RIO VISTA MUNICIPAL AIRPORT

Transcription

1 DRAINAGE TECHNICAL MEMORANDUM RIO VISTA MUNICIPAL AIRPORT RIO VISTA, CALIFORNIA Prepared for: City of Rio Vista 1 Main Street Rio Vista, CA (707) Prepared by: August 2012 Copyright 2012 Kimley-Horn and Associates, Inc.

2 DRAINAGE TECHNICAL MEMORANDUM FOR RIO VISTA MUNICIPAL AIRPORT Prepared for: City of Rio Vista 1 Main Street Rio Vista, CA (707) Prepared by: Kimley-Horn and Associates, Inc. 401 B Street Suite 600 San Diego, Ca This document, together with the concepts and designs presented herein, as an instrument of service, is intended only for the specific purpose and client for which it was prepared. Reuse of and improper reliance on this document without written authorization and adaptation by Kimley- Horn and Associates, Inc. shall be without liability to Kimley-Horn and Associates, Inc Rio Vista Municipal Airport Drainage Technical Memorandum /

3 Section 1 GLOSSARY... 1 Section 2 EXECUTIVE SUMMARY... 2 Section 3 INTRODUCTION... 3 Section 4 DATA COLLECTION... 4 Section 5 PROPOSED DRAINAGE IMPROVEMENTS... 9 Appendices Appendix A Appendix B Appendix C 2006 Preliminary Catch Basin and AC Repair Drainage Network Schematic Drawing Proposed Realignment of Watson Hollow Drainage Channel Rio Vista Municipal Airport Drainage Technical Memorandum / i

4 SECTION 1 GLOSSARY ACIP Airport Capital Improvement Program AIP Airport Improvement Program FAA Federal Aviation Administration Rio Vista Municipal Airport Drainage Technical Memorandum/

5 SECTION 2 EXECUTIVE SUMMARY The purpose of this report is to provide an assessment of current drainage infrastructure issues at the Rio Vista Municipal Airport and provide proposed improvements with associated opinions of probable cost for inclusion in the Airport Capital Improvement Program (ACIP) to obtain funding from the Airport Improvement Program (AIP). This report addresses the existing drainage infrastructure discussed during a meeting held on January 18 th, Based upon the findings of this drainage improvement report, Kimley-Horn and Associates, Inc. recommends the following: Replace steep grate inlets as marked and replace adjacent pavement to provide a smooth transition and reduce ponding. Modify channel and sump area in the approach and adjacent to Runway 15. The modifications are necessary to enhance the Runway Safety Area, mitigate and prevent eroding existing airfield operational pavements and to mitigate wildlife hazards. Rio Vista Municipal Airport Drainage Technical Memorandum/

6 SECTION 3 INTRODUCTION Kimley-Horn and Associates, Inc. (KHA) has been retained by the City of Rio Vista to provide an assessment of the existing problematic drainage infrastructure at the Rio Vista Municipal Airport and provide proposed projects with associated opinions of probable cost for development of funding dollars for the Airport Capital Improvement Program (ACIP) with the aim of encumbering funding through the Airport Improvement Program (AIP). The Rio Vista Municipal Airport is located three (3) miles northwest of the center of Rio Vista. The airport is located twenty (20) feet above sea level. The airport contains two (2) runways (Runway 7-25 and Runway 15-33), three (3) parallel taxiways (Taxiway A, Taxiway B, and Taxiway C), and a helipad. Runway is twenty-two hundred (2,200) feet in length and sixty five (65) feet wide. Runway 7-25 is forty-two hundred (4,200) feet in length and seventy five (75) feet wide. The helipad has dimensions of one hundred eighty (180) feet by one hundred eighty (180) feet. As of 2010, there were thirty-seven (37) primarily single engine aircraft based on the field. Aircraft operations average ninety-six (96) per day. KHA reviewed existing problematic drainage infrastructure at the Rio Vista Municipal Airport. This assessment included verifying information from an aerial survey conducted in January of 2011 with respect to inlets and adjacent channel erosion. KHA documented the concerns of both the Airport and tenants including the Travis Aero Club. The Travis Aero Club made recommendations for grate inlets that were safety hazards to small aircrafts. Based on the field observations and the discussions with the Airport and the Travis Aero Club, KHA has proposed rebuilding the noted inlets. KHA revisited the site in March of 2012 to observe the condition of the Watson Hollow Drainage Channel and surrounding sump. The purpose of this visit was to look for signs of meandering or erosion near Runway 15, Taxiway B, and along the northern edge of Runway Based on KHA s observations, corrective recommendations are suggested in Section 5. Rio Vista Municipal Airport Drainage Technical Memorandum/

7 SECTION 4 DATA COLLECTION Kimley-Horn and Associates, Inc. (KHA) conducted field observations of the existing problematic drainage infrastructure. As part of the field observations, KHA verified data from the aerial survey, available as-built drawings, and the Rio Vista Municipal Airport Master Plan (June 2007). A meeting was held on January 18th, 2011 at the Rio Vista Municipal Airport to discuss the Airport Staff and the Travis Aero Club concerns with the existing drainage features at the airport. The drainage issues from the meeting include steep depressions at grate inlets near the aircraft parking and hangars. The steep drainage inlets are marked with an X and can cause aircraft to bottom out and strike their propellers. Pilots currently navigate around these inlets. See Photo 1-5 for the steep grate inlets viewed in the field and Figure 1 for locations. Preliminary construction drawings have been completed for the steep grate inlets by Dillon and Murphy, see Appendix A. These drawings propose rehabbing the adjacent pavement of the grate inlets. Also, it was noted that runoff ponding in the vegetated sump northeast of Runway is often full of water during rain events. The Watson Hollow Drainage Channel runs west to east along the northern boundary of the Airport. The channel backs up into a sump area northeast of Runway At the channel s closest point, it is approximately 15 from the edge of pavement along the northwest edge of Taxiway B run-up area. A subsequent field visit was made to verify the inlets from the aerial survey and observe the condition of the Watson Hollow Drainage Channel and surrounding sump. The existing drainage system consists of a series of catch basins that outfall into the surrounding drainage channel at various points. In total there are 83 catch basins, 1 manhole, and 6 outfall locations that make up the drainage system within the airport fence line. 5 of the outfall locations are located in the drainage channel to the south/southeast of the airport. One outfall, which is responsible for all of the drainage structures north of Runway 7-25, outlets into the Watson Hollow Drainage Channel north of Runway The pavement areas near the sump were concerning, as erosion from storm water runoff was beginning to take effect and creep towards the pavement areas. Coincidentally, precipitation was in the forecast on this follow-up visit. KHA was able to observe the patterns of runoff towards the sump and channel. As the rain water flowed off the pavement, the steep slopes leading to the sump allowed the runoff to gain velocity and start the erosion process. To prevent any further damage, KHA recommends a realignment of the channel as further discussed in Section 5. Rio Vista Municipal Airport Drainage Technical Memorandum/

8 Photo 1: CB #1 Photo 2: CB #2 Rio Vista Municipal Airport Drainage Technical Memorandum/

9 Photo 3: CB #3 Photo 4: CB#4 Rio Vista Municipal Airport Drainage Technical Memorandum/

10 Photo 5: CB#5 Photo 6: Vegetated Sump Facing East Rio Vista Municipal Airport Drainage Technical Memorandum/

11 Photo 7: Vegetated Sump Facing West off of TW B Run-up Photo 8: Signs of Erosion along TW B Run-up 8 Rio Vista Municipal Airport Drainage Technical Memorandum/

12 SECTION 5 PROPOSED DRAINAGE IMPROVEMENTS Based on the existing conditions, KHA recommends raising the grate inlets and rehabbing the surrounding pavement. The opinion of probable construction cost is $10,000 for each inlet; see Table 1 for design fee and timeline. During final design, it may be determined that repaving and regrading the surrounding pavement is sufficient. The existing drainage features look to be in good working order. There is some erosion caused by standing water and/or wildlife around some of the turf catch basins on the south side of Runway These areas should be modified to mitigate safety concerns. The sump area adjacent to Watson Hollow Drainage Channel and west of Runway appear to be heavily vegetated and stable. KHA recommends monitoring this area for erosion and signs of meandering. However, the sump area to the east of Taxiway B is eroding the runway/airport operations area as shown in Photo 8. Due to the sheet flow of surface runoff in that area, the erosion problem along Taxiway B will only be exacerbated over time. KHA recommends that drainage improvements be made to prevent the erosion from compromising the existing pavement section via soil stabilization and drainage infrastructure improvements. Continuous monitoring and maintenance of the vegetated areas along Taxiway B and Runway is essential to help mitigate wildlife and prevent future erosion from adversely affecting the existing pavement and creating a hazard to aircraft and navigation. KHA proposes a more permanent, long term solution for the Watson Hollow Drainage Channel. Based on preliminary research and information, KHA recommends encasing the channel in a culvert from its entrance on to the airport property on the North west side near Airport Road, to the T intersection along the northern border with the adjacent property. A schematic of the culvert can be found in Appendix C. Encasing the channel in a culvert allows for the geometry of the culvert to be altered so the channel may be moved further away from airport operational areas. This would immediately improve operational safety in a few ways. First, it would reduce any potential conflicts with aircraft and wildlife by relocating any wildlife attractants further away from airport operational areas. Second, it also allows for improved grading and stabilization along the runway and taxiway safety areas, especially along the Taxiway B run-up pad. The design fee and construction cost for the culvert recommendation are listed below in Table 1. It should be noted that a project of this magnitude will require an environmental study (NEPA/CEQA). These studies can take between months to complete. The estimate in Table 1 includes the cost and duration for a NEPA/CEQA study as well as 25% design fee. The cost breakdown assumes that no mitigation is required prior to the start of construction. Due to the myriad of variables associated with an environmental study, it is not feasible to speculate what potential mitigation factors, if any, may be required prior to construction of the covered culvert. Rio Vista Municipal Airport Drainage Technical Memorandum/

13 Table 1: Recommended Improvement Summary NEPA/CEQA (incl 25% Design)(RSA/Drainage/Wildlife) Total Cost Federal Share (90%) $400,000 $360,000 $360,000 FY2013 FY2014 FY2015 FY2016 Administration (City) $60,000 $54,000 $13,500 $13,500 $13,500 $13,500 Design (RSA/Drainage/Wildlife) $270,000 $243,000 $243,000 Construction (RSA/Drainage/Wildlife) $3,000,000 $2,700,000 $1,350,000 $1,350,000 Construction Administration $270,000 $243,000 $121,500 $121,500 Federal Share (Grant Amount) $373,500 $256,500 $1,485,000 $1,485,000 Total Project $415,000 $285,000 $1,650,000 $1,650,000 Local Share $41,500 $28,500 $165,000 $165,000 Rio Vista Municipal Airport Drainage Technical Memorandum/

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15 APPENDIX A Rio Vista Municipal Airport Drainage Technical Memorandum / Appendices

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19 APPENDIX B Rio Vista Municipal Airport Drainage Technical Memorandum / Appendices

20 LEGEND ON-AIRPORT STORM DRAIN NETWORK OBSERVATIONS CATCH BASINS IN STORM DRAIN NETWORK = 83 MANHOLES IN STORM DRAIN NETWORK = 1 OUTFALL LOCATIONS IN STORM DRAIN NETWORK = 6 CATCH BASIN MANHOLE STORM DRAIN PIPE AIRPORT FENCE LINE DRAINAGE SWALE AIRPORT PAVEMENT AIRPORT BUILDING

21 APPENDIX C Rio Vista Municipal Airport Drainage Technical Memorandum / Appendices

22 Existing Condition Areas of Concern as it relates to wildlife hazards and bird attractants during take off and landing. Areas being washed out and eroded which will eventually cut into safety and object free areas. Run-up apron already showing signs of failure. Proposed Project feet meters Replace open channel with enclosed culvert and basin away from operational areas