Nome Airport Runway Safety Area Expansion Project

AKSAS Project No. 61413

PROPOSED ACTION DETAILS

Runway 10-28
The main runway at Nome Airport does not meet FAA safety area standards. The existing safety area is deficient in width but can be brought up to standards along a large portion of the runway length There is no safety area beyond threshold 10 and the graded area beyond threshold 28 is of deficient width and narrows to less than the runway width towards the east end. To improve the safety areas, existing cleared areas along the north and south sides of the runway would be graded to create a 500-ft wide RSA along the entire paved runway, with only minor deficiencies in width on the southwest end. Additionally, threshold RSAs would be constructed at the east and west ends of the runway, respectively.

A 1,000-ft long RSA would be built beyond the eastern end of the runway by grading and extending the existing cleared area to the width practicable without impacting the adjacent Seppala Drive. This RSA would be deficient in width on the south side for 500 ft on the east end to avoid impacts to Seppala Drive and the Snake River (see Figure 2).

A new 190-ft long embankment off the western end of the runway would provide for a 170-ft long RSA equipped with an EMAS. An EMAS is designed to stop an aircraft that overshoots a runway without causing structural damage to the aircraft. It consists of a bed of high-energy absorbing, cellular cement material that is designed to crush under the weight of aircraft and exert deceleration forces on the landing gear.  A 150-ft wide and 135-ft long EMAS arrestor bed would be constructed on the paved RSA surface beyond west threshold, with a set-back/lead-in ramp of 35 ft. The north and south edges of the EMAS bed would slope for 10 ft to allow access for emergency personnel and safe passenger egress from aircraft. The RSA would include a 20-ft wide paved access off the west end of the arrestor bed, a 15-ft wide paved access on the north and south sides, and additional graded area on the north side of the arrestor for maintenance and emergency vehicle access.  The image below shows the EMAS system at the airport in Cordova, Alaska.


The EMAS arrestor bed is visible at the end of the runway at the Merle K. (Mudhole) Smith Airport in Cordova, Alaska (DOT&PF file photo).


The EMAS arrestor bed is visible at the end of the runway at the Merle K. (Mudhole) Smith Airport in Cordova, Alaska (DOT&PF file photo).

 

This alternative would result in the extension of the western embankment into the Snake River and would therefore require realignment of a segment of the river further west to accommodate the extension (Figure 2). The river would be realigned between approximately river miles (RMs) 2.1 and 2.3 and routed around the RSA expansion area in a new 900-ft long channel. A ditch on the north side of the main runway would be improved and water would continue to flow from the drainage to the Snake River as it does at present. The design of the realigned Snake River channel would be based on maintenance of the cross-sectional area of the existing channel in this area, in order to mimic the existing hydraulic regime of the river. Therefore, the new channel would have cross-sectional geometry, and flood flow and spring breakup ice flow conveyance characteristics similar to those of the existing river.
This alternative would comply with the congressional mandate to improve RSAs in accordance with FAA standards to the greatest extent practicable by providing a 1,000-ft long RSA on the east end of the runway and a 170-ft long RSA equipped with an EMAS on the west end of the runway. The Proposed Action would require acquisition of land and realignment of the Snake River for the west end RSA expansion. The Proposed Action would avoid impacts to the adjacent Seppala Drive at the east end of RW 10-28, and allow preservation of the existing instrument approach procedures.

Crosswind Runway 3-21
The crosswind runway does not meet FAA safety area design standards. The existing RSA is deficient by 200 ft in width and lacks safety area beyond either threshold. To improve these deficiencies, the RSA would be widened to the standard 500 ft except on the south end of the runway where it would follow the existing embankment to avoid additional impacts to the Snake River. Thresholds would be shifted 600 ft to the north for Runway 3 operations, providing a 600-ft non-standard RSA south of the shifted RW 3 threshold. The safety area on the north end would then be extended beyond the new Runway 21 threshold by 1,000 ft. Shifting the runway thresholds 600 ft north would also correct an existing FAA Flight Standards deficiency by eliminating airspace obstructions, and ensuring that night time approach procedures for RW 3 would continue. Threshold 21 would be displaced to maintain its existing approach and continue use of existing NAVAIDS which are impracticable to move for Runway 21 operations. The NAVAIDs for RW 3 would be relocated and the new 600-ft runway and shoulder surface would be paved due to the threshold shift. This proposed action would also require relocation of a segment of Construction Road, part of the Center Creek channel and a segment of a water utility line (see below). The existing drainage ditch west of the crosswind runway would also need to be moved further west to allow widening of the safety area. Approximately 280,000 cubic yards of excavated material would be generated from the threshold shift and RSA extension.  Usable material would be placed as fill on the new embankments of the main and crosswind runways. Unused excavated material would be stored in a DOT&PF stockpile area proposed as part of the project (see below). 

Utility Relocation
Extension of the crosswind runway embankment to the north would require relocation of the Nome Joint Utility Water Line that currently runs along the existing Construction Road and east of the crosswind runway.  The utility would be realigned to allow construction of this project. 

Drainage Improvements
Center Creek currently flows towards the northern threshold of the crosswind runway from the east and then flows to the south within a ditch that follows the eastern border of airport development. The creek joins the Snake River near RM 0.5.  The existing ditch fills with thick deposits of aufeis (body of layered ice) during winter months, which creates a safety hazard for the crosswind runway and poses an airport maintenance issue.  Furthermore, it is necessary that the proposed crosswind runway embankment extension be constructed at a lower elevation than the existing ditch and it would therefore be at risk of flooding during periods of high flow within the creek. Improvements to the ditch and access for maintenance are needed to resolve the aufeis and prevent flooding problems.  Center Creek and the existing dike on its west side would be shifted east to provide a buffer between the waterway and the new crosswind embankment. A road immediately west of the rerouted ditch would provide access for aufeis management. A 10 ft tall dike would be constructed along the northern 900 feet of the ditch to ensure that flow and aufeis is routed away from airport surfaces. The rerouted stream would rejoin the existing conveyance just southeast of the existing Runway 21 threshold.  Additional drainage improvements along the creek would be necessary near the threshold 28 end of the proposed main runway safety area to move the drainage away from the area that would be filled by the proposed embankment extension and to reestablish the ditch to connect flow to the Snake River.

Construction Road Relocation
Part of Construction Road north of the existing threshold 21 would need to be relocated to allow for the crosswind runway RSA expansion and threshold shift.

Stockpile Area
A stockpile area is needed near the airport to provide a storage area for material (clean fill and organics) generated from excavation associated with the various components of the Proposed Action.  Clean fill could be used for airport maintenance and operational needs and possibly for other projects identified in the Airport Master Plan. The size of the stockpile area would be approximately 1,146 ft by 825 ft.  Material could be stacked to a height of 15 feet.  Location of the stockpile is shown on Figure 2.  The location is compatible with the Airport Master Plan and the Airport Layout Plan (ALP).

 

Nome Airport Existing Conditions

Figure 1 - Click here for larger PDF view

Nome Airport Proposed Action

Figure 2 - Click here for larger PDF view