Attachment J-4 ANC ATCT TRACON BOD Final.pdf

ANC New ATCT and TRACON/Base Building Basis of Design Report – Final Design

June 11, 2024

Prepared for:

Federal Aviation Administration Contract No. 697DCK-22-C-00190

Prepared by:

Stantec Architecture Inc.

725 East Fireweed Lane Anchorage, Alaska 99503

ANC NEW ATCT AND TRACON/BASE BUILDING BASIS OF DESIGN REPORT – FINAL DESIGN

i

Table of Contents

1.0 INTRODUCTION ............................................................................................................ 1.1

1.1 SUMMARY OF WORK ................................................................................................... 1.1

1.2 ATCT SITING ................................................................................................................. 1.1

1.3 LEASE AGREEMENT .................................................................................................... 1.1

1.4 CONTROL CAB SIMULATION ...................................................................................... 1.2

1.5 TRACON BASE BUILDING & LINK ............................................................................... 1.2

1.6 PHYSICAL SECURITY .................................................................................................. 1.2

2.0 CIVIL DESIGN BASIS ................................................................................................... 2.1

2.1 CIVIL DESIGN ASSUMPTIONS/PARAMETERS........................................................... 2.1

2.1.1 Permitting ..................................................................................................... 2.1

2.1.2 Surveying ...................................................................................................... 2.2

2.2 SITE DESCRIPTION ...................................................................................................... 2.2

2.2.1 Site/Utilities Layout and Design .................................................................... 2.2

2.2.2 Grading ......................................................................................................... 2.3

2.2.3 Parking Areas ............................................................................................... 2.3

2.2.4 Heated Parking/Sidewalks ............................................................................ 2.3

2.2.5 Access Safety and Efficiency ....................................................................... 2.4

2.2.6 Snow Removal ............................................................................................. 2.4

2.2.7 ATCT Maintenance ....................................................................................... 2.4

2.3 GEOTECHNICAL ........................................................................................................... 2.4

2.3.1 Soil and Groundwater Conditions ................................................................. 2.4

2.3.2 Site Civil ........................................................................................................ 2.6

2.4 TRAFFIC/SITE ACCESS ............................................................................................... 2.7

2.4.1 Security ......................................................................................................... 2.7

2.4.2 Emergency Vehicle Access .......................................................................... 2.8

2.5 SUBSURFACE UTILITIES ............................................................................................. 2.8

2.6 STORM WATER MANAGEMENT................................................................................ 2.10

2.6.1 Storm Drainage Study ................................................................................ 2.10

2.6.2 Landscaping ............................................................................................... 2.10

2.7 CONTRACTOR FACILITIES ........................................................................................ 2.10

2.7.1 Construction Parking, Staging, and Haul Routes ....................................... 2.10

3.0 ARCHITECTURAL DESIGN BASIS .............................................................................. 3.1

3.1 ARCHITECTURAL DESIGN ASSUMPTIONS/PARAMETERS ..................................... 3.1

3.1.1 Building Codes ............................................................................................. 3.1

3.1.2 Building Functionality .................................................................................... 3.1

3.1.3 Space Programming/ Site Adaptation .......................................................... 3.1

3.2 ARCHITECTURAL DESIGN – COMPATIBILITY ........................................................... 3.2

3.2.1 Aesthetics ..................................................................................................... 3.2

3.3 ATCT ARCHITECTURAL DESIGN ................................................................................ 3.3 ii

3.3.1 ATCT Shaft ................................................................................................... 3.3

3.3.2 ATCT Upper Levels ...................................................................................... 3.3

3.3.3 ATCT Cab ..................................................................................................... 3.4

3.4 TRACON BASE BUILDING & LINK ARCHITECTURAL DESIGN ................................. 3.5

3.4.1 Link ............................................................................................................... 3.5

3.5 BUILDING ENVELOPE .................................................................................................. 3.6

3.5.1 Exterior Finishes ........................................................................................... 3.6

3.5.2 Analysis ........................................................................................................ 3.6

3.5.3 Wall Systems ................................................................................................ 3.7

3.5.4 Roof Systems ............................................................................................... 3.8

3.5.5 Lightning Protection ...................................................................................... 3.9

3.5.6 Façade Maintenance & Fall Protection ......................................................... 3.9

3.5.7 Below Grade Systems ................................................................................ 3.10

3.5.8 Openings .................................................................................................... 3.10

3.6 INTERIOR DESIGN ..................................................................................................... 3.10

3.6.1 Acoustics .................................................................................................... 3.11

3.7 VERTICAL CIRCULATION .......................................................................................... 3.11

3.7.1 Stairs .......................................................................................................... 3.11

3.7.2 Elevators ..................................................................................................... 3.12

4.0 STRUCTURAL DESIGN BASIS .................................................................................. 4.13

4.1 CODES AND REFERENCES ...................................................................................... 4.13

4.2 MATERIALS ................................................................................................................. 4.13

4.2.1 Cast-in-Place Concrete .............................................................................. 4.14

4.2.2 Reinforcing and Tendons for Cast-in-Place Concrete ................................ 4.14

4.2.3 Structural Steel ........................................................................................... 4.14

4.2.4 Steel Decking ............................................................................................. 4.15

4.2.5 Reinforced Masonry ................................................................................... 4.15

4.3 DESIGN LOADS .......................................................................................................... 4.15

4.4 LOAD COMBINATIONS ............................................................................................... 4.20

4.5 SERVICEABILITY ........................................................................................................ 4.21

4.5.1 Vibrations .................................................................................................... 4.21

4.5.2 Future Expansion ....................................................................................... 4.22

4.5.3 Durability ..................................................................................................... 4.22

4.6 SEISMIC DESIGN CRITERIA ...................................................................................... 4.22

4.6.1 Performance Based Design (Tower) .......................................................... 4.23

4.6.2 Hazard Levels and Performance Goals ...................................................... 4.23

4.6.3 Hazard Determination ................................................................................. 4.25

4.6.4 Analysis and Modeling (Tower) .................................................................. 4.25

4.6.5 Supplementary Procedures (Tower) ........................................................... 4.27

4.6.6 Acceptance Criteria: Elements (Tower) ...................................................... 4.27

4.6.7 Analysis and Modeling (TRACON) ............................................................. 4.37

4.7 WIND DESIGN CRITERIA ........................................................................................... 4.38

4.7.1 Tuned Mass Dampers (TMDs) ................................................................... 4.38

4.8 GEOTECHNICAL CRITERIA ....................................................................................... 4.38 iii

5.0 MECHANICAL DESIGN BASIS .................................................................................... 5.1

5.1 MECHANICAL DESIGN ASSUMPTIONS/PARAMETERS ............................................ 5.1

5.1.1 Codes/References ........................................................................................ 5.1

5.1.2 Design Weather Data ................................................................................... 5.1

5.2 CALCULATIONS ............................................................................................................ 5.2

5.3 HEATING AND COOLING LOADS ................................................................................ 5.2

5.4 HEATING, VENTILATION, AND AIR CONDITIONING (HVAC) DESIGN ..................... 5.3

5.4.1 Boilers ........................................................................................................... 5.3

5.4.2 Heating System ............................................................................................ 5.4

5.4.3 Chillers .......................................................................................................... 5.5

5.4.4 Cooling System ............................................................................................ 5.5

5.4.5 Ventilation System ........................................................................................ 5.5

5.5 ATCT STAIR PRESSURIZATION SYSTEM .................................................................. 5.7

5.6 CENTRAL VACUUM SYSTEM ...................................................................................... 5.8

5.7 BUILDING CONTROLS ................................................................................................. 5.8

5.8 DOMESTIC WATER SYSTEM DESIGN ........................................................................ 5.8

5.8.1 Domestic Water Pressure Requirements ..................................................... 5.8

5.9 PLUMBING SYSTEMS .................................................................................................. 5.9

5.9.1 Water Conservation ...................................................................................... 5.9

5.9.2 TRACON Plumbing Fixtures ......................................................................... 5.9

5.9.3 ATCT Plumbing Fixtures ............................................................................ 5.10

5.9.4 Domestic Water Heating ............................................................................. 5.10

5.10 STORM DRAINAGE DESIGN ...................................................................................... 5.10

5.11 FUEL OIL SYSTEM DESIGN ....................................................................................... 5.11

6.0 ELECTRICAL DESIGN BASIS .................................................................................... 6.12

6.1 DESIGN ASSUMPTIONS/PARAMETERS................................................................... 6.12

6.2 NORMAL POWER DISTRIBUTION SYSTEM ............................................................. 6.13

6.3 EMERGENCY POWER SYSTEM ................................................................................ 6.21

6.4 GENERAL WIRING PROVISIONS .............................................................................. 6.24

6.5 LIGHTING SYSTEMS .................................................................................................. 6.25

6.6 FIBER-OPTICS COMMUNICATION TRANSMISSION SYSTEM ................................ 6.27

6.7 INFORMATION AND COMMUNICATIONS SYSTEM ................................................. 6.29

6.7.1 Outside Cable Plant .................................................................................... 6.29

6.7.2 Inside Cable Plant ...................................................................................... 6.29

6.7.3 Audiovisual / Paging ................................................................................... 6.30

6.7.4 Public Safety Distributed Antenna System Supported Radio Systems ...... 6.30

6.8 GROUNDING ............................................................................................................... 6.31

6.9 SKM SYSTEM ANALYSIS ........................................................................................... 6.32

7.0 FIRE PROTECTION AND LIFE SAFETY ...................................................................... 7.1

7.1 DESIGN ASSUMPTIONS/PARAMETERS..................................................................... 7.1

7.2 OCCUPANCY USE GROUP .......................................................................................... 7.2

7.3 OCCUPANT LOAD AND EGRESS CALCULATIONS ................................................... 7.2

7.3.1 Occupant Load ............................................................................................. 7.2 iv

7.3.2 Exit Capacity ................................................................................................. 7.8

7.3.3 Travel Distances ........................................................................................... 7.9

7.3.4 Exit Discharge ............................................................................................ 7.10

7.4 TYPE OF CONSTRUCTION ........................................................................................ 7.10

7.4.1 Required Fire-Resistance Ratings of Building Elements ............................ 7.11

7.5 ACCESSIBILITY REQUIREMENTS ............................................................................ 7.12

7.6 FIRE PROTECTION, DETECTION AND ALARM ........................................................ 7.12

7.6.1 Fire Alarm ................................................................................................... 7.12

7.6.2 Fire Suppression ........................................................................................ 7.16

7.6.3 Fire Command Center ................................................................................ 7.18

7.7 SMOKE ENCLOSURE/CONTROL SYSTEMS ............................................................ 7.18

7.8 FIRE HYDRANT FLOW TEST DATA........................................................................... 7.20

8.0 PROJECT SCHEDULE AND COST ESTIMATE ........................................................... 8.1

8.1 DESIGN SUBMITTAL MILESTONES ............................................................................ 8.1

8.2 COST ESTIMATE .......................................................................................................... 8.1

APPENDIX A BUILDING RENDERING ................................................................................ A

LIST OF TABLES

Table 2-1. Anticipated Permits ................................................................................................... 2.1 Table 2-2. Utility Connections and Relocations ......................................................................... 2.8 Table 4-1. General Acceptance Criteria ................................................................................... 4.31 Table 6-1. Facility Calculated Demand Load ........................................................................... 6.13 Table 7-1. Occupancy Classification Summary ......................................................................... 7.2 Table 7-2. Occupant Load Calculation – TRACON /Base Building ........................................... 7.3 Table 7-3. Occupant Load Summary – ATCT ............................................................................ 7.5 Table 7-4. Description of Construction Type .............................................................................. 7.8 Table 7-5. Travel Distances ....................................................................................................... 7.9 Table 7-6. Description of Construction Type ............................................................................ 7.10 Table 7-7. Required Fire-Resistance Ratings .......................................................................... 7.11 Table 7-8. Opening Fire Protection Assemblies, Rating and Markings ................................... 7.19 Table 8-1. Design Packages Submitted ..................................................................................... 8.1

LIST OF FIGURES

Figure 4-1: Site-specific spectra at MCEr, DBE and SLE ........................................................ 4.18 Figure 4-2. Ground motions used for MCEr analyses and MCEr target spectra .................... 4.19 Figure 6: CT ENCLOSURE ...................................................................................................... 6.18 Figure 7: PANEL SESHA ......................................................................................................... 6.19 Figure 8: PANEL SESHB ......................................................................................................... 6.20 Figure 9: PANEL SEDSH ......................................................................................................... 6.21 Figure 10: PANEL GSHB ......................................................................................................... 6.22 Figure 7-1: Fire Flow Map ........................................................................................................ 7.20

INTRODUCTION

1.1

1.0 INTRODUCTION

1.1 SUMMARY OF WORK

The Federal Aviation Administration (FAA) has contracted for the design of a new Airport Traffic Control Tower (ATCT) and Terminal Radar Approach Control (TRACON) Base Building at the Ted Stevens Anchorage International Airport (ANC) in Anchorage, Alaska. The existing ATCT was constructed in 1977 and designed to accommodate four operational positions. Current operations require eight operational positions to serve both ANC and the Lake Hood Seaplane Base (LHD). This condition of overcrowding has resulted in controllers working in suboptimal positions.

The existing TRACON Base Building was also constructed originally in 1977 and later enlarged and modified with several additions and renovations, resulting in a confusing interior layout. Its exterior envelope is not meeting modern energy codes, its physical plant is inefficient and obsolete, and its interiors are dated. The existing site is extremely tight and abuts the general public parking garage and landside drop off and pick up aisles, which creates a security hazard. The existing terminal radar approach control facility and equipment rooms are undersized and contain obsolete equipment.

Amendment 11 clarifies that the demolition plans of the existing tower and terminal radar approach control facility are not included in the design Scope of Work (SOW) and that the FAA maintains an Asbestos Compliance Dashboard.

1.2 ATCT SITING

The ATCT was sited based on an extensive site selection process undertaken by the FAA. The ATCT siting report was provided by the FAA to the design team. The site was selected based on a) available spaces large enough to accommodate the program that could be purchased or leased by the FAA, b) required visibility of aircraft approaches to both LHD and ANC, and c) the increased traffic in the northern portion of the airport due to the exponential increase in cargo traffic since the existing ATCT’s completion in 1977. The Siting Report provided a) an exact geo-location/ coordinate points for the center point of the new ATCT’s Cab, b) an exact orientation angle from true north of the Cab controller positions, with a required layout of the controller positions, c) an exact required eye height for the Cab controllers, and d) a maximum ATCT height.

1.3 LEASE AGREEMENT

The FAA will agree to a long-term lease with the State of Alaska Department of Transportation and Public Facilities (DOT&PF), who owns the land that ANC sits on. Stantec will be providing a legal description of the lease boundary to FAA to support their lease agreement coordination with the State.

1.2

1.4 CONTROL CAB SIMULATION

The FAA performed extensive cab simulations as part of the siting study that preceded this project. These were 3-D simulations showing the site lines from the ATCT to key areas of ANC and LHD. This proved that the MAL-ATCT could be used with some revisions, oriented per the siting study. This aspect of the pre-planning was done without Stantec involvement; however, we were shown slides from the simulation and given the siting study as a resource. The evolved Cab design has since been re-simulated by the FAA. This simulation resulted in the FAA accepting the current cab design and the mullion sizes. The subsequent accommodation of the running of utilities in the mullions has resulted in a slightly increased mullion size, which has been accepted by the FAA. One result of the simulation was that the Lake Hood Landing Controller LC(LH) position and the Anchorage Landing Controller LC(ANC) swapped places with what had been open consoles to improve their controller site lines.

1.5 TRACON BASE BUILDING & LINK

The project includes a TRACON Base Building to accommodate a medium activity level TRACON as well as staff and environmental support functions for the TRACON and ATCT. This includes administrative office spaces and office support spaces such as mail/copier room, breakroom, and conference rooms.

Our design incorporates the Link between the ATCT and the TRACON Base Building as an integral part of the Base Building, forming a “podium” for the ATCT. The Link and the ATCT are separated from one another by a fire-area/building-construction-type and seismic/expansion joint separation.

1.6 PHYSICAL SECURITY

The project is required to meet the FAA’s electronic and physical security requirements. There are three primary elements to the security of the facility: 1) electronic monitoring and alarms, 2) site security, and 3) building security.

The first, electronic monitoring and alarms, is integral to the other two using sensors, alarms, and cameras. See the electronic security section of Part 7 of this document for more details.

The second, site security, is being accounted for primarily by the perimeter site barrier to control access onto the site and prevent intrusions by non-allowed persons or vehicles. See the site security section of Part 2 of this document for more detail on the site security.

The third, building security, is handled by secure entries into the building using keys and card readers where appropriate. Guests are only allowed to enter thru the main entry, which has an arctic entry with the interior door being locked with an electronic lock that can be remotely unlocked, and a voice communication system with both the Level 1 reception area and Level 2 admin personnel. They will also have physical and electronic views into this secure vestibule from the interior. Only visitors that have been identified will be allowed in, first at the perimeter gates, and second through this main entry. Because of this level of security, and because it is not typically accessed by the public, there is no FAA requirement for features such as security guards, metal detectors, or x-ray machines. Visitors get “buzzed-in,” then sign in and get visitor badges with varying levels of access allowed, depending on what they are there to

1.3 do (some require constant supervision while on site, others may get to work alone in certain rooms). The ATCT controllers and TRACON controllers only have access to their own controlled work areas as well as areas of the building open to all employees, such as the break rooms and restrooms. Certain staff members such as high-level administrators and facility maintenance support will have access to all areas.

CIVIL DESIGN BASIS

2.1

2.0 CIVIL DESIGN BASIS

2.1 CIVIL DESIGN ASSUMPTIONS/PARAMETERS

The civil design focuses on efficiency for daily operations and maintenance, as well as a forward-thinking approach to impacts on future design. Our team’s siting for the two-story TRACON considers efficient site flow, minimizing utility impacts, and environmental/cold regions engineering factors.

2.1.1 Permitting

Various permits will be needed prior to construction of the new facility and include the anticipated permits found in Table 2-1.

Table 2-1. Anticipated Permits

Required Permit (Responsible Party)

Typical Review Period

Schedule/Project Impacts

National Environmental Policy Act (NEPA) Environmental Assessment (FAA)

45 days • Preparation and review of the NEPA document is anticipated to be completed by FAA prior to 70% so all environmental commitments can be captured by the design prior to the budget review.

FAA Form 7460-1 Notice of Proposed Construction of Alternation

(FAA)

45 days • Will be filed through FAA’s Obstruction Evaluation/Airport Airspace Analysis OE/AAA portal.

• During the ATCT Site Selection Analysis, the FAA air spaced the proposed ATCT development via the 7460 process.

Anchorage Water and Wastewater Utility (AWWU) Mainline Extension or Intergovernmental Agreement (A/E)

• For plan review of the main line relocation of the 16-inch water. Will be coordinated as a Private Development with

AWWU

AWWU Water and Sewer Connect Permits (A/E)

3 weeks • For plan review and permitting of water and sewer utility connections.

Alaska Department of Environmental Conservation (ADEC) Separation Waiver Review Permit (A/E)

30 days • Required for relocation of the 16-inch water main crossing of the 16-inch sanitary and storm sewer mains.

• Per AWWU, no separate Drinking Water Plan review will be required for the main line relocation.

Municipality of Anchorage (MOA) Building Permit (A/E)

30-45 days • Will include stormwater review, MOA Fire Review, Zoning, Right-of-Way, structural, electrical, and mechanical review.

DOT&PF Driveway Permit (A/E)

3 weeks • Review of driveway locations connecting to state roads

• Verify DOT&PF driveway standard conformance.

• Per DOT&PF Right of Way, this permit is issued by ANC

Engineering with their Building Permit process.

Ted Stevens Anchorage International ANC Building Permit (FAA) after MOA Building Review (A/E)

4 weeks • Last step in permitting process after MOA.

2.2

Required Permit (Responsible Party)

Typical Review Period

Schedule/Project Impacts

• Requires submission of plans with permit approvals or applications for MOA Building Permit, MOA Fire Approval, ADEC permits, and FAA 7460-1.

Construction Safety and Phasing Plan (CSPP) per FAA Advisory Circular 150/5370-2 Operational Safety on Airports During Constuction (A/E)

45 days • Draft prepared as part of the 70% submittal.

• Required for all work within the airport operations area fence line. (FOTS).

• Reviewed by all FAA lines of business.

• Contract enforceable document and contractors are required to prepare a Safety Plan Compliance Document to demonstrate their means and methods are in accordance with the CSPP requirements.

• FAA ATO may require a Safety Risk Mitigation (SRM) to be held with ANC and stakeholders for interproject coordination.

Traffic Plan • As part of the ANC Building Permit

Storm Water Pollution Prevention Plan (SWPPP)

• ADEC Division of Water Quality

• Prepared by contractor under Alaska Pollutant Discharge

Elimination System (APDES) requirements.

• Erosion and Sediment Control Plan (ESCP) prepared for this project will be template document for SWPPP prepared by the contractor.

• ANC is covered under the ANC General Permit (ANC-GP) issued September 25, 2019, as AKR061000 for all industrial facilities working at the airport replacing the airports Multisector General Permit (MSGP).

2.1.2 Surveying

A site survey was performed by Stantec in September 2022 for both the ATCT/TRACON site as well as the fiber optic transmission system (FOTS) loop on the airfield. The Alaska Zone 4 State Plane coordinate system and NAVD88 datum were used. This survey located existing utilities, property boundary, and grades so conflicts could be resolved early in the project with the FAA, ANC, or the utility owner.

2.2 SITE DESCRIPTION

2.2.1 Site/Utilities Layout and Design

FAA’s Anchorage ATCT Siting Study defined the ATCT location with the center point of the cab fixed at North 61 10’ 53.1854”, West 149 59’ 13.6695” (NAD83) and cannot deviate more than five feet in any direction from this position. This building is oriented in a north–south direction to the west of the ATCT and connected to the ATCT base.

Access is from the north by De Havilland Avenue going efficiently through the site to the second access drive at Postmark Drive. A service yard north of the building provides access for a standard 24-foot box truck to the loading dock, as well as access to garbage and recycling dumpsters, the utility enclosure, where the emergency generator fuel tank, switch gear and transformer will be located. De Havilland

2.3

Avenue provides access to the drive through aisle for a WB-50 tractor trailer truck, and fire apparatus for emergency response.

Most utilities serving the building will extend from De Havilland Avenue. In addition to standard utility needs, we will relocate existing utilities from under the building. Details on connections and relocations can be found in Table 2-2. Utility Connections and Relocations.

2.2.2 Grading

New site grading will maintain existing grades and drainage patterns to minimize additional earthwork.

The existing site contours are relatively flat since the site is currently being used for general aviation aircraft parking tie downs. Parking grades are required to be 1% to 3% longitudinally and transversely, except at the accessible spots where they will meet the Architectural Barriers Act (ABA) accessibility standards. Some drive lanes cross slope exceed 3% but not more than 5% to allow proper drainage, but not in parking locations. Since the existing maximum grade of half of the site is 0.5%, some filling will be necessary to meet the 1% minimum.

Due to a 6-foot elevation change between the site and Postmark Drive at the southeast corner of the site, the Postmark Drive access drive will be excavated to meet DOT&PF Driveway Standards to include a 10-foot landing at bottom with a maximum grade of 2% and a longitudinal driveway grade not to exceed 5%.

Per the SOW, the finished floor elevation of the new TRACON and ATCT is 96 feet mean sea level (MSL). The grade at the building wall around the vegetated sides of the building is six inches below the finished floor elevation and slope away from the building at 5% for 10 feet to confirm positive drainage.

Where sidewalks border the building wall slopes, ABA requirements are maintained leading to doors.

2.2.3 Parking Areas

As shown on the site layout, the design provides 120 spots total with 4 accessible spots (1 van accessible spot), 14 spots for government vehicles (not annotated), 102 spots for employees (2 stalls designated for motorcycle parking). Stalls are 9 feet wide by 20 feet long and have engine block heater outlets. The parking stalls fronted by a sidewalk were shortened to 18 feet and the sidewalk increased from the minimum 4 feet width to 6 feet to account for vehicle overhang per MOA code. This allows the blocker heater outlets to remain out of the accessible pathway. The government vehicle parking spots are provided at two locations on the site, with 12 along the west fence line at the north entrance and 2 spots near the loading dock at the north end of the building. The access drive through the parking areas is 26-feet wide to facilitate emergency vehicle access. No wheel stops are provided to allow for ease of snow removal operations.

2.2.4 Heated Parking/Sidewalks

Heated accessible parking and sidewalks are provided to the front doors of the base building, and at the loading dock directly beneath the building overhang. The parking pad for accessible parking is concrete due to the construction methods for the heating systems. All sidewalks are concrete with appropriate accessible grades complying with ABA requirements.

2.4

2.2.5 Access Safety and Efficiency

The drive access at De Havilland Avenue and Postmark Drive provides two alternatives to the site. Traffic volume is very low and isolated to local traffic accessing the ANC Safety Building, Menzies Aviation, and the ANC Field Maintenance. Postmark Drive is a main throughfare through the airport for access from the cargo facilities like FedEx and UPS on the north end of the airfield and the airport Post Office. During times of high traffic on Postmark Drive, especially if it is dark with icy conditions, staff may decide to enter via the De Havilland gate. The intersection of Postmark Drive, the Postmark gate, and Tom Wardleigh Drive is lit by streetlights. Therefore, vehicles entering and exiting the site are more visible in the dark winter months and vehicles accessing the site have over 60 feet to the gate card reader to pull off the road to avoid potential rear end accidents.

2.2.6 Snow Removal

Efficient snow removal on the site is a critical consideration for Alaskan facilities. Due to the size of the site, long-term snow storage is not feasible. Temporary snow stacking within the parking lot on off peak hours and haul off as currently performed at the existing Tower facility will be required. The site provides a long, straight parking layout without wheel stops to allow for safe and efficient plowing and stacking snow at the ends of the drive. The wide access drive allows side by side access for dump trucks and front-end loaders for snow haul off. The strongest winds in Anchorage either come out of the north or the south. When the winds come from the south, they are normally Chinook winds and are warm and tend to melt the snowpack around the city. Winds from the north are generally associated with a winter storm and can blow snow around the site. When the winds stall behind a structure, it drops the snow it had levitated into hardpacked snow drift piles that can block means of egress. The building is oriented, so the narrow part of the building is pointed into the wind to minimize the size and the formation of any drifting on the lee side of the building, keeping doors free from blocking and easier snow removal effort.

2.2.7 ATCT Maintenance

In addition to the façade access system, a crane may be needed for maintenance on the ATCT and other facilities for the TRACON. The access drive allows crane setup at the base of the ATCT or west side of the building without the need for excessive turning movements. Dual access gates for the site will maintain traffic flow no matter where the crane is set up.

2.3 GEOTECHNICAL

2.3.1 Soil and Groundwater Conditions

2.3.1.1 General Soils

A Geotechnical Engineering Report is being prepared by Shannon & Wilson, Inc. (S&W), 5430 Fairbanks Street, Suite 3, Anchorage, Alaska. The report will describe the field explorations, laboratory testing, site conditions, geotechnical conditions, and groundwater conditions. The report will contain recommendations for structural foundations, pavement, earthwork, surface drainage, and seismic design

2.5 of the site. Field explorations have been completed, consisting of ten borings, shear wave velocity profiling, cone penetrometer tests (CPTs), and ground resistivity measurements. Six, 20-foot borings have been completed around the buildings in areas for pavement and utilities. Deeper borings were completed within the building footprints including a 190-foot boring at the ATCT location, one 100-foot boring at the northwest corner of the TRACON, and two 50-foot borings at the northeast and southwest corners of the TRACON. CPTs were conducted near the northwest and southwest corners of the TRACON with one additional CPT near the southeast corner of the TRACON.

The near surface conditions consist of an assemblage of gravel, sand, and silt fills over peat. Fills typically extend down to approximately 8 to 9 feet below the ground surface (bgs) with peat soils encountered to 13 to 15 feet bgs. Below the peat, borings encountered silt and clay to approximately 30 to 33 feet with soils transitioning to silt and silt with sand to the full depth explorations. In the upper 30 feet of the borings, soils were general medium dense and native silts and silt with sand were uniformly dense to very dense.

2.3.1.2 Groundwater

Our explorations suggest that groundwater in the project area is sporadic and was not encountered consistently in our borings. In borings where groundwater was encountered, it was found approximately 8 to 12 feet bgs. Based on results from our borings and our experience in the general area, static groundwater will likely be encountered at approximately 5 to 10 feet below the ground surface.

Groundwater will likely have a significant impact on construction because of the likely presence of pockets of clean (low fines content) sand and gravel within the fill will yield rapid inflow of groundwater into excavations once penetrated. Similar conditions could be experienced if layers of permeable native soils are penetrated below layers of thinner fill horizons. Inflow of groundwater will present the opportunity for temporarily unstable excavation conditions and necessitate dewatering until those lenses are drained.

The duration of groundwater inflow will depend on the thickness and horizontal extent of the water bearing layer, which could be significant if such a layer is encountered below the fill materials.

2.3.1.3 Contamination

The Environmental Site Assessment conducted at the site suggests significant soil and groundwater contamination is likely not present within the limits of the ATCT and TRACON site. Analytical results from the site assessment indicate that per- and polyfluoroalkyl substances (PFAS) and perfluorooctanoic acid (PFOA) analytes are present, but at concentrations that are generally below cleanup levels. We understand that ADEC has expressed no objection to use of excavated materials as fill on site. However, earthwork required for this project will generate excess soils or soils that are not suitable for use as backfill (such as organic material) that will need to be disposed off-site. Even though PFAS/PFOA concentrations are below cleanup levels, finding a place that will accept soils with any amount of these contaminants can be challenging. Soil disposal options will range from depositing soil at the airport’s soil disposal site or transferring to a third party for remediation or shipment to an off-site disposal facility.

2.6

2.3.1.4 Seismicity

Due to the earthquake prone nature of south-central Alaska, the new facilities will be designed to accommodate significant ground motions. A project-specific probabilistic hazard analysis (PSHA) is being conducted to provide source ground motions using the most up to date science. The severity of seismic hazard risk at the site has been determined based on site-specific explorations and geotechnical engineering analysis. Deep explorations were conducted to allow direct measurement of shear wave velocities and development of a subsurface soil and shear wave velocity profile that was used to evaluate seismic site response and development of site-specific response spectra. The site response was used to evaluate and quantify the seismic hazard risks, evaluate soil-structure interaction, and contribute to the structural design component of the project. Our explorations indicate the presence of potentially liquefiable soils in the upper approximately 18 feet bgs.

2.3.1.5 Foundations

Because of the issues with site contamination, structure type, and soil conditions, deep foundations were the preferred foundation alternative for supporting the new ATCT and TRACON. Locally, driven piles are the most viable deep foundation option in terms of material availability and contractor experience. We evaluated other deep foundation alternatives, such as drilled shafts, to determine the most cost effective and efficient way to support the facilities.

2.3.2 Site Civil

Site soil and water challenges impact excavations for utilities. Near surface soils are frost susceptible and variable, so pavement structural sections were designed to accommodate these conditions. Typically, variable subgrade conditions under pavements are mitigated by using a thick structural section to reduce the seasonal frost penetration into frost susceptible soils. However, given the contamination concerns, alternatives, such as insulated sections or the use of geosynthetics, to reduce the amount of earthwork needed to provide stable and reliable pavement support were evaluated.

2.3.2.1 Pavement Design

Pavement was designed consistent with S&W geotechnical recommendations. Materials will meet the requirements of DOT&PF Standard Specifications for Highway Construction. While most traffic accessing the site will be personal vehicles, the design was controlled by the heavy structural fire pumper and ATCT ladder apparatus. Cranes that will typically be used for maintenance on the tower will likely be multi-axled tired, with telescoping hydraulic booms. These cranes are meant to be operated on DOT&PF maintained roads over H20 rated structures. Once on site, any necessary counterweights can be added as needed for crane heights and weights to be lifted. The counterweights can be as much as 300,000 pounds in addition to the 120,000 pound weight of the crane when driven on the road.

The typical pavement section for this type of development consists of hot mix asphalt and 4 inches of crushed base course over a 30-inch layer of non-frost susceptible subbase fill to minimize frost penetration. Aprons for heated accessible spots will be concrete with transition zones using either

2.7 variable subbase thicknesses or insulation to reduce the effects of differential seasonal movement, like tripping hazards and long-term fatigue, at the interface between heated and non-heated pavements.

2.3.2.2 Soil Erosion and Traffic Control Plans

During construction, the contractor will be required to prepare a Stormwater Pollution Prevention Plan (SWPPP) to meet the APDES General Construction Permit requirements for soil erosion and submit it through the DEC’s new electronic Environmental Data Management System (EDMS). Stantec will generate this base document with the project critical information and the contractor will fill in the blanks.

As of September 25, 2019, ANC is covered under the ANC General Permit (ANC-GP) issued as AKR061000 for all industrial facilities working at the airport replacing the airport’s Multisector General Permit (MSGP).

Traffic control plans will also be produced by the contractor and will likely consist of truck crossing signs across De Havilland Avenue and the project entrance and at the intersection of De Havilland Avenue and Postmark Drive. The south bound lane of Postmark Drive will occasionally have to be blocked at the Postmark Drive entrance.

2.4 TRAFFIC/SITE ACCESS

2.4.1 Security

The Facility Security Level (FSL) for this facility is categorized as FSL 2. Security measures meet FAA Order 1600.69, FAA Facility Security Management Program. This includes a chain-link fence set 20-feet back from the lease lot line with vertical lift pivot, controlled access gates with card readers at De Havilland Avenue and Postmark Drive.

A 4-foot-wide pedestrian access gate will be provided at the north gate and at the southwest corner of the site. Typically, the 20-foot setback is observed inside the fence line as well, but due to the congestive nature of the site, this criterion cannot be met. Due to ANC’s concerns with the Tug Road being the single access point to the Air Operations Area (AOA) heavily used by tankers, tugs, and various construction traffic, additional lease area is not available on the west side of the lease and only 17 feet can be maintained from the fence line to the west lease lot line. To mitigate this, the existing guardrail along the Tug Road, currently owned by ANC, will be relocated 3 feet to the lease lot boundary. ANC indicated they would remove the existing guardrail with the construction of this project. Additionally, ANC needs to queue construction truck traffic waiting to be escorted through the AOA gate along the fence line and to the south of the project lease lot. To ensure the setback distance is maintained, the guardrail will be extended along the south edge of the fence to the existing grassed area south of the project. This south run of guardrail will meet the 20-foot setback requirement.

The chain-link fence will be 7-feet tall with an additional foot of three strands of barbed wire. The fabric will be barbed-barbed selvage to discourage defeat by overtopping or undercutting the fence line by intruders. Blast design, including walls and crash barriers around the facility, is not required due to FSL 2 categorization.

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2.4.2 Emergency Vehicle Access

Emergency response to the facility during a fire will be answered by the Anchorage Fire Department from Fire Station 5 at the corner of McRae and Spenard Road and supported by ANC Fire from the ANC Safety Building at the west end of De Havilland Avenue. Emergency vehicle access is available through both security gates (De Havilland Avenue and Postmark Drives) with a 26-foot-wide access drive for ATCT ladder and pumper apparatus to traverse the site unimpeded. A knox box will be provided for fire department access through the security gates. Fire access is also provided to the base of the ATCT for the sprinkler riser connections. The Fire Department Connection (FDC) will be located near the main doors of the facility. A single pumper fire hydrant has been located across the driveway from the FDC for fire truck access. A double pumper fire hydrant has been located just inside the north gate to provide the remaining required fire coverage for the opposite side of the building.

2.5 SUBSURFACE UTILITIES

Table 2-2 lists the required utility relocations, construction, and services. Sheet C101, Existing Site and Demolition Plan, shows the existing utilities and those to be removed or relocated to accommodate the new building construction. Sheet C301, Site Plan Layout, shows all new utilities when the site is developed.

Table 2-2. Utility Connections and Relocations

Utility /Owner Connections/Relocation Needs Utility Background and Design Notes

6-inch Ductile Iron (DI) Sewer/AWWU

New service connection. • Connect to existing 16-inch DI Sewer Main that is relocated to the north.

• Main is deep requiring a deep service riser connection.

• Requires AWWU Connect Permit prior to construction.

8-inch DI Water Fire Loop/AWWU

New utility construction. • Connect to existing 16-inch DI Water Main that is relocated to the west. Loop will be connected to the north and south ends of the relocation.

• A new single pumper fire hydrant near FDC at main facility entrance at the southeast corner of the building.

• Valves at service to building will include post indicator valve risers to show open/close status of the valves.

• Requires Private Development Agreement with

AWWU.

8-inch DI Water Service/AWWU

New service connection. • Connect to new 8-inch DI Fire Loop to provide fire flows and domestic water service.

• Servce to building will include post indicator valve riser to show open/close status of the valves.

• Requires AWWU Connect Permit prior to construction.

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Utility /Owner Connections/Relocation Needs Utility Background and Design Notes

16-inch DI Water Main/AWWU

Will be relocated from under proposed TRACON to the east.

• Existing water main is buried 12 feet deep, was built in 1976, and near the end of its life.

• Approximately 530 linear feet (LF) of new DI pipe.

• Will provide service to one double pumper fire hydrant at the northwest corner of the site.

• Must meet AWWU Design Criteria Practice Manual

(DCPM).

• Requires a utility agreement between AWWU and

ANC coordinated by AKDOT&PF-CR Utilities Section.

• Requires a Private Development Agreement with

AWWU.

48-inch Reinforced Concrete Pipe (RCP) Storm Drain/ANC

Will be relocated from under new TRACON to the west under the access drive.

• Constructed in 2012 and buried 10 feet deep.

• Receives runoff from the ditch south of Taxiway V and flows north along Postmark Drive to the Knik Arm of the Cook Inlet.

• Will require 343 LF of new 48-inch RCP and 3 new storm drain manholes.

• New manhole…