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HE CITY OF .� m9 e.,. LEASAINTONo MEMORANDUM Date: October 3, 2008 To: Nelson Fialho, City Manager From: Jim Kelcourse, City Engineer Subject: Cost sharing of storm drain/erosion repairs to the Lund Ranch Tank Access Road The Lund Ranch Water Tank Access Road and storm drain system is in need of repairs. The drainage ditch on the south side of the access road collects runoff from the roadway and then directs water underground into a drainage pipe. In collecting flows, the inlet has plugged with leaves and debris and has allowed water to overflow and create voids adjacent to the inlet and along the 12-inch pipe under the roadway. In addition to the undermining of the access road piping and the inlet, significant erosion has occurred on the roadway down slope. As a result,the existing rip-rap structure on the down slope has failed. The developer, Greenbriar Homes,put in these storm drain improvements years ago and the improvements were accepted by the City. There have been several discussions about these repairs and Greenbriar has hired the firm of ENGEO to come up with some proposed design solutions. We have reviewed the proposed changes and have some minor modifications to their plans, but believe that if our changes are incorporated,the proposed changes can provide a solution to the problem. In our meetings with Greenbriar, we both recognized the need to complete the improvements before the winter rains begin, since we could encounter additional damage due to storm flows. In discussing responsibility for the improvements, they cite the lack of ongoing maintenance of the channel, additional flows into drainage system when flushing the City's water tank, and the fact the improvements were accepted by the City back in January of 2002. We believe the original design required too much ongoing maintenance to be successful and it's hard to assess whether the tank's discharge had any or no effect on the system. Greenbriar, in an effort to reach a compromise,has suggested that they hire a contractor to perform the work per ENGEO's recommended design changes and split the construction costs with the City. In an effort to resolve this issue in a timely manner and avoid additional damage and costs, it is recommended that we move forward with the repairs. Greenbriar has estimated the construction costs at$94,000. As part of the CIP program, we specifically included$75,000 for erosion and storm repairs for this type of repairs. Therefore, it is recommended that we have Greenbriar perform the work and reimburse them for our share of the cost, estimated at$56,400, which includes a 20%contingency.