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HomeMy WebLinkAbout12/02/2008, SS2 - 2008-09 CITYWIDE WINTER WEATHER PREPARATION counat December 2, 2008 j acEnda Report he. CITY OF SAN LUIS OBISPO FROM: Jay D. Walter, Director of Public Works & Shelly Stanwyck, Assistant City Manager Prepared By: Barbara Lynch, City Engineer & Neil Havlik,Natural Resource Manager SUBJECT: 2008-09 CITYWIDE WINTER WEATHER PREPARATION CAO RECOMMENDATION Receive and file a report on the City's 2008-09 winter weather preparations. DISCUSSION Background Each year, to prepare the City creeks and storm drains for winter, City staff complete a variety of activities. By preparing for wet weather the risk of flooding in the community is greatly reduced. The work has traditionally been carred out by City Administration and Public Works staff, with assistance from the Utilities Department, the California Conservation Corps, and the occasional herd of goats or sheep. Throughout the year staff thins vegetation, removes blockages, responds to community identified concerns, and monitors various locations. This year, in conjunction with the City's new Stormwater Program, Utilities Department staff members have augmented these existing efforts through the implementation of the new and expanded storm drain cleaning operations. The Mayor has expressed an interest to the staff in providing an annual report to the community on the City's winter weather preparations. If the Council finds this report productive, staff can plan to make similar presentations in the future. During the Council Meeting of December 2, staff will make a visual presentation of much of what is summarized below. 2008-09 Creek Winterization 1. Rock Guards Throughout the City there are about 15 rock guards. These "pipe grate" structures are typically placed near the entrance of a culvert that accepts drainage from the steeply sloped hills around town. Their purpose is to prevent large material and debris (rocks, branches, etc.) from entering the culvert, becoming lodged in place, and creating a storm water back-up that cannot be easily removed. Based on the important functional role they play, the City routinely inspects and maintains its rock guards. In preparation for the upcoming winter season, City Public Works staff has checked and cleared all City rock guards. As a result of previous flooding experience, minor modifications have been made to the rock guard above Andrews and Conejo streets to C�- - I I 2008-09 Winter Prep Page 2 reduce the likelihood of clogging. The bar spacing was increased upon the recommendation of the consultant working with the City on a reconstruction of that stormdrain entrance. The staff has also inspected and cleaned all the known "hot spots", which are those locations that tend to have flooding problems. Material, typically vegetation and rocks, can collect during the year which will affect the efficiency of these facilities. In conjunction with the rock guard maintenance this year three major culverts were also cleaned: the culvert at the east end of the City portion of Prado Road; the culvert at Exposition Drive below South Street; and the culvert along the south side of Foothill Boulevard at Cuesta Drive. 2. Creek Work Each summer City Natural Resource staff inspect the main creeks in the City (San Luis Obispo, Stenner, Prefumo, Brizziolara, Old Garden, and Acacia Creeks) to determine the scope of work for debris removal, complete vegetation thinning, and to assess other"winterization"needs in the creeks. During the 2008 creek inspections, staff found that the two large storms from 2007 generated a significant amount of debris, most likely because the year before had not yielded any major storms at all, and hence very little movement of material. As a result, several areas along San Luis Obispo Creek, Prefumo Creek, and Acacia Creek were found to need special attention. Also the outlet at Laguna Lake needed cleaning. These projects were completed in September and October, after some earlier work using California Conservation Corps crews in late July and early August for debris-jam cleaning and removal. In November some final work was done using goats to clear several large accumulations of herbaceous material in the floodways that are attractive to the goats, mainly Cape-ivy (Senecio), and sweet clover (Melilotus). This work was done at the lower end of the Water Reclamation Facility (WRF) and in a former homeless encampment area along San Luis Obispo Creek below Los Osos Valley Road. Prefumo Creek received a lot of attention during 2008. Thinning and removal of both live and dead material along Prefumo Creek at Calle Joaquin was undertaken in an effort to improve storm flow characteristics there and to provide some improvement of the visibility of the former Denny's restaurant, now known as Zaki's Golden Waffle Shop. Another area along Prefumo Creek upstream of Laguna Lake (the so-called "Prefumo Arm" of Laguna Lake) was cleared of numerous fallen willows that had occurred since last year. At least twenty such trees were cut out of the creek channel itself, and goats were used to create an easier flow line for storm flows. Finally, as noted above, the outlet of Laguna Lake had the debris "dam" breached to lower the elevation at which Laguna Lake begins to spill by about one foot. This was an interesting project requiring a small excavator and about a dozen CCC members using wheelbarrows as a shuttle to get the removed debris out of the creek channel and into dumpsters for disposal. Several other areas that received attention were on smaller streams such as Old Garden Creek at Broad Street, Orcutt Creek at Sacramento Drive, Islay Creek at Rosemary Park near Poinsettia Drive, and the several small creeks at the Tumbling Waters development on Orcutt Road. 2008-09 Winter Prep Page 3 3. Multi-Agency, Multi-Department Efforts to Minimize the Impacts of Homeless Encampments on the Creeks. For many months, City staff, led by Administration and assisted by several departments has been working to remedy the impact to the creeks of homeless encampments. There are several throughout the City where the adjacency to the creeks have created significant impacts. The accumulation of trash and human generated debris is a constant component of creek clean-up days and from a creek health standpoint, an issue that needs to be dealt with on several different levels. Staff has formed a task force representing the following programs or agencies: City Administration, City Natural Resources (including the Biologist), City Stormwater, City Code Enforcement, Water Reclamation Facility (WRF) lab staff, City Rangers, Police, Department of Fish and Game, Regional Water Quality Control Board (RWQCB), and County EOC staff. The intent is to develop a holistic approach and ensure our goals are in concert with the programs in place and under development with the County of San Luis Obispo. Once homeless camps have been vacated, a contract cleaner comes in and removes all debris to prevent further contamination of the creek systems. Educational literature is being developed to be distributed to both the homeless and the private property owners who happen to have camps on their property with information about mandates and enforcement actions that could be taken if this debris is carried to the creeks during winter storms. Progress is being made on all fronts but this is a long term project that will require ongoing staff time and resources to find a viable solution. Stormdrain Cleaning As part of the City's enhanced Storm Water program additional work on the storm drain system has been accomplished in preparation for this winter. Using the recently arrived hydro-cleaning machine, staff has cleaned 625 of the City's 1111 drainage inlets and removed approximately 27 tons of debris. This work ensures the drainage inlets are not plugged which would prevent water from entering the system, reduces flooding potential, and free from debris which would have been flushed into the creek system. Capital Improvement Projects Several roadway improvement projects have been completed in the last 12 months that have improvement the streets ability to convey flood waters. The Santa Barbara Widening project added three new drainage inlets, three new storm drain manholes and installed 472 feet of new drainage pipe. The Los Osos Valley Road Rehabilitation Project added two new drainage inlets, installed 310 feet of drainage pipe, and installed 450 feet of asphalt concrete roadway berm. The Orcutt Road Widening Project installed two new drainage inlets, 192 feet of new drainage pipe, as well as one small detention basin. Three additional drainage inlets were rehabilitated with the 2007-08 Microsurfacing project which will improve their ability to accept water. Over 1000 feet of Corrugated Metal Pipe (CMP) has been removed and replaced or rehabilitated along with several other CMP replacement projects soon to be advertised for bids. This will reduce the sediment load being carried in the pipes. The absence of the pipe bottom from rusting allows the dirt around the pipe 2- 3 2008-09 Winter Prep Page 4 to be drawn in and transported downstream. Two silt removal projects were completed in the summer of 2007 as part of the City's rotating silt removal program. The Stormwater Detention Role of Laguna Lake One very important feature of the City's storm water management that is perhaps unnoticed is the tremendous storm water detention capability of Laguna Lake. With its outlet at 122 feet above sea level, and a level of 127 feet as the flood level, Laguna Lake can provide storage fora huge amount of water before any nearby areas begin flooding. Because the lake increases from about 110 acres to over 200 acres between elevations 122 and 127, there is a storage capacity of approximately 800 acre-feet of water (i.e., 5 feet by 160 acres). Since an acre-foot of water equals approximately 326,000 gallons of water, 800 acre-feet of storage equals over 260 million gallons of storage capacity. Furthermore, this storage is not static: during storm events water is both entering and leaving the lake at a relatively high rate, so the storage amount represents what can be safely stored during a major storm event or events. It was clearly demonstrated during the intense storms of January and February 2008 that the storm water detention role of Laguna Lake is a tremendous"safety valve" for that part of town near the lake. Miscellaneous Preparations Sand has been delivered to the Corporation Yard, Laguna Lake Golf Course, Sinsheimer Park and Santa Rosa Park and is available to the public in the event they experience localized flooding. Staff has filled and palletized sandbags for emergency response and all chainsaws have been checked and repaired. Although we keep the Winter Weather web page available all year, staff places a reminder about the web site and the need to prepare on Channel 20. Radios are being delivered to response crews in the event we lose cell phone contact. FISCAL IMPACT The City has been receiving approximately $100,000 of funding through the Zone 9 Flood Control and Water Conservation District for natural channel clearing and public outreach. While this funding has a long tradition of being available to the City for this type of work, it is discretionary on the part of the County Board of Supervisors to provide it. With the exception of the silt removal projects, the remainder of the Capital Improvement projects are funded with General Fund. tdcouncil agenda mptmsspuhlic works carstonnwatcr L'.-2.0%Ooodprcp,doe O