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HomeMy WebLinkAboutJ_Justification_180214_v11 7. CONDITIONAL USE PERMIT JUSTIFICATION Consistency With Plans and Regulations City of Renton Helipads may be permitted as a hearing examiner conditional use in the UC zone per Renton Municipal Zoning Use Table 4-2-060 as clarified by CI-126 condition number 78 which states that helipads are permitted south of Gene Coulon Park, north of North Park Drive or west of Logan Avenue and east of the Cedar River. State of Washington/King County Neither the state of Washington nor King County have regulations or design guidance related to public-use or private-use helicopter landing areas. Federal Federal Aviation Administration (FAA) The FAA’s authority with respect to helipads is in Federal Aviation Regulation Part 157 of Title 14 of the U.S. code. Part 157 requires sponsors of helicopter landing areas, except those intended for temporary use, to file FAA Form 7480-1 “Notice of Landing Area Proposal” prior to development. This initiates an FAA airspace review. The FAA uses Federal Aviation Regulation Part 77 “Airspace Obstruction Standards” as a guide when they conduct reviews. The FAA requires at least one approach/departure path along an 8:1 outward and upward slope that is either free of objects or, if minimal penetrations exist, that the objects are not considered hazards to flight. FAA reviews result in one of three determinations: (1) no objection, (2) no objection with mitigation or (3) objection – to the use of airspace. Results of airspace determinations are provided in letter form. Both the IBC and the IFC require “approval” of the FAA for helipads including those limited to private use. This is inaccurate. The FAA does not have the authority to approve or disapprove private-use heliports. All that is expected from the FAA is a letter indicating that they do not object to this use. Sufficient clear airspace exists east, south and west of Tower 2 to satisfy the FAA with respect to airspace. FAA Form 7480-1 was submitted by Seco Development on February 8, 2016. A response from the FAA indicated that the agency had no objection to the use of airspace for this site. All FAA 2 airspace determinations have expiration dates. The February 8 submission expired in August of this year. Another filing was made on November 10, 2017. This second submission is expected to result in the same determination as the original. The original response from the FAA and the new submission, FAA number 2017-WSA-37-LAP, are included in the appendix to this document. National Building Codes General Design for this helipad is consistent with the IBC, IFC and NFPA. To meet national codes primary items necessary are:  One code stair  A second method to access the occupied floor below which could be a hatch and vertical ladder  A 2-1/2” standpipe within 150’ of the landing area  Two 20A-160B fire extinguishers  A no-smoking sign or additional such signs as seems logical based on the overall design  A fire-pull station National Building Code Structural New structures such as Tower 2 are usually able to accommodate helicopters up to 10,000 pounds of operating weight. Airsafe recommends structural certification of helipads to the highest weight they can accommodate even if that weight is well above the weight of helicopters expected to use a facility. This is done to facilitate landings by larger helicopters in case of a local or regional emergency. The design helicopter for the Southport Office Helipad weights approximately 6,000 pounds. The structural engineer for the Southport Office Complex has provided a letter indicating that the helipad is consistent with requirements of IBC Section 1607.6 (2015). This letter is included in the appendix. Following are the verbatim structural requirements of the IBC for elevated helipads. Heliport and helistop landing areas shall be designed for the following loads, combined in accordance with Section 1607.6. 1. Dead load, D, plus the gross weight of the helicopter, Dh, plus snow load, S. 2. Dead load, D, plus two single concentrated impact loads, L, approximately 8 feet apart applied anywhere on the landing area, having a magnitude of 0.75 times the gross weight of the helicopter. Both loads acting together total one-and-one half times the gross weight of the helicopter. 3. Dead load, D, plus a uniform live load, L, of 100 psf 3 Appropriate Location This use is consistent with the UC zone. The proposed location of this helipad on Tower 2 of the Southport Office Complex is ideal when one considers this complex is to be a major business center and that helicopters are often used for efficient corporate transportation. Seco Development considers this proposed helipad to be a logical, beneficial, accessory use to a future center of concentrated business activity. The rooftop location provides a secure landing area that meets relevant national standards and FAA recommendations. Effect on Adjacent Properties This proposed helipad is expected to have minimal effect on adjacent properties. Its rooftop location and elevation relative to surrounding structures will minimize impacts. Noise is often cited as a negative effect when considering siting of helipads. A discussion of noise and the anticipated effect on adjacent properties resulting from this proposed use is included in the “Noise, Light and Glare” section below. Compatibility The area at which a helipad would be located on Tower 2 and airspace that would serve approaches and departures is large enough for safe flight operations. There is nothing about this proposed helipad, the airspace serving it or adjacent uses that would be incompatible with helicopter or helipad operations or flight safety. As to compatibility with tenants of Tower 2 and tenants of Towers 1 and 3, there are many examples where helipads and office complexes are successfully co-located. Examples of helipad compatibility as related to office complexes and populated areas are the Bank of America helipad in downtown Bellevue and all three television station helipads in downtown Seattle. Parking There are 2,121 parking stalls associated with the Southport project. These serve all three office structures and the Hyatt Regency Hotel. Additional parking will not be necessary to serve helipad operations. Traffic No additional vehicle trips are expected to be generated as a result of this proposed use. Noise, Light and Glare Noise Noise generated by light-turbine helicopters in the area around Tower 2 is not expected to be bothersome to nearby uses for a number of reasons. 4 The area has relatively high ambient noise levels created by a variety of uses including the Boeing paint operation, Renton Municipal Airport, seaplane activity, the I-405 freeway, and those activities/events generally found in metropolitan areas such as street traffic and emergency- vehicle sirens. Nearby Residential Uses The location of the helipad on Tower 2 and the relative arrangement of towers 2 and 3 with respect to nearby uses will serve to limit noise impacts. The nearest residential structures are Bristol I and Bristol II located approximately 700 feet north and 400 feet east respectively from the proposed helipad. Line-of-sight from the Bristol properties is blocked by Tower 2 and Tower 3. Notably, Tower 3 extends a considerable distance south of the Tower 2. This further blocks visibility of the helipad and will reduce noise impacts to the Bristol II complex. Another element, relative elevation, contributes to helipad compatibility with surrounding uses. Both Bristol I and Bristol II are about 40 feet lower than the Tower 2 rooftop. This elevation difference will allow the Tower 2 roof and parapets to reduce noise impacts. Hyatt Impacts Helipad operations are not expected to be bothersome to clients of the Hyatt Regency Hotel due to the hotel’s location north of the landing area, the blocking effect of Tower 2 and that helicopter flight operations would be conducted south of Tower 2 which is south of the hotel. Further, it is likely that the helipad will be complimentary to hotel operations. Many high-end hotels have rooftop helipads to serve clients. General Noise Factors Noise generated by modern light-turbine helicopters continues to be reduced by technological improvements to engines and rotor systems. Modern light-turbine helicopters have considerably reduced noise levels compared to older helicopters. Modern light turbine helicopters have thirty-second post-landing cool-down periods. These periods are required by engine manufacturers to allow dissimilar metals to cool thereby reducing component wear. Similar running periods are required prior to take-off. This is an improvement over engines of just a decade ago that required two-minute cool down times. Primary concepts of the Helicopter Association International’s Fly Neighborly Program will be employed at this helipad. Fly Neighborly procedures include steeper descents and ascents and elimination of sharp turns that tend to increase helicopter noise. 5 Light Emissions From The Helipad Light emissions from the helipad will be unnoticeable by the general public due to the rooftop helipad location and use of low-wattage light emitting diodes (LEDs). The structural support area of the helipad will be defined by eight perimeter lights that are flush with the concrete landing surface. Each of the perimeter lights will have eight (8) watts of power. A lighted wind indicator, also using LED technology will be visible to the public depending on their location and viewing angle. The perimeter lights and the lighted wind indicator will be activated within a few minutes of landing and will be turned off shortly after helicopter departure. Flood lights will not be used to illuminate the helipad. It is important to note that factors that create good helipad design are beneficial to surrounding uses. A goal with helipad lighting is to use only the number of lights and cumulative light intensity sufficient to safely identify a helipad’s structural support area. Light intensity beyond that is not only useless but undesired as it serves to reduce pilots’ night vision. From Helicopters There are two sources of light emissions from helicopters. One source is navigation lights. These lights are on at all times that helicopters are operating. They are similar to fixed-wing aircraft navigation lights as there is a red light on one side and a blue light on the other. There is also a flashing red or white light. The other source of light from helicopters are landing lights. Most helicopters have a single light used to illuminate a landing area during approach. Generally landing lights are turned on a minute or two before landing. Helicopter landing lights would be similar to fixed-wing aircraft landing lights used to approach Renton Municipal Airport. Glare Glare is not expected to be created by any element of the helipad or aircraft. Landscaping Landscaping is not associated with this proposal.