rio vista municipal airport · travis aero club concerns with the existing drainage features at the...

August 2012

Copyright © 2012 Kimley-Horn and Associates, Inc.

DRAINAGE TECHNICAL MEMORANDUM

RIO VISTA MUNICIPAL AIRPORT

RIO VISTA, CALIFORNIA

Prepared for:City of Rio Vista1 Main StreetRio Vista, CA 94571(707) 374-5337

Prepared by:

Rio Vista Municipal Airport – Drainage Technical Memorandum / 094632000

DRAINAGE TECHNICAL MEMORANDUM

FOR

RIO VISTA MUNICIPAL AIRPORT

Prepared for:City of Rio Vista1 Main StreetRio Vista, CA 94571(707) 374-5337

Prepared by:

__________________________________

Kimley-Horn and Associates, Inc.401 B Street Suite 600San Diego, Ca 92101619-234-9411

This document, together with the concepts and designs presented herein, as an instrument ofservice, is intended only for the specific purpose and client for which it was prepared. Reuse ofand 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.

2012

iRio Vista Municipal Airport – Drainage Technical Memorandum / 094632000

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 2006 Preliminary Catch Basin and AC Repair

Appendix B Drainage Network Schematic Drawing

Appendix C Proposed Realignment of Watson Hollow Drainage Channel

1Rio Vista Municipal Airport – Drainage Technical Memorandum/ 094632000

SECTION 1 GLOSSARY

ACIP– Airport Capital Improvement Program

AIP – Airport Improvement Program

FAA – Federal Aviation Administration


SECTION 2 EXECUTIVE SUMMARY

The purpose of this report is to provide an assessment of current drainage infrastructure issues at the Rio VistaMunicipal Airport and provide proposed improvements with associated opinions of probable cost for inclusion inthe 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,2011.

Based upon the findings of this drainage improvement report, Kimley-Horn and Associates, Inc. recommends thefollowing:

Replace steep grate inlets as marked and replace adjacent pavement to provide a smooth transition andreduce ponding.

Modify channel and sump area in the approach and adjacent to Runway 15. The modifications arenecessary to enhance the Runway Safety Area, mitigate and prevent eroding existing airfield operationalpavements and to mitigate wildlife hazards.


SECTION 3 INTRODUCTION

Kimley-Horn and Associates, Inc. (KHA) has been retained by the City of Rio Vista to provide an assessment ofthe existing problematic drainage infrastructure at the Rio Vista Municipal Airport and provide proposed projectswith associated opinions of probable cost for development of funding dollars for the Airport Capital ImprovementProgram (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 islocated 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 15-33 istwenty-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 aircraftbased on the field. Aircraft operations average ninety-six (96) per day.

KHA reviewed existing problematic drainage infrastructure at the Rio Vista Municipal Airport. This assessmentincluded verifying information from an aerial survey conducted in January of 2011 with respect to inlets andadjacent channel erosion. KHA documented the concerns of both the Airport and tenants including the TravisAero Club. The Travis Aero Club made recommendations for grate inlets that were safety hazards to smallaircrafts. Based on the field observations and the discussions with the Airport and the Travis Aero Club, KHAhas proposed rebuilding the noted inlets.

KHA revisited the site in March of 2012 to observe the condition of the Watson Hollow Drainage Channel andsurrounding 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 7-25. Based on KHA’s observations, correctiverecommendations are suggested in Section 5.


SECTION 4 DATA COLLECTION

Kimley-Horn and Associates, Inc. (KHA) conducted field observations of the existing problematic drainageinfrastructure. As part of the field observations, KHA verified data from the aerial survey, available as-builtdrawings, 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 theTravis Aero Club concerns with the existing drainage features at the airport. The drainage issues from themeeting include steep depressions at grate inlets near the aircraft parking and hangars. The steep drainage inletsare marked with an “X” and can cause aircraft to bottom out and strike their propellers. Pilots currently navigatearound 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, seeAppendix 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 15-33 is often full of waterduring rain events. The Watson Hollow Drainage Channel runs west to east along the northern boundary of theAirport. The channel backs up into a sump area northeast of Runway 15-33. At the channel’s closest point, it isapproximately 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 theWatson Hollow Drainage Channel and surrounding sump. The existing drainage system consists of a series ofcatch 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 outfalllocations are located in the drainage channel to the south/southeast of the airport. One outfall, which isresponsible for all of the drainage structures north of Runway 7-25, outlets into the Watson Hollow DrainageChannel north of Runway 15-33.

The pavement areas near the sump were concerning, as erosion from storm water runoff was beginning to takeeffect and creep towards the pavement areas. Coincidentally, precipitation was in the forecast on this follow-upvisit. KHA was able to observe the patterns of runoff towards the sump and channel. As the rain water flowed offthe pavement, the steep slopes leading to the sump allowed the runoff to gain velocity and start the erosionprocess. To prevent any further damage, KHA recommends a realignment of the channel as further discussed inSection 5.


Photo 1: CB #1

Photo 2: CB #2


Photo 3: CB #3

Photo 4: CB#4


Photo 5: CB#5

Photo 6: Vegetated Sump Facing East


Photo 7: Vegetated Sump Facing West off of TW B Run-up

Photo 8: Signs of Erosion along TW B Run-up


SECTION 5 PROPOSED DRAINAGE IMPROVEMENTS

Based on the existing conditions, KHA recommends raising the grate inlets and rehabbing the surroundingpavement. The opinion of probable construction cost is $10,000 for each inlet; see Table 1 for design fee andtimeline. During final design, it may be determined that repaving and regrading the surrounding pavement issufficient.

The existing drainage features look to be in good working order. There is some erosion caused by standing waterand/or wildlife around some of the turf catch basins on the south side of Runway 7-25. These areas should bemodified to mitigate safety concerns.

The sump area adjacent to Watson Hollow Drainage Channel and west of Runway 15-33 appear to be heavilyvegetated 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 Photo8. Due to the sheet flow of surface runoff in that area, the erosion problem along Taxiway B will only beexacerbated over time. KHA recommends that drainage improvements be made to prevent the erosion fromcompromising the existing pavement section via soil stabilization and drainage infrastructure improvements.

Continuous monitoring and maintenance of the vegetated areas along Taxiway B and Runway 15-33 is essentialto help mitigate wildlife and prevent future erosion from adversely affecting the existing pavement and creating ahazard to aircraft and navigation. KHA proposes a more permanent, long term solution for the Watson HollowDrainage Channel. Based on preliminary research and information, KHA recommends encasing the channel in aculvert 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 inAppendix C.

Encasing the channel in a culvert allows for the geometry of the culvert to be altered so the channel may bemoved further away from airport operational areas. This would immediately improve operational safety in a fewways. First, it would reduce any potential conflicts with aircraft and wildlife by relocating any wildlife attractantsfurther away from airport operational areas. Second, it also allows for improved grading and stabilization alongthe 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 benoted that a project of this magnitude will require an environmental study (NEPA/CEQA). These studies can takebetween 18 – 24 months to complete. The estimate in Table 1 includes the cost and duration for a NEPA/CEQAstudy as well as 25% design fee. The cost breakdown assumes that no mitigation is required prior to the start ofconstruction. Due to the myriad of variables associated with an environmental study, it is not feasible to speculatewhat potential mitigation factors, if any, may be required prior to construction of the covered culvert.


Table 1: Recommended Improvement Summary

Total CostFederalShare(90%)

FY2013 FY2014 FY2015 FY2016

NEPA/CEQA (incl 25%Design)(RSA/Drainage/Wildlife) $400,000 $360,000 $360,000

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

Appendices Rio Vista Municipal Airport – Drainage Technical Memorandum / 094632000

APPENDIX A


APPENDIX B

CATCH BASIN

MANHOLE

STORM DRAIN PIPE

AIRPORT FENCE LINE

DRAINAGE SWALE

AIRPORT PAVEMENT

AIRPORT BUILDING

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


APPENDIX C

feetmeters

2000600

Areas being washed outand eroded which willeventually cut into safetyand object free areas.Run-up apron alreadyshowing signs of failure.

Areas of Concern as itrelates to wildlife hazardsand bird attractantsduring take off andlanding.

Replace open channelwith enclosed culvert andbasin away fromoperational areas.

Proposed Project

Existing Condition

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