HomeMy WebLinkAboutChapter 7 - Refined Alternatives
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REFINED ALTERNATIVES
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Chapter Seven - Refined Alternatives
INTRODUCTION
This chapter revises and/or combines several ofthe individual alternatives presented in the previous chapter. The
refined alternatives are based on input from Airport Management, the City of Sebastian, Indian River County, the
Florida Department of Transportation (FDOT), and the Federal Aviation Administration (FAA), as well as
comments received during meetings with the Technical Review Committee and the general public. Refinements
to the alternatives analysis essentially follow the same general order of presentation utilized in the previous
chapter. However, revisions are predominantly limited to the selected airfield and general aviation facility
alternatives, with a discussion of the environmental factors considered. No changes were made to the
navigational aids or economic development alternatives.
AIRFIELD FACILITIES
The facility requirements analysis identified airfield improvements required for the Sebastian Municipal Airport
over the course of the planning period. The viability of several key improvements was subsequently analyzed in
the analysis of airfield alternatives. These consisted of three options for the required crosswind runway, as well
as an analysis of the taxiway alternatives available. The crosswind runway and taxiway enhancements are
addressed further in this chapter. All other airfield improvements have been considered necessary for the
continued maintenance and development of the airfield system at Sebastian Municipal, and did not possess
alternative approaches.
Crosswind Runway Alternative
Improvement to the crosswind runway is by far the most significant airfield development action facing Sebastian
Municipal over the course of the planning period. As such, even the selected alternative to close Runway 13-31
and re-open Runway 9-27 provided a variety of approaches to meet the needs of the airfield. Based on the
assessment contained in the airfield alternatives, considerable discussion was generated regarding the potential
options to re-open Runway 9-27, their attributes and constraints, and the potential construction and funding
considerations that affected their implementation. It was determined in the facility requirements and alternatives
analysis that a length of 3,200 feet was required for Runway 9-27 to accommodate A-I and B-1 aircraft. The
pavement of the original Runway 9-27 alignment measures 4,000 feet long by 150 feet wide. This provided a
number of opportunities for the overlay of the required 3,200-foot long by 75-foot wide runway for small aircraft
crosswind operations.
The proximity of facilities to the north and south of Runway 9-27 dictated that the lateral alignment would have to
follow the original runway centerline. This ensures that the proper offset and vertical clearances are achieved on
both sides of the new 75-foot wide runway. Re-opening the runway on either the northern or southern half of the
150-foot wide pavement would create violations to the required transitional slopes. Therefore, the reconstruction
of the new 75-foot wide Runway 9-27 will be centered on the existing 150-foot wide pavement surface.
With an existing 4,000-foot length, various options existed to displace the new 3,200-foot length east or west
along the pavement available. Because the new runway will be a prepared surface, an offset of 200 feet is
required off each threshold. It is at this point that the associated 20: 1 approach surfaces begin. As a utility
runway (serving aircraft of 12,500 pounds or less), criteria in Federal Aviation Regulation (FAR) Part 77,
"Objects Affecting Navigable Airspace" necessitate the 20: 1 surface for both visual and non-precision instrument
approaches. FAR Part 77 also requires that any public road that traverses beneath a runway's approach, maintain
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a minimum clearance of 15 feet between the road and required approach surfaces. To the immediate west of
Runway 9-27 is Airport Drive West, which runs north/south under the proposed approach to Runway 9. This
existing road is the controlling factor for the location of the Runway 9 approach. A distance of 300 feet at 20: 1
provides the 15-foot clearance. This is then added to the required 200-foot offset for the beginning of the
approach surface to arrive at the overall 500-foot displacement from the end of the original Runway 9-27
pavement surface. This required displacement places the threshold along the eastern half of the old Runway 18-
36 alignment, which is also 150 feet wide. Because it was determined that the eastern half of the old Runway 18-
36 alignment would be utilized for a 35-foot wide north-south taxiway, this provided the final displacement for
the Runway 9 threshold. As such, the Runway 9 threshold has been located so that it is perpendicular or flush
with the edge of the 35-foot wide north-south taxiway. This provides an overall distance of approximately 590
feet from the centerline of Airport Drive West and the proposed Runway 9 threshold.
On the far end of the proposed runway, approximately 400 feet will exist between the proposed Runway 27
threshold and the eastern edge of the original Runway 9-27 pavement. Since more than 300 feet is available
beyond the end of the original pavement edge, there is adequate space to provide public road access into the area
located just northeast of the future Runway 4-22 and Runway 9-27 intersection. This spacing was made possible
by the relocation of the 11th hole of the Sebastian Municipal Golf Course. The final configuration of Runway 9-
27 is reflected on the various sheets of the Airport Layout Plan (ALP) set contained in the following chapter.
Crosswind Runway Enhancements
It should be noted that since Runway 9-27 will become the new crosswind runway for the airport, all of the
runway enhancements identified in the facility requirements for Runway 13-31 apply to Runway 9-27. These
include, but are not limited to the following:
+ Install Medium Intensity Runway Lights (MIRLs).
+ Construct a full-length parallel taxiway to Runway 9-27 with Medium Intensity Taxiway Lights
(MITLs) .
+ Re-mark Runway 9-27 after reconstruction to include non-precision runway markings.
+ Install Runway End Identifier Lights (REILs) to both ends of Runway 9-27.
+ Install Precision Approach Path Indicators (PAPIs) to both ends of Runway 9-27.
It is not intended for all of the improvements listed above to be complete when Runway 9-27 is re-opened. The
phasing of these projects is included in the 20 year CIP for Sebastian Municipal and are reflected on the ALP.
Discussions during the Technical Review Committee and public meetings revealed a desire to provide additional
runway length for the crosswind runway. Given the required clearances for the approach surfaces, the only
options available would be to utilize displaced thresholds on each end or to extend the runway to the east. The
application of displaced thresholds could potentially provide an additional 500 feet of takeoff length for
operations on Runway 9 and 400 feet on Runway 27, given the existing 4,000 feet of pavement. However, the
application of declared distances at a non-controlled general aviation airport, along with some line of sight issues
on the Runway 9 end, limit the viability of this option at this time. In addition, the costs associated with the
proper taxiway access, to prevent back-taxi operations, further undermine the feasibility of this option.
Nonetheless, it is recommended that the 500 and 400 feet of existing pavement before the proposed Runway 9 and
Runway 27 thresholds, respectively, be preserved for potential use in the future. The other option to extend the
runway to the east is simply not justified at this time.
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Taxiway Enhancements
The taxiway options discussed in the alternatives analysis were somewhat limited due to the airfield
configuration. Based on the recommended airfield and facility development options, there are no refinements
necessary. The recommendation to ultimately provide a full-length parallel taxiway to both Runway 4-22 and
Runway 9-27 remains. Likewise, the recommendation of placing the Runway 4-22 parallel taxiway to the
northwest and the Runway 9-27 parallel taxiway to the north are necessary to support the existing facilities of the
airfield and those proposed. Due to existing conditions and operational considerations, the phasing of airfield
improvements will require the construction of the full-length parallel taxiway to Runway 9-27 to occur
simultaneously with or immediately after the runway re-opening. While the option to provide a parallel taxiway
to the south of Runway 9-27 has some merit, the north parallel better supports the proposed development of
general aviation facilities. While not shown on the ALP plans, a taxiway to the south of Runway 9-27 may prove
essential for the development of the airport beyond the needs identified in the 20 year planning period.
Run-up areas are proposed for each end of the two full-length parallel taxiways. The run-up area for Runway 4
has been situated to take full advantage of the existing pavement in this location. Similarly the run-up area on the
west end of the parallel taxiway to Runway 9-27 has been positioned on a portion of the old Runway 18-36
pavement. All of the run-up areas have been configured to allow use by multiple aircraft and to minimize the
affects of prop wash on tenant leaseholds. A fifth run-up area was included on the south side of Runway 9 along
the north-south taxiway. Because of the aviation related development between the approach ends of Runway 4
and Runway 9, this space provides pilots an area to conduct run-ups when departing on Runway 9, without having
to cross the runway. This area, which has also been situated on existing pavement from the old Runway 18-36
alignment, should be marked to minimize any prop wash for the tenants located south of the Runway 9 approach.
The five run-up areas are depicted on the ALP in the following chapter.
GENERAL AVIATION FACILITIES
Essentially, three alternatives were proposed for the development of additional Fixed Base Operator (FBO)
facilities. The recommendations for pursuing development of an FBO and general aviation facilities relied upon
the re-opening of Runway 9-27. Before this airfield alteration can occur, the facilities of three existing tenants
would have to be accommodated in different places. The following sections provide the proposed locations to
mitigate the displacement of these tenants. All of the following recommendations are based on the logical
sequence of events that must transpire in order for the closure of Runway 13-31 and re-opening of Runway 9-27
to occur with the minimal amount of interruption to airport operations. The following sections address the issues
related to those tenants that will be impacted by the proposed airfield development plan.
Relocation of Velocity
The four acres of Velocity's southern leasehold will be relocated to a site across the north-south taxiway, from
their northern leasehold. The configuration of this property is essentially the same as in the alternatives analysis,
but has been slightly adjusted to accommodate all of the setbacks required for the airfield. It is expected that the
site plan will have slight adjustments made before the relocation is conducted. Taking this into consideration, the
final site plan needs to consider all of the required airport design criteria, so as not to prevent the development of
airport facilities reflected in this study. The site reserved for Velocity is depicted on the ALP.
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Master Plan Update
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JS Aviation Leasehold
Although there have not been a lot of discussions held between the City and JS Aviation to date, a space has been
reserved on the west side of the airport for the relocation of JS Aviation's facilities. Primary considerations for
this location were based on terms contained in the existing leasehold between the City of Sebastian and JS
Aviation. With respect to the relocation of leased premises, the existing leasehold states:
"Following the Landlord's receipt of adequate funding for the re-activation plan for runway 9-27,
as depicted by the Master Plan for Sebastian Municipal Airport and contained in the Capital
Budget of the City of Sebastian, the Landlord shall construct a comparable building on an
alternative site at the Airport, comparable in size with the Existing Premises and with appropriate
access with comparable frontage on an existing taxiway of the Airport and to relocate the tenants
existing fuel farm or in the alternative install another of comparable size and capacity. ("New
Premises") Landlord shall give Tenant written notice of completion of the New Premises. Tenant
shall, within sixty (60) days from receipt of notice, relocate its business to the New Premises."
The site reserved on the west side of the airport is the only site that can truly meet the provisions required of the
leasehold. The problem with most other sites is that there are no existing taxiways available. Only the north-
south taxiway and the partial parallel taxiway to Runway 4-22 will be available when the re-activation of Runway
9-27 begins. The partial parallel to Runway 4-22 has no 1andside access, especially while Runway 13-31 is still
active. The partial parallel to Runway 13-31 does not provide adequate airfield access and is inaccessible while
Runway 13-31 is active. With respect to airfield location, the site reserved for JS Aviation on the west side ofthe
airfield is the only site that provides "comparable frontage on an existing taxiway of the Airport." This location
will place JS Aviation right between the approach to Runway 9 and Runway 4, very much like their current
location which is between the approaches to Runway 22 and Runway 31. Distinct advantages of the proposed site
include:
+
+
Better, safer, and more efficient access to the primary and crosswind runways.
Offers the opportunity for JS Aviation to operate in a location that has a lot of visibility and
access with respect to the operations of the airfield.
Provides a site that is compatible with the focus of activity and future development of the airport.
Removes the existing facility from the side of the airport with the highest density of non-
compatible residential development.
+
+
All of the facilities depicted are comparable with those currently in use by JS Aviation. The most significant
impact noted is the additional drive time it may take for some of the users to access the west, versus the eastside
of town. This impact, which was timed between five and seven minutes depending on origination and route of
travel, is considered minor. The area reserved for the relocated facilities of JS Aviation are depicted on the ALP.
Skydive Sebastian Landing Zone
As mentioned previously, there is no lease between the City and Skydive Sebastian for the exclusive use of a
landing zone. Therefore, as reflected in the previous Master Plan and Airport Layout Plan, the area that currently
serves as the Runway Protection Zone for Runway 13 has been reserved for the future landing zone. During the
course of this study, an alternative landing zone was considered in the South Infield area. However, after meeting
with the FAA, it was agreed that the site in the South Infield area was considered unsafe. The FAA stated that the
South Infield area suffers from the same safety problems that exist for the current landing zone in the North
Infield area. This problem is that either location requires the skydivers to cross an active taxiway and in some
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cases an active runway after landing. This practice is considered unacceptable by the FAA as it increases the risk
for an incursion to occur on the airfield.
In addition, during the course of the study, the ownership of Skydive Sebastian changed. Placing the future sky
diving landing zone to the northwest of Runway 13 keeps the airfield configuration the same as it was in the
previous Master Plan and Airport Layout Plan. Therefore, under this update, nothing directly related to Skydive
Sebastian will be changed, except for increasing the size of the landing zone as described below. This allows the
current owners of Sky dive Sebastian to continue operating under the same terms and conditions that were in place
when they purchased the business.
Previously the two proposed skydiving landing zones depicted in the alternatives analysis (Exhibit 6-4) were
shown as having a radius of 300 feet. While staff of Skydive Sebastian provided this dimension during the
inventory phase of the study, the current owners and users of the facility expressed a concern about the drop zone
size. As a result the 2001 Skydiver's Information Manual, which is published by the United States Parachute
Association, was consulted. The following excerpt is from Section 2 - Basic Safety Requirements (page 9) of this
document:
H
DROP ZONE REQUIRMENTS
1. Areas used for skydiving should be unobstructed, with the following minimum radial
distances to the nearest hazard:
a. solo students and A-license holders - 100 meters
b. B- and C-license holders - 50 meters
c. D- license holders - unlimited
2. Hazards are defined as telephone and power lines, towers, buildings, open bodies of
water, highways, automobiles, and clusters of trees covering more than 3,000 square
meters.
3. Manned ground-to-air communication (e.g., radios, panels, smoke, lights) are to be
present on the drop zone during skydiving operations.
Using these industry guidelines, the landing/drop zone reserved for Skydive Sebastian was increased from the
original radius of 300 feet to 328 feet (100 meters). This zone, reflected on the ALP set, is unobstructed and clear
of any hazards, especially those called out in the 2001 Skydiver's Information Manual.
Other General Aviation Facilities
Adjustments were made to the selected FBO alternative from what was presented in the original alternatives
analysis. Changes were made to ensure Design Group II aircraft could utilize the facilities proposed. Key
improvements were made to allow this size of aircraft to access the fuel farm and parking area in front of the
clearspan hangar and general aviation terminal building. Similarly, the layout of various sized private hangar
facilities incorporate the required setbacks to accommodate Design Group II aircraft. The only exception was the
design criteria (Design Group I) used for the layout of the T -hangar facilities.
ENVIRONMENTAL CONSIDERATIONS
The purpose of this section is to provide a review of the environmental factors that were taken into consideration
during the analysis of airfield development alternatives. This section also addresses the existing and future noise
contours that were developed as part of the study.
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Environmental Assessment for Re-Opening Runway 9-27
As stated in the alternatives analysis, a detailed Environmental Assessment (EA) for the re-opening of Runway 9-
27 was conducted as part of the previous master plan. The FAA approved this EA in a letter dated March 9, 1994.
This letter details the FAA's "Finding of No Significant Impact" after evaluating the various categories required
for analysis. Since a significant amount of time has passed since the assessment was conducted, the EA will need
to be re-eva1uated. This re-eva1uation will necessitate the documentation, in letter form, of any changes that have
occurred since the original EA submittal. The only significant changes since 1994 relate to the proposed runway
length and level of operations.
The original 1994 plan to re-activate Runway 9-27 and close Runway 13-31 required a length of 4,000 feet for
Runway 9-27. All elements of this study reflect only a length of 3,200 feet for Runway 9-27. It is assumed that
the reduced length would not create any additional impact to the environment. If any, it is anticipated that the
reduction to the length of Runway 9-27 would lessen the impact to the surrounding community. As for the
changes in activity levels, the EA was based on the forecasts contained in the 1993 Master Plan. The update to
these figures (Chapter 3) documented how the projections contained in the 1993 Master Plan were never realized.
Therefore, any community impacts that were attributed to aircraft overflights and/or noise will be less. The noise
contours generated as part of this study, and which would be used to update the EA, are described in the following
section.
Generation of Noise Contours
Noise contours for the 65, 70, and 75 Day Night Sound Level (DNL) were generated using the latest version of
the FAA Integrated Noise Model (INM) software. DNL was developed as a single number measure of
community noise exposure. Introduced as a simple method for predicting the effects on a population of the
average long-term exposure to noise, DNL is an enhancement of the Equivalent Sound Level (Leq) metric
through the addition of a 10 dB penalty for nighttime (10 p.m. to 7 a.m.) noise intrusions. The incorporation of
the 10 dB penalty is in recognition of the increased annoyance that is generally associated with noise during the
later night hours. DNL employs the same energy equivalent concept as Leq and uses a 24-hour time integration
period. For assessing long-term noise exposure, the yearly average DNL is the specified metric by the FAA in
their FAR Part 150 Noise Compatibility Planning process. The DNL metric was also accepted by the United
States Department of Housing and Urban Development, the Environmental Protection Agency, and the Council
on Environmental Quality for use in assessing aviation related cumulative noise impacts. The DNL noise metric
has emerged as a highly workable tool for land use planning and in relating noise, particularly aircraft noise, to
community reaction. DNL has also been employed to establish specific criteria relative to the compatibility
between various forms ofland use and increasing levels ofDNL noise exposure.
The contours for Sebastian Municipal were based on the activity levels and aircraft types for the base year (2000)
and 2012. Existing noise contours were generated using the Runway 4-22 and Runway 13-31 configuration,
while the 2012 model utilized the Runway 4-22 and Runway 9-27 layout. As depicted on the Airport Land Use
Plan, only the 65 and 70 DNL contours for 2012 are depicted, neither of which extend beyond the current airport
property line. While it was modeled, the 75 DNL did not appear in the INM results. Close scrutiny of the
contours will show that more operations were modeled on Runway 9-27 versus Runway 4-22. This is based on
the information provided by the tenants and users interviewed as to which runway they would use most should
Runway 9-27 re-open. The shorter taxi times for most tenants to the east-west runway supports this utilization.
This plan also depicts the aircraft traffic patterns for both runways. Standard traffic patterns at an airport have
aircraft making all turns to the left. The left-hand turn facilitates the pilot's ability to keep the runway
environment in sight since he sits on the left-hand side of the aircraft. However, right-hand traffic patterns are
also utilized for various reasons, not the least of which is for noise abatement and the prevention of aircraft
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overflights. Currently, all four runway ends at Sebastian Municipal have standard left-hand traffic patterns. It is
the intention of Airport Management and the City of Sebastian to publish right-hand traffic patterns for Runway
22 and Runway 27. This means that all of the traffic and turns associated with Runway 4-22 will be on the
northeast side of the runway and all of the traffic and turns associated with Runway 9-27 will all be on the north
side of the runway. The intent is to reduce as much as possible the number of aircraft flights over residential
areas.
It should be noted that proper procedures at an uncontrolled field like Sebastian Municipal require that aircraft
enter the traffic pattern in level flight, abeam the midpoint of the runway, and at pattern altitude. These
procedures are documented in the FAA's Aeronautical Information Manual (AIM) -Basic Flight Information and
Air Traffic Control Procedures. While these changes in traffic patterns will not eliminate those aircraft that
deviate from the proper traffic patterns or those that use straight-out departures, it should help reduce the number
of flights over the communities surrounding the airfield. However, it is difficult to control those aircraft that
operate beyond the boundaries of the standard sized traffic pattern.
Scrub Jay Buffer
The Florida scrub jay has been well documented in the vicinity of the airfield by the Florida Game and Fresh
Water Fish Commission. In 1999, a Florida scrub jay management plan was written, which incorporated portions
of the Sebastian Municipal Airport. To facilitate recommendations in this plan, the City of Sebastian, the FAA,
and FDOT agreed to provide a 100-foot wide flight corridor for the Florida scrub jay. This buffer zone is
depicted on the ALP set. During the layout of the proposed facilities, no impacts were made to this lOO-foot wide
path that primarily follows the property line on the north side of the airport.
Wetlands and Water Quality
At the onset of the master plan, a field investigation was conducted to determine the extent of wetlands on the
airport property. This study did not include any wetland flagging, nor was it coordinated with the Army Corps of
Engineers or St. John's River Water Management District. However, it did provide useful information that was
utilized in the location of future facilities. As for water quality, a complete master drainage study is also being
conducted simultaneous with this master plan. The master drainage study incorporates all of the existing and
proposed facilities depicted on the ALP set in the following chapter.
Future Land Use
Sebastian Municipal Airport has committed much of its available land area for development of either airfield or
general aviation facilities. Additional land to the east and west of these facilities is available for commercial and
industrial development. Remaining areas of land not presently committed to development in most instances are
situated in areas either difficult to develop, such as off the ends of runways, or surrounded by active airfield
pavements. Throughout the study, the goal has been to satisfy the needs of the airport and facilitate revenue
generation, all while ensuring the safety and compatibility of the areas surrounding the airport. The airport
developments proposed in this study and on the ALP set do not require any of the current City of Sebastian or
Indian River County land use designations to change. Likewise, no property acquisitions for the airport are
required for the planned development.
SUMMARY
The preceding sections have reviewed a series of issues and questions that arose from discussions of the
alternatives as well as the review of the previous chapters. With these refinements in mind, the next step of the
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process is to develop the ALP set to depict the existing and future airport facilities. The drawings that make up
this set are discussed in the following chapter.
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