04-14-14 Regular Meeting of La Porte City Council

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REQUEST FOR CITY COUNCIL AGENDA ITEMREQUEST FOR CITY COUNCIL AGENDA ITEM April 14, 2014April 14, 2014AppropriationAppropriation Agenda Date Requested:Agenda Date Requested: N/A N/A T. Tietjens T. Tietjens Source of Funds:Source of Funds: Requested By: Account Number:Account Number: Planning & Development Planning & Development Department: Amount Budgeted:Amount Budgeted: Report:Resolution:Resolution:Ordinance:Ordinance: Amount Requested:Amount Requested: Other: Budgeted Item:Budgeted Item:YESYESNONO Attachments :Attachments : 1. Pipeline Corridor Location1. Pipeline Corridor Location 2. Pipeline Project Layout2. Pipeline Project Layout 3. Preliminary Cost Estimate for Pipeline 3. Preliminary Cost Estimate for Pipeline CrossingCrossing SUMMARY & RECOMMENDATIONSSUMMARY & RECOMMENDATIONS The Planning Department is summarizing a series of studies and reports detailing the conditions and options for the The Planning Department is summarizing a series of studies and reports detailing the conditions and options for the ultimate improvements for the Lower San Jacinto Bay Watershed or F101ultimate improvements for the Lower San Jacinto Bay Watershed or F101--0000--00. The current problem of this 00. The current problem of this watershed, being one of 6 boundaries that serve the City of La Porte, is the ExxonMobil pipeline corridor, which watershed, being one of 6 boundaries that serve the City of La Porte, is the ExxonMobil pipeline corridor, which bisects the watershed and the allowance for the ultimate flow west of the pipeline corridor to drain east and bisects the watershed and the allowance for the ultimate flow west of the pipeline corridor to drain east and ultimately into the San Jacinto Bay. The pipeline corridor is 326 feet wide, runs in a north south direction acting as ultimately into the San Jacinto Bay. The pipeline corridor is 326 feet wide, runs in a north south direction acting as a barrier to the F101 flow of most of northwest La Porte. a barrier to the F101 flow of most of northwest La Porte. Several options were proposed and analyzed in an initial Master Drainage Plan study by Landev Engineers in Several options were proposed and analyzed in an initial Master Drainage Plan study by Landev Engineers in 1987. In that report, channel improvements were recommended for F 1011987. In that report, channel improvements were recommended for F 1011987. In that report, channel improvements were recommended for F 1011987. In that report, channel improvements were recommended for F 101----06060606----00 across the existing Exxon Mobil 00 across the existing Exxon Mobil 00 across the existing Exxon Mobil 00 across the existing Exxon Mobil pipeline corridor. Since the study in 1987, numerous additional pipelines have been laid within the corridor pipeline corridor. Since the study in 1987, numerous additional pipelines have been laid within the corridor rendering the original 1987 plan outdated. After completion of the 2009 Master Drainage Plan, the Drainage rendering the original 1987 plan outdated. After completion of the 2009 Master Drainage Plan, the Drainage Committee authorized the department to initiate a request to Harris County Flood Control District (HCFCD) to Committee authorized the department to initiate a request to Harris County Flood Control District (HCFCD) to fund a study of the pipeline restrictions. The study was authorized to evaluate alternatives and develop a plan for fund a study of the pipeline restrictions. The study was authorized to evaluate alternatives and develop a plan for conveyance improvements to HCFCD Unit F101conveyance improvements to HCFCD Unit F101--0606--00 across the ExxonMobil pipeline corridor into HCFCD 00 across the ExxonMobil pipeline corridor into HCFCD F101 and was completed in July 2013. F101 and was completed in July 2013. This recent study detailed depths and pipeline locations were obtained by hydroexcavation within the pipeline This recent study detailed depths and pipeline locations were obtained by hydroexcavation within the pipeline corridor. It was determined 44 pipelines are present. Various options were studied including 1) a siphon design corridor. It was determined 44 pipelines are present. Various options were studied including 1) a siphon design under the 44 pipelines, 2) acquiring Right of Way to widen the existing channel while maintaining the current flow under the 44 pipelines, 2) acquiring Right of Way to widen the existing channel while maintaining the current flow line of the channel, 3) an inline of the channel, 3) an in--line detention basin with flows across the corridor or 4) a high flow concrete lined line detention basin with flows across the corridor or 4) a high flow concrete lined channel with conduits under and between the existing pipelines to convey and provide ultimate flow across the channel with conduits under and between the existing pipelines to convey and provide ultimate flow across the corridor. The most economically feasible option was determined to be option four requiring minimal additional right corridor. The most economically feasible option was determined to be option four requiring minimal additional right of way and conduits, which would be able to cross the corridor. With this option only 2 pipelines would need to be of way and conduits, which would be able to cross the corridor. With this option only 2 pipelines would need to be relocated. The assumptions to make the recommendation of option 4 viable were 1) a variance in separation for a two foot The assumptions to make the recommendation of option 4 viable were 1) a variance in separation for a two foot