Loading...
HomeMy WebLinkAbout11/20/2001, B-6 - TEMPORARY REPAIR/REPLACEMENT OF THE BRIDGE AT STENNER CREEK (AGENDA ITEM #7) `SETING AGENDA" { UMTE1L2D-�L ITEM# council mcmoRanbum ,city of san Lws osispo, Abmmist=ion dEpautmsnt DATE: November 13, 2001 TO: City Council Members FROM: Ken Hampian, City Administrative Officer SUBJECT: Temporary Repair/Replacement of the Bridge at Stenner Creek(Agenda Item#7) Staff is continuing to explore options for stabilizing the bridge on Foothill Boulevard. In order to pursue as many options as possible, staff will not be able to finalize the Agenda Report on this project and make it available to the Council until late in the day on Friday. Document/ Ma<uuq Detc council November 20, `01 j ac En as REpoRt 1� 46 CITY O F SAN L U I S O B I S P O UNCIL ❑ 000 DIR FROM: Michael D. McCluskey, Director of Public Works ❑ FIN DIR Prepared By: Barbara Lynch, Civil Engineer AO ❑ FI HIEF FATTORNEY IROPW DIR SUBJECT: FOOTHILL BRIDGE TEMPORARY CROSSINGCLERKIORIG ❑ POLICE CHF ❑ PT HEAD ❑ FRED DIR ❑ UTIL DIR CAO RECOMMENDATION ❑ HR DIR 1. In an amount not to exceed $260,000 total, authorize the CAO to (a) make a sole source rental of two temporary pre-fabricated bridges for two-way vehicle traffic from Bailey Bridge ($210,000); and (b) purchase a pedestrianibicycle bridge from either Steadfast or Continental Bridge based on delivery.timing($50,000). 2. Authorize the CAO to advertise for bids for a contractor to install (and subsequently remove) the three temporary bridges and authorize the CAO to award the contract if within the estimated cost of$150,000. 3. Authorize staff to advertise for bids to line the culvert inverts if permits and environmental clearance can be obtained and authorize the CAO to award the contract if the bids are within the estimated cost of$50,000. 4. To cover the costs of recommendations 1-3, allocate $460,000 in order to install culvert lining and temporary, pre-fabricated bridges where Foothill crosses Stenner Creek to be funded as follows: $50,000 from the Montalban Pedestrian Bridge Project account; and $410,000 from the unreserved General Fund balance. REPORT-IN-BRIEF After failure of the culverts on Foothill Blvd. at Stenner Creek in March, staff has monitored the area to determine if the culverts have stabilized or not. Review of recent data indicates they are continuing to settle, and staff believes more serious steps should be taken if Foothill Blvd. is to remain open until construction of a replacement bridge. Several options to maintain traffic on Foothill Blvd. were reviewed by staff. Options to stabilize the culverts are not guaranteed to work and some have permitting requirements and potential for polluting the creek. Staff believes installing temporary bridges to span the area, will provide for the safe movement of traffic without regard to the condition of the culverts. The cost is estimated to be $460,000 to purchase and install two vehicle bridges, one pedestrian bridge, line culverts and to complete necessary revisions to traffic control. DISCUSSION Background In March 2001, staff reported to the Council on the damage to the Foothill Bridge structure where it crosses Stenner Creek. The structure consists of two circular steel plate culverts. As the i V � Council Agenda Report—Foothill Bridge Page 2 Council may recall, this structure works via an interaction between the steel culverts and the backfill around them. Once either the steel or the backfill fails, it will compromise the other element. The end result is failure of the system. This is what has occurred at Foothill. State inspectors indicate there is a warning issued on these structures for the potential for brittle failure, sudden collapse. By March 2001, settlement had occurred in the street and the culverts had deformed. It appeared the failure was the result of the backfill around the culverts washing away over the years. Staff obtained Federal Highway Bridge Replacement and Rehabilitation (HBRR) funding for the replacement and received a commitment from the local Caltrans office to process this project in advance of all others for the District. The Council authorized the hiring of a consultant to begin the design for a replacement structure, and subsequently budgeted $950,000 for construction in the 2001-03 Financial Plan for its replacement: $190,000 from the General Fund and $760,000 in federal grant funds. Staff has continued to monitor the structure since the original settlement. Initially there was no additional settlement. Last month a comparison was made of roadway elevations taken over the summer. The comparison shows a very slow downward trend of the roadway. Staff made an investigation of the interior and noted some changes in the culvert since the initial failure in March. This means the structure is continuing to move. Status of Replacement Project Designers and environmental specialists have been hired and work is underway. There are several critical elements to the project. Cultural resources previously identified in the vicinity will require significant effort to determine the extent of those resources and ways to avoid or mitigate impacts to them. Several clearances and peinuts will have to be obtained from regulatory agencies. The City will also have to make a determination as to the desired hydraulic capacity of the bridge. The existing structure acts as a hydraulic constriction in the creek as do bridges downstream of Foothill. This design determination will be made after results of the hydraulic study are known and input received from the Zone 9 Creek Waterway Plan. After this decision, project design can proceed. The projected schedule shows all permits and environmental clearances complete by August 2002. Because of the permit requirements, this translates to a Summer 2003 start for construction. Interim Considerations (Or what do we do between now and the Summer 2003?) Originally, everyone was optimistic that the repairs could be accomplished during Summer 2002. However, as described above,numerous factors intervened and now that.timeframe is unlikely. The continuing movement of the culverts indicates they have not stabilized as originally hoped, but rather are continuing to deform. The likelihood they will survive until construction of the new culverts has lessened since the discovery of the continued movement. Therefore, interim solutions must be found. Foothill Boulevard, in the City's overall transportation circulation Y Council Agenda Report—Foothill Bridge Page 3 system, is a key link for pedestrians,buses and vehicles, and needs to be maintained as much as possible. Therefore staff has looked at two sets of interim measures: 1. Short term solutions until uninterrupted traffic flow can be guaranteed. 2. Mid term solution that allows traffic to flow regardless of the stability of the bridge. Short Term Solution Staff is planning full closure of Foothill, as authorized by the Council in March 2001, when heavy rain is predicted. Public Works has prepared a traffic control plan and is arranging for all necessary signing to be available for immediate closure if required Monitoring will occur after storms, in addition to the normal level of monitoring. The road will only be reopened if staff has determined that the culverts have not made a large shift during the storm. Thus, other than during times of heavy storms, conditions should pretty much remain as they appear today. Staff estimates that this solution will be needed until mid-January 2002. Mid-Term Solution Staff considered five mid-term solutions: 1. Construct a portion of the permanent replacement bridge over the culverts. 2. Line the invert(bottom) of the culverts with concrete to prevent further erosion of supporting soil. 3. Pressure grout the voids between the existing culverts to stabilize and stop further deterioration. 4. Implement a project that would repair and rebuild the culverts in place. 5. Install temporary bridges for two-way vehicle traffic and pedestrian/bicycle use. The following summarizes each of these options: Replacement Bridge. Staff considered building a portion of the new bridge, longer than necessary and spanning both culverts, to allow construction of some of the ultimate bridge this winter. However, building such a bridge would extend the bridge support structure farther out of the area of the old creek that was filled around the culverts and farther into the old creek bank. This increases the potential,disturbance to cultural resources. Obtaining clearances to work in the area because of the presence of cultural resources will take as long or longer than obtaining permits for working in the creek. It did not appear trying to stay out of the creek and building the bridge would result in earlier construction. This idea had merit because any portion of an ultimate structure would be eligible for 80% Federal reimbursement. All temporary costs must be borne by the City. However, this idea was dropped due to length of time necessary to get permits. Council Agenda Report—Foothill Bridge Page 4 Concrete Lining. Staff also initially considered extending the headwall deeper, thinking possibly the water was coming under the headwall in heavy storms and washing away the backfill from around the culverts. Since March 2001, the water in the culverts has dropped considerably; and it is obvious the bottom of the culverts has rusted through in many places and the backfill has many places to migrate from between the pipes. The design consultant suggested that the two bottoms be paved with a foot of concrete in the interim to seal the damaged bottom. This strategy will require a permit from the Army Corps of Engineers after consultation with the National Marine Fisheries Service. It could be considered a significant impediment to fish passage, resulting in denial of such a plan. Staff is looking at a modification of this concept, using shotcrete (sprayed on concrete) to mimic the contours of the culvert, while still sealing off the holes in the bottom. Initial estimates indicate this would cost approximately $50,000. There would still be permits to be obtained, and while there are opportunities for emergency consultations with the regulating agencies, the total time to get the permits and environmental clearances is unknown. Staff believes this option is still worth pursuing, in an effort to keep the culverts from collapsing and causing flood damage. Pressure Grout. The third idea was to pressure grout around the culverts to compensate for the lack of backfill. Pressure grout is typically a very fluid material, designed to flow readily to penetrate and fill voids. Unfortunately with the number of voids visible in the culverts (like the bottom is missing in some places) and the likelihood of small, unobserved holes, there is a high (almost guaranteed) possibility for a grouting operation to spill.grout into and pollute the creek. This idea was dropped due to the unknown cost and possibility of grout polluting the creek. In-Place Culvert Rebuild. Another idea raised after the settlement in March 2001 was the possibility the culverts could be rebuilt in-place. This idea was also suggested to the Council at its last meeting by former Council Member Dave Romero. Staff posed the question to the Caltrans Division of Structures Senior Bridge Engineer, who came to inspect the culverts. He indicated that the culverts, in their destabilized condition, would not survive the excavation. It would be impossible to evenly unload the material over the culverts so as not to aggravate their condition and cause them to collapse. An estimated one-quarter to one-third of the culvert plates are rusted through and would have to be replaced. Virtually all the plates exhibit some sign of distortion. The culverts had a 20-year life when they were built in 1964. Such an undertaking would require a substantial number of plate replacements as well as permits to work in the stream to disassemble and replace those plates. Repairs would not be eligible for reimbursement from the HBRR program. The time line would be virtually the same for construction. For nearly the same level of effort, we can construct a'bridge of a considerably longer life, with 80% Federal funding. The time line shows this is not an interim solution, but rather an alternate to complete replacement with a typical bridge structure. There are too many advantages of a typical bridge structure, such as restoring a native creek bottom, extended service life and funding assistance,to proceed with a major maintenance project on this structure. Temporary, Pre-Fabricated Bridge. Because none of the ideas studied appeared to either be feasible or quickly implemented, staff considered a temporary, pre-fabricated bridge option. A Council Agenda Report–Foothill Bridge Page 5 temporary bridge would be placed above the roadway rather than at grade with the roadway. There are four main advantages to this approach: 1. Cultural resources will not be an issue,because very little excavation would be needed. 2. A temporary bridge will keep traffic off the damaged structure—easing the load on it; and it will provide for continuous traffic through the next two winters without risk to the public should the culverts collapse. 3. No work will take place in the creek; therefore, no Army Corp or National Marine Fisheries permits will be required. 4. The transportation corridor will be maintained indefinitely until a permanent replacement is constructed. Staff evaluated how many bridges were needed and what was available in the industry. Staff contacted Bailey Bridge company, which has a good product reputation and is located in San Luis Obispo to find out what would be available and at what cost. Bridge Requirements Two vehicle bridges would be required, one for each direction of traffic on Foothill, as each bridge has a clear width of only 11 feet. The bridge supplier recommends a separate structure, such as the one installed for the Jennifer Street Bridge project, to handle pedestrians. The three bridges would be placed approximately where the traffic now runs, and a width of about 3.0 meters (10 feet) will be maintained to the side to allow access to driveways close to the creek. The road is currently operating with two lanes for vehicle traffic along with sidewalks and bike traffic. Rental Versus Purchase The City has the options of buying or renting the vehicle bridges. For the period of about 18 months that we currently anticipate needing the structures, the cost is about$20,000 less to rent. The staff recommendation is to rent two temporary bridges, rather than buy them, after considering what would happen when the bridges are no longer needed. A suitable storage location would be needed along with adequate monitoring of the bridge components over time to ensure continued reliability, with no guarantee that we would be able to reuse it in the future. The City could also attempt to sell the bridges,but the resale value is unknown. The advantages to renting are the company's location in San Luis Obispo and their stock of bridge components. If the need arose for a temporary bridge in the future, we expect that it could be rented in a timely manner. The proposed pedestrian/bicycle bridge would be purchased for temporary use on Foothill. When it is no longer needed, it would be moved to a permanent location on Montalban Street, where the Council has approved installation of a pedestrian/bicycle bridge across Stenner Creek (2001-05 Capital Improvement Plan,page 230). Council Agenda Report—Foothill Bridge Page 6 Recommendation Because of the need to minimize the risk of a culvert collapse closing the road, staff recommends authorizing the CAO to make single-source rental for the two temporary bridge rentals from Bailey Bridge and the pedestrian bridge purchase from either Steadfast Bridge or Continental Bridge based upon time of delivery criteria. Section 204 of the Financial Management Manual provides single-source purchasing when the vendor has one-of-a-kind product or service that the City desires to use. The bridge suppliers do not offer installation services, so a qualified contractor must be hired to perform the installation, which includes the transition ramps on and off the bridges, traffic control and signing and striping to complete the work FISCAL IMPACT Project Cost As summarized below, estimated costs for purchasing, installing and removing the three temporary bridges and lining the culverts is $460,000: Renting two (2) temporary vehicle bridges (provides for one lane each way) 210,000 Purchasing one (1) pedestrianibicycle bridge 50,000 Installing and removing the three bridges 150,000 Culvert lining 50,000 Total $460,000 Funding Sources An initial review of possible funding sources indicates that it is unlikely that there will be any outside funding for this temporary project. For example, interim stabilization or temporary structures are not eligible for HBRR funding. Disaster relief funding for this project is also unlikely, since the storm that revealed (or perhaps precipitated) the damage was not declared an emergency, and the bridge has not yet failed, making funding for "prospective" interim repairs from the Federal Emergency Management Agency(FEMA) unlikely as well.. We will continue investigating the possibility of outside funding for the proposed temporary solution; however, in the interim,we recommend funding this project as follows: Pedestrian-Bicycle Bridge. As noted above, we recommend relocating the pedestrian bridge to Montalban where it crosses Stenner Creek once it is no longer needed at Foothill. Accordingly, we propose funding its purchase (estimated at $50,000) from the Montalban pedestrian-bicycle bridge project. The 2001-05 Capital Improvement Plan allocates $187,000 for this project: $37,000 for study and design in 2001-02; and $150,000 for construction in 2002-03. This project is funded from two sources: $67,000 in transportation impact fees and $120,000 in State grants. Although we have not yet confirmed that this purchase will be grant eligible, we believe that it is likely to be. However, we will not be able to draw down fund for the purchase of this bridge until it is relocated to Montalban. Council Agenda Report–Foothill Bridge Page 7 Vehicle Bridges and Culvert Lining. As noted above, we have not identified any outside funding sources for this project. As such, we recommend appropriating $410,000 from the unreserved General Fund balance. Based on interim results for 2000-01—where ending fund balance was about $1.6 million better than projected—this added appropriation will result in an ending fund balance that is still significantly in excess of our policy minimum of 20% of operating expenditures. However, we should not let this lull us into a false sense of security about our fiscal outlook. Even before the tragic events of September 11, we were concerned about our fiscal outlook in light of a softening economy. These concerns have intensified since then for two reasons: 1. Uncertain fiscal impact of the tragic events of September 11, especially on key, revenues like sales tax and transient occupancy tax. 2. Potential impact of State budget grabs from cities as it deals with its own real budget problems. At this time, a State budget gap of$5 to $15 billion is estimated for 2002-03. The "VLF backfill," under which the State makes cities and counties `whole" for the vehicle license fee (VLF) reduction of 67.5%, costs the State General Fund almost $4 billion annually. This makes it a possible target as the State begins crafting its budget solution. For the City, VLF is our fifth largest revenue source, and is projected to bring in $2.4 million in 2001-02. Of this amount, $1.6 million comes from the VLF backfill. If the State takes away the VLF backfill (which would be consistent with its budget grabs from cities in the mid- 1990s), this loss would have profound impacts on the City's ability to fund essential services. Given these uncertainties, we do not recommend using the unreserved General Fund balance lightly. And because of this, we will be working diligently on identifying other external and internal sources of funding for this project between now and the mid-year budget review. In the interim, however, we believe that the General Fund unreserved fund balance is an appropriate funding source for this important project- in fact, it is the kind of unforeseen circumstance that our minimum fund policy is indicated to mitigate. And fortunately, because of favorable ending results for the past fiscal year; we will be able to fund this project and still retain the General Fund balance at more than its minimum policy level. ALTERNATIVES 1. Do nothing and continue to allow traffic to use Foothill. With this option, we would close the street in advance of heavy rain and monitor the bridge for significant movement. The bridge would also be subject to permanent closure in the event of significant movement or collapse. This will have continued impacts to traffic patterns through reduced lanes as well as significant impacts to traffic when closures are made. It carries some element of risk, as the structure is not predictable. This has minimal fiscal impact and could be the cheapest solution. The actions recommended above could be employed if the bridge did collapse. However, there is the risk that lives could be endangered; and transportation circulation would be a mess until the Foothill link was re-established. Council Agenda Report—Foothill Bridge Page 8 2. Authorize culvert lining and authorize installation of temporary bridges but delay that implementation until actual failure. If the lining is successful in stopping additional failure, expenditure of funds for the temporary bridges may not be necessary. The same risks as above would still exist but response timing would be about 30 days quicker due to pre- authorization. Six weeks would be the most likely time frame for installation — four weeks for delivery of bridge parts and two weeks for erection and installation. Staff would immediately bid the project and the contract would be awarded with a contractor ready to perform the work when the bridge parts arrived. The pedestrian bridge would take another month to arrive. This could save approximately $410,000 if everything went as hoped for the 18 month period. It would also be possible, if the structure collapsed, for the City Administrator, in conjunction with the City Council, to allow City crews to install the bridges under an emergency condition. If the City Council opts to proceed with this alternative, staff recommends the City Council, at this meeting, authorize the City Administrator to proceed immediately upon culvert collapse, with Council declaration of the emergency to follow at the next regularly scheduled meeting. 3. Modify Alternative 2 to authorize the rental of temporary bridges now. This would decrease the amount of time that the road would be out of service by four weeks but would likewise mean the expenditure of funds for the temporary bridges whether or not they are put into use. 4. Close Foothill at the bridge at this time and route traffic around the area. This will have a significant impact to traffic patterns. Traffic routing around to the south will impact Murray and Casa in the vicinity of the hospital, an area that is already very congested. This will occur during temporary closures with Alternative 1 as well. 5. Pursue one of the other mid term solutions. There will be consultation with regulatory agencies and permits required. Success in stabilizing is not guaranteed. Some of the options have the potential of polluting Stenner Creek. Lastly, these options become more difficult to implement as we move into winter. g:\mmmt projects\bridges\90197 foothill_stenner\_staff reports\90197b temp br.doc