bid is within the Engineer's cost estimate. BACKGROUND: The existing timber footbridge located near Tee No. 2 at Prefumo Creek has deteriorated to the extent that it is in a potentially unsafe condition and beyond repair. Because of the level of deterioration and type of design, it is not economically or structurally feasible to rehabilitate the bridge, other than complete removal and replacement. It is also an obstruction to creek flows during heavy storms. It is proposed to remove the existing footbridge and construct a new arched timber bridge at a better location approximately 130 feet upstream. The new bridge is designed to accommodate pedestrians, mowers, and other maintenance vehicles and will convey 100-year storm flows. It will also provide a much needed and reliable vehicle connection between the northerly and southerly portions of the golf course. The only other vehicular crossing requires driving through the creek bottom via a concrete ramp. Hence during heavy flow conditions maintenance vehicles are required to drive through adjacent residential streets to access the southerly side of the golf course. The location for the new bridge was selected to facilitate the safest and most convenient crossing for both the golfers and vehicles. In accordance with a condition of the Initial Environmental Study, drought resistant erosion-control planting will be installed to enhance and protect the creek bank in those areas affected by the bridge removal and new construction. ALTERNATIVES: 1. Proiect as Designed (Pedestrian/Vehicular Bridge) . This project involves the construction of an arched timber bridge, 10- feet wide and 60-feet in length, the removal of the existing footbridge, and erosion-control planting. The utilization of glu-laminated beams and railings, rock facing on the concrete wingwalls, and new planting, is an C --- 3 � 1 111111111111001IN city of San LUIS OBISpo da COUNCIL AGENDA REPORT City Plan No. P-23Y Meeting of May 7, 1991 Page Two. attempt to provide an aesthetically pleasing bridge which blends with the natural terrain, yet is functional and durable. This project is estimated to cost $40, 000. This project locates the bridge in a safe, more convenient location, and will carry both golfers and golf course maintenance equipment. 2. Pre-fabricated Bridge (Pedestrian/Vehicular) In lieu of constructing a bridge on site, provide a pre-fabricated bridge structure which can be delivered to the site and installed. Pre- fabricated bridges are are generally constructed of steel or aluminum and are available in a limited number of designs. Their primary advantage is the simplicity of ordering and installing. Many can be purchased and installed in a very short time. A wood prefabricated bridge is usually not delivered in one piece. It requires assembly when it arrives. Our cost estimate assumes the Contractor will supply this kind of bridge. (Mission Plaza pedestrian bridge, while designed by us, is a pre-cut bridge. ) As in Alternative No. 1, the abutment footings and wingwalls would require normal construction, and the bridge removal and planting would also be included. This project is estimated to cost $37,000 to $40, 000. Time is not critical for this project. This project is similar to Alternative #1, and has no apparent advantage or disadvantage over it. 3. Bridge for Pedestrians Only. Designed to accommodate only pedestrians, the bridge width could be reduced to 6 feet, and the span to 50 feet (can be constructed lower down on the creek bank) . The structural components are therefore reduced in size. Considering the other aspects to be the same as Alternative No. 1 (i.e. , use of materials, planting, etc. ) , this project is estimated to cost $27, 000 to $30, 000. This alternative saves money to the detriment of the maintenance program. The low-water crossing of the creek will need to be maintained and access to portions of the course limited during periods of high-water flow. 4. Removal of the Existing Footbridge with City Forces (Modification of Either Alternative 1, 2 , or 3 . ) Removal of the existing footbridge involves demolition of the concrete abutments and the timber structure, disposal, and restoration of the creek bank. It is estimated that if City forces accomplished this work, it would reduce the cost of the project by approximately $1000 to $1500. C -3 - z 1111111111111�JlWflj city Of San LUIS OBIspo NiZ COUNCIL AGENDA REPORT City Plan No. P-23Y Meeting of May 7, 1991 Page Three. 5. Elimination of Aesthetic Features. The aesthetic features of the recommended bridge project are considered to be the arched glu-laminated beams and handrails, the rock facing on the wingwalls, and the planting. The glu-lam beams are a necessary structural component and were selected not only for their visual , appearance, but also because of the high strength characteristics and durability, and as such cannot be eliminated if a wood structure is to be used. The glu-lam handrail material costs are higher than standard lumber, but installation and maintenance costs are expected to be less. The rock facing improves the visual appearance of the concrete wingwalls, but is not structurally necessary. Elimination of this item would reduce the cost of the project by $1000 to $1500. Planting is a condition of the Environmental Study, and therefore a requirement of the project. This item is estimated to cost $1, 000. FISCAL IMPACT (Recommended Proiect) : Engineer's Estimate: $40, 000.00 Contingencies: 4. 000.00 Total Project Cost: $44, 000.00 The 1989/91 Financial Plan (Pg. E-11) designated $24, 000 for the replacement of the existing footbridge. Additional funding should come from the 1989/90 Capital Outlay CIP Control Account. The additional costs for the proposed bridge, which were not considered in the original estimate, are attributable to the increased width and span required to accommodate the maintenance vehicles, the removal and disposal of the existing footbridge, the erosion control planting, and aesthetic features. It is estimated that elimination of the aesthetic features and planting would reduce the cost by $2, 000. 00. CONCURRENCES: This project has been given a mitigated negative declaration and building permit by the Community Development Department. RECOMMENDATION: By motion, approve plans and specifications for "Bridge Improvement Project: Laguna Golf Course at No. 2 Tee, City Plan No. P-23Y, " authorize soliciting of bids, and contract award by the CAO if the lowest ' responsible bid is within the Engineer's cost estimate. Plans and Specifications are available in the Council office for review. 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