GM_21-13.pdf

Memorandum

Western Federal Lands Highway Division 610 E. Fifth Street

Vancouver, WA 98661-3801

Subject: GEOTECHNICAL INFORMATION Reply to: HFL-17

& RECOMMENDATIONS GM21-13

Snug Harbor Road Paving and Bike Trail, AK PFH 59(1) Geotechnical Information and Recommendations

From: Robert Kraig, Geotechnical Engineer Date: October 31, 2014 Geotechnical Services

To: Janice Ritter Project Manager

INTRODUCTION & SCOPE

This memorandum provides geotechnical information and recommendations for the proposed Snug Harbor Road Paving and Bike Trail project located in Snug Harbor, Alaska. The project is located about 100 miles driving distance south of Anchorage in the north-central portion of the Kenai Peninsula, just east of Cooper Landing. A project location map is shown on the following page as Figure 1. The proposed project starts at Station 100+00 at the Sterling Highway and extends to Station 198+16 at the connection of the road leading up to the Senior Center. A project vicinity map is provided as Figure 2.

The project includes repaving an approximately 1.12 mile section of the Snug Harbor Road (currently paved) and reconstructing and paving about 0.72 miles of road that currently has a graveled travel surface for a total project length of about 1.85 miles. It is reported that prior to improvement of the Snug Harbor Road it was used primarily as a logging road. The paved section was reconstructed in 2000/2001 with 2 inches of asphalt concrete pavement over 4 inches of base, and 12 inches of select material underlain by geotextile separation fabric. The 2000/2001 reconstruction plans called for over-excavation of unsuitable subgrade materials, when encountered.

A paved separated bike path beginning at Station 100+00 is proposed to roughly parallel the current paved section for about 0.82 miles and will adjoin the paved section at Station 200+00 (mainline Station 143+44), at which point the bike path will become a paved shoulder that will run along each side of the roadway to the end of the paved section at about mainline Station 216+39. From there the paved shoulder bike lane will travel along each side of the reconstructed roadway to the end of the project at about 338+39. The separated bike path will be 8 feet wide with 2 foot graveled shoulders and 4 feet wide paved shoulders from the end of the separated path to the end of the project. Other aspects of the project include construction of two cast-in-place culvert headwalls to provide additional width at the twin culverts located at 202+15 and drainage improvements. Reported frost heaving will be mitigated from station 304+00 to 306+00.

Figure 1: Project Location map.

Figure 2: Project Vicinity map.

Begin Project

End Project

End Paved Section, Begin Graveled Section

Kenai Lake

PROJECT INVESTIGATION & TESTING

Project site investigation consisted of a site visit and visual reconnaissance in late October 2012 in sub-freezing conditions. Two grab samples, SG-1 and SG-2, were scraped from the cutslopes in the vicinity of 316+00 and at 331+00 as shown below in Photos 1 through 4. The samples were returned to WFLHD for visual and textural assessment with no laboratory testing performed (frozen ground prevented collecting representative samples). No further subsurface investigation was planned or conducted for the project. Project site review included a document search as discussed in the next section plus anecdotal information from the AKDOT & the local road maintenance foreman.

Photo 1: Grab sample SG-1 (bag on left) taken from the cutslope in the vicinity of 316+00.

Photo 2: Grab sample SG-1 (bag on left) taken from the cutslope in the vicinity of 316+00.

Photo 3: Grab sample SG-2 (bag on left) taken from cutslope in the vicinity of 331+00.

Photo 4: Grab sample SG-2 (bag on left) taken from cutslope in the vicinity of 331+00.

SITE CONDITIONS & OBSERVATIONS

Geology and Soils

A document search (desk study) was performed, the results show that the project is located between two broad physiographic provinces—the Kenai Mountains to the east and the Kenai Lowlands to the west. The topography of the peninsula resulted from heavy glaciation and glacial retreat. Active tributary glaciers following the last period of maximum glaciation are still located to the west and south of the project. (Van Patten, 1984)

The soils in the project area formed mainly in alluvium, glacial drift, loess, residuum, and organic material. The alluvium and glacial drift were derived from stratified sedimentary and volcanic rocks:

mainly greywacke, slate, and argillite, with minor conglomerate and volcanic rocks. The loess is probably a mixture of silty material that derived from glacial outwash and volcanic ash. Residuum is generally in the form of angular shale fragments on talus slopes. (Van Patten, 1984)

Grab samples SG-1 and SG-2 underwent visual and textural assessment by the project Geotechnical Engineer. Both samples appear to be of the same material type and origin, and described as gravelly, silty sand with cobbles, or cobbly, silty, sandy gravel. The sand and gravel constituents were both interpreted to grade from very fine to coarse, with the gravel observed to be subround to subangular and of the same rock type (greywacke).

The desk study resulted in obtaining the Cooper Landing Area Soil Survey (Van Patten, USDA, Soil Conservation Service, 1984) (the survey or the soil survey), which includes the project alignment. The survey was requested by the Kenai Peninsula Borough and completed in 1984, the contents of which were intended to address issues pertaining to the suitability of land for agriculture, homesite development and “other uses.” Characteristically, soil surveys address surficial soils and conditions (typically to a depth of about 60 inches) and might be provided as supplemental information in the context of geotechnical reports.

The survey reports the project traverses over six map soil units (Salmatof Peat, Histic Cryaquents, Bernis Very Fine Sandy Loam, Homestead Very Fine Sandy Loam, Typic Cryorthods, and Nikolai Peat), as shown in Figure 3, which show the interpreted limits of the soil units relative to the project alignment and the estimated Unified Soil Classification System (USCS) designations as appear in the survey, or the USCS designations interpreted from the soil descriptions appearing in the survey in cases where USCS designations were not provided. It is understood that the map soil units appearing in the survey are indicative of soils that are encountered at the surface (near surface soils) to a depth of about 10 inches, or so, and in most cases is not typical of the soils that underlie them. The USCS designations that are shown in the figure are intended to represent the soils that are reported to lie beneath the near surface soils to a depth of about 60 inches. Note that in this memorandum the USCS designations are used as the primary designator of the soils and, aside from this discussion and as appear in the figure, the map soil unit names will no longer be used. USCS designations are provided as Attachment A.

Figure 3: Interpreted limits of map soil units along project alignment. Note that estimated USCS designations are provided as they appear in the soil survey or as interpreted based on the soil descriptions appearing in the survey. The USCS designations represent the soils beneath the near surface soils.

Salamatof Peat

(underlain by

PT)

Histic Cryaquents (underlain by ML to

OL)

Bernis Very Fine Sandy Loam (underlain by

GP-GM, GP) Homestead Very Fine Sandy Loam (underlain by GM, GP-GM to GP to

GP-GM)

Typic Cryorthods (underlain by GM-

SM)

Nikolai

Peat (underlain by GM-

SM)

Begin Project

End Project

End paved section, begin graveled section

End separated bike path, begin shoulder widening

According to the survey, the separated bike path begins in the PT soil unit (identified as peat in the survey), but is predominantly located in the ML to OL (identified as mottled clay loam) and the GP-GM, GP (very cobbly sand) mapped soils.

The graveled section is interpreted to begin in the GP-GM, GP soils (very cobbly sand) before crossing into the GM, GP, GP-GM soils (gravelly sandy loam to gravelly loamy sand), then possibly into GM-SM (gravelly, sandy loam) at the end of the project.

Because of the depth limitations of the soil survey it is not clear to what degree, if at all, the information provided in it applies to the disturbed areas of the project. However, it may be that the lower limits of the surveyed soil units (36” to 60”), particularly the very gravelly, or gravelly sandy loam (GP to GP-GM soils), may be representative of the soils observed in the disturbed areas (i.e., exposed roadway cuts). Although not observed during the site visit, the peat (PT) at the beginning of the separated bike path should be taken into consideration in the proposed design.

Climate

The climate of the project area is reported to be influenced by maritime and continental climatic factors and exhibits some characteristics of both zones with long, moderately cold winters and short, cool summers. Noncultivated, well-drained soils generally are moist throughout the summer, but they are likely to be dry in years of exceptionally low rainfall. The other soils in the area are moist or wet in summer. (Van Patten, 1984)

Climatic data was obtained from the National Climatic Data Center (NCDC) for the two closest weather reporting stations that provided complete monthly normals for the period 1981 through 2010.

The designated reporting stations are Seward 19 N, AK US (elevation 518 feet, approx. 18 miles to the southeast) and Moose Pass 3 NW, AK US (approx. 12 miles to the east, elevation 492 feet). The weather reporting stations are shown in Figure 4.

Figure 4: Weather reporting stations shown relative to the project.

At approximate elevations of 492 feet for Moose Pass 3 NW and 518 feet for Seward 19 N the elevations of the reporting stations are within the elevation range of the project—approximately 425 feet near the Sterling Highway and 525 feet near the end of the project. The averaged data between the Seward 19 N and Moose Pass 3 NW reporting stations are presented in the table below. (The reported data for all three reporting stations are contained in Attachment B.) Table 1 shows an averaged summary of the temperature and precipitation and snow monthly normals for the 30 year monitoring period between 1981 to 2010. It should be noted that the averaged data appearing in the table is for the most recent climate normal and is not a summary of all possible observations at the two reporting stations.

9.7 mi

Table 1: Temperature, Precipitation & Snow Data

Averaged Summary of Monthly Normals1.)

1981 - 2010

Month Temperature (degrees) Precipitation Mean (inches)

Snow Mean

(inches) Daily Max. Daily Min. Mean

January 26 14 20 3.3 16.6 February 29 15 22 2.9 13.1

March 36 18 27 1.8 11.7 April 44 27 36 1.7 4.0 May 55 34 42 1.4 0.1 June 62 42 52 1.4 0.0 July 65 47 56 2.1 0.0

August 64 45 55 3.5 0.0 September 55 39 47 5.5 0.0

October 42 29 35 5.3 2.7 November 31 20 26 4.0 12.8 December 29 17 23 4.2 23.7

Annual Means = 37.0 84.5 1.) Averaged reported observations the between Seward 19 N, AK US & Moose Pass 3 NW, AK US NCDC reporting stations

Average precipitation is about 37 inches a year with average snowfall at about 84.5 inches. Based on the averaged normal appearing in the table it is inferred that in a typical year snow would cover the ground from October through late April and possibly into May.

Slope, Subgrade, and Twin 60” Culvert Conditions & Observations

Cutslopes immediately adjacent to roadway are not typically encountered within the paved section of the project, except near the end of that section. Cuts become more common through the graveled section, where the cutslopes in some areas are over-steepened with little vegetation, especially near the middle and end of the graveled section as shown in photos 5 and 6.

Photo 5: Over-steepened cutslope within the graveled section at approx. station 171+50. Possible GP or GP-GM soils.

Photo 6: Over-steepened cutslope within the graveled section at about 187+50. Possible GP or GP-GM soils.

Sloughed material collects in ditch channel

Sloughed material collects in ditch channel

Rilling

Possible seepage Possible seepage

Shallow sloughing and raveling slopes that deposit material into the ditches are present in the graveled section as shown in Photos 5, 6, 7 and 8. Seepage or signs of seepage were observed in the graveled section as can be seen in photo 6. It is interpreted that this section lies within the Homestead very fine sandy loam map unit appearing in Table 2. The unit is estimated to be somewhat excessively drained and to experience problems with cutbanks stability, as reported in the soil survey.

Photo 7: Over-steepened cutslope within the graveled section at approx. station 181+50. Note rilling on cutslope. Possible GP or GP-GM soils.

Sloughed material collects in ditch channel

Photo 8: Over-steepened cutslope within the graveled section at about station 183+50.

Note rilling on cutslope. Possible GP or GP-GM soils

Photo 9: Steep cutslope within the graveled section (station unknown). The shallow slough was likely caused by surface saturation, possibly due to seepage. (October 2012)

Sloughed material collects in ditch channel

Shallow slough

The slopes through the graveled section are characterized as moderately to heavily vegetated with bare slopes in most of the over-steepened areas (see photos). The existing cut slopes along the graveled section range from no cuts to cuts as steep as approximately 55 degrees (1.4V:1H) at station 324+25.

Existing slope angles through the paved section vary from zero to about 40 degrees (1V:1.2H) at station 211+00.

Photo 10: Snug Harbor Road at about 104+40 looking back (west).

Post Office

Snug Harbor Road

Photo 11: Paved section. View is thought to be ahead (east) at about station 124+80.

Photo 12: Graveled section at about station 180+80. View is to the west.

Slight slump at culvert location

During the site visit in October 2012 the existing ditches (despite the sub-freezing temperatures) were observed to carry a significant volume of water as can be seen in Photo 13; however sloughed material from the slopes accumulating in the ditch channel tends to obstruct the flow as can be seen in Photos 9 and 14.

Photo 13: Water (mostly frozen) in ditch along graveled section. (October 2012)

Photo 14: Sloughed material in ditch channel obstructing flow in graveled section near end of project.

The paved portion of the project appeared to be in relatively good condition during the site reconnaissance, indicating that the pavement design and construction that occurred in 2000/2001 was suitable for the conditions as can be seen in Photo 11. Subgrade conditions were reported to be problematic near the beginning of the graveled section where seeps and frost heaves were reported between approximate stations 304+00 to 306+00.

The twin 60 inch culverts are located at station 202+15 (about MP 3.81), and appeared to be in good condition during the site reconnaissance as can be seen in Photo 15. The culvert tops are exposed and should permit construction of cast-in-place headwalls that will enable roadway widening at that location. It is interpreted that the twin culverts are located within the map unit described as Bernice very fine sandy loam (ML), with very cobbly sand between depths of 8 inches to 60 inches (USCS;

GP-GM to GP). This map unit is estimated to have low potential for frost action and rapid permeability (6 – 20 in/hr) below 8”, as reported in the soil survey.

Photo 15: Twin culverts at station 202+15. (October 2012)

During the site visits the only observed slope instability appeared to be surficial in nature due to over-steepened cuts with little to no vegetation and seepage. The maintenance staff confirmed our interpretation that the slope raveling occurs primarily under freeze/thaw conditions and during periods of heavy rain.

RECOMMENDATIONS

Raveling Slopes

The recommended mitigation for the raveling cuts is slope flattening. The recommended slope angle is 1:1.75 (V:H), or flatter. It is understood that flattening the slopes will encroach beyond right-of-way through some sections. Slopes could be steepened up to 1:1 by constructing riprap rock inlays as discussed later in this section under Rock Inlaid Slopes.

Pinned draped mesh with erosion control mat behind the mesh was also considered for some of the steeper cutslopes but was also removed from further consideration based on cost and aesthetic concerns.

Retaining structures

Retaining structures such as walls and rockeries were considered but removed from further consideration owing to the cost, heights required, and design and/or construction concerns. Also, retaining structures would not mitigate the raveling slopes, and material originating from the slope above the rockeries or walls might launch off the top of the structures and land in the bike path and/or the road.

Culvert Headwalls

Since frost heaving was reported in places on the project, it is recommended that the footings for the headwalls for the twin 60 inch culverts extend below ground a minimum of 42 inches underlain with

1.5 feet of non-frost-susceptible bedding containing 5% or less passing the 200 mesh sieve. Based on the interpreted conditions at the culvert location the bearing capacity for the headwalls is sufficient to support the cast-in-place headwalls with the recommended embedment.

Earthwork Materials

Based on visual observations of the existing cutslopes and assessment of the bagged grab samples, the material excavated from the cutslopes is interpreted to be suitable for construction of embankments and subgrade. Since observation of the soils beneath the road surface was not possible, it is recommended that any material excavated from beneath the road should be wasted.

Subex/Frost Heave Mitigation

The recommended mitigation for the reported frost heaving occurring between 304+00 and 306+00 is removal of the unsuitable frost-susceptible soils. Subexcavation should extend to minimum depth of 3 feet beneath the base layer and be backfilled with non-frost-susceptible material having less than 5% or less passing the 200 mesh sieve. A layer of biaxial geogrid should be placed at the bottom of the excavation. The entire excavation should be lined with a Class I Type C earthwork geotextile. The subex design should include a means to drain the subexcavated zone.

Rock Inlay Slopes

Rock inlays are recommended to mitigate raveling slopes steeper than 1:1.75 (V:H). Rock inlays of a minimum of 2 foot thick and constructed out of Class 1 riprap rock are recommended that are no steeper than 1:1. For the higher slopes, constructability would likely limit the height of the slope for which rock inlay construction is practical.

Separated Bike Path

Present design calls for a separated bike path to be constructed between Stations 100+00 and 143+43.

Based on the information appearing in this memorandum the bike path is interpreted to begin in PT soils for the first 300 to 400 feet, transitioning into ML to OL soils, and then transitioning into GM, GP to GM-GP soils. Given the unknown subsurface conditions of this project it is recommended that the separated bike path be constructed with a minimum 12 inch layer of select borrow underlain by a Class I Type C earthwork geotextile to provide subgrade support.

Fill Slopes

Should acceptable onsite excavated materials be used for embankment construction, construct at a ratio of 1:1.5 (V:H), or flatter. Excavated materials containing organic material should not be used for embankment construction.

~~ End Memorandum ~~

CC: Jack Doucey, Designer Malcolm Ulrich, Geotechnical Team Lead Jim Neighorn, Hydraulics Engineer Geotechnical File

(Intentionally blank)

Attachment A

Unified Soil Classification System (USCS)

(In te nt io na lly b la nk

Attachment B

Climate Reports

Quick Data View | Climate Data Online (CDO) | National Climatic Data Center (NCDC) http://www.ncdc.noaa.gov/cdo-web/quickdata[8/2/2013 6:45:18 AM]

08/02/2013

U.S. Department of Commerce Summary of

Monthly Normals 1981-2010

National Climatic Data Center National Oceanic & Atmospheric Administration Federal Building National Environmental Satellite, Data, and Information Service

151 Patton Avenue

Asheville, North Carolina 28801 www.ncdc.noaa.gov

Station: MOOSE PASS 3 NW, AK US GHCND:USC00505894

Elev: 492 ft. Lat: 60.503° N Lon: 149.426° W Temperature (°F)

Mean Cooling Degree Days Heating Degree Days Mean Number of Days Base (above) Base (below)

Month Daily Max

Daily Min

Mean Long Term Max Std.

Dev.

Long Term Min Std.

Dev.

Long Term Avg Std.

Dev.

55 57 60 65 70 72 55 57 60 65 Max

Max

Max

Max

Min

Min

1 26.4 11.6 19.0 7.4 9.9 8.6 0 0 0 0 0 0 1116 1178 1271 1426 0.0 0.0 0.0 15.9 27.9 8.5 2 29.4 13.0 21.2 6.3 8.7 7.4 0 0 0 0 0 0 946 1002 1086 1226 0.0 0.0 0.0 12.1 24.7 6.5 3 37.0 16.7 26.9 3.3 7.0 5.0 0 0 0 0 0 0 873 935 1028 1183 0.0 0.0 0.1 5.6 28.0 4.5 4 45.5 27.0 36.3 3.2 3.7 3.1 0 0 0 0 0 0 563 623 713 863 0.0 0.0 6.7 0.8 21.2 0.5 5 56.3 34.4 45.3 2.9 2.1 1.8 1 1 -7777 0 0 0 300 362 454 609 0.0 0.0 24.0 0.0 10.7 0.0 6 63.9 41.9 52.9 3.9 1.5 2.3 33 17 6 -7777 -7777 0 96 140 219 363 0.0 0.0 29.4 0.0 1.5 0.0 7 67.0 47.3 57.2 3.9 2.1 2.4 89 52 19 2 -7777 0 22 47 107 245 0.0 0.0 31.0 0.0 0.0 0.0 8 66.1 45.4 55.7 3.0 1.8 1.8 64 37 14 1 0 0 41 76 146 288 0.0 0.0 31.0 0.0 0.5 0.0 9 55.9 38.1 47.0 2.0 2.9 2.0 2 -7777 -7777 0 0 0 242 300 390 540 0.0 0.0 26.2 0.0 6.1 0.0

10 42.3 27.8 35.0 2.9 5.1 3.8 -7777 0 0 0 0 0 618 680 773 928 0.0 0.0 3.2 2.8 19.8 0.4 11 30.9 17.5 24.2 5.9 7.6 6.7 0 0 0 0 0 0 924 984 1074 1224 0.0 0.0 0.1 13.3 26.0 3.6 12 28.8 13.2 21.0 5.8 7.7 6.7 0 0 0 0 0 0 1054 1116 1209 1364 0.0 0.0 0.1 15.4 27.7 6.9

Summary 45.8 27.8 36.8 4.2 5.0 4.3 189 107 39 3 0 0 6795 7443 8470 10259 0.0 0.0 151.8 65.9 194.1 30.9

@ Denotes mean number of days greater than 0 but less than 0.05; or insufficient data for calculation.

-4444: year-round risk of frost-freeze -6666: parameter undefined; insufficient occurrences to compute value -7777: a non-zero value that would round to zero 9999, Empty, or blank, cells indicate an average greater than 0 but less than 0.05.

Precipitation (in.)

Totals Mean Number of Days Precipitation Probabilities

Probability that precipitation will be equal to or less than the indicated amount

Means Daily Precipitation Monthly Precipitation

vs. Probability Levels

Month Mean >= 0.01 >= 0.10 >= 0.50 >= 1.00 .25 .50 .75 1 2.43 10.6 6.4 1.5 0.1 0.98 2.18 3.66 2 2.73 8.6 4.7 1.4 0.4 1.92 2.66 3.10 3 1.31 8.2 3.8 1.2 0.3 0.53 1.07 2.06 4 1.10 7.2 3.0 0.3 0.0 0.67 1.06 1.42 5 1.05 6.8 3.2 0.6 0.0 0.40 0.87 1.52 6 0.86 6.0 3.1 0.2 0.0 0.54 0.74 1.03 7 1.43 7.4 4.2 0.8 0.1 0.66 1.30 2.04 8 3.09 10.6 6.9 2.0 0.4 1.73 3.44 3.97 9 4.51 11.6 8.4 3.0 1.2 1.99 4.18 5.73

10 4.26 11.4 8.2 2.5 0.8 3.51 3.93 4.91 11 3.50 10.0 6.5 2.1 0.7 1.35 2.92 5.62 12 3.11 11.4 7.3 2.3 0.7 1.42 2.95 3.77

Summary 29.38 109.8 65.7 17.9 4.7 15.70 27.30 38.83

@ Denotes mean number of days greater than 0 but less than 0.05; or insufficient data for calculation.

-4444: year-round risk of frost-freeze -6666: parameter undefined; insufficient occurrences to compute value -7777: a non-zero value that would round to zero 9999, Empty, or blank, cells indicate an average greater than 0 but less than 0.05.

http://www.ncdc.noaa.gov/cdo-web/quickdata[8/2/2013 6:45:18 AM]

Snow (in.)

Totals Mean Number of Days Snow Probabilities

Probability that snow will be equal to or less than the indicated amount Means Snowfall >= Thresholds Snow Depth >= Thresholds Monthly Snow vs. Probability

Levels Values derived from the incomplete gamma distribution.

Month Snowfall

Mean

0.1 1.0 3.0 5.0 10.0 1 3 5 10 .25 .50 .75

1 13.9 6.8 5.0 2.2 0.8 0.2 28.7 25.1 21.9 16.2 10.9 15.0 18.9 2 10.7 4.7 3.4 1.4 0.5 0.0 26.5 22.1 19.5 16.0 5.0 8.5 16.5 3 12.2 4.0 3.0 1.3 0.7 0.2 24.9 20.5 15.8 13.0 0.9 6.2 18.5 4 3.2 1.6 1.2 0.4 0.1 0.0 10.1 8.3 7.0 4.8 0.0 1.2 5.0 5 0.0 0.0 0.0 0.0 0.0 0.0 0.5 0.2 -7777 0.0 0.0 0.0 0.0 6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 9 -7777 -7777 -7777 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

10 3.5 1.6 1.2 0.4 0.2 0.0 4.1 2.2 1.4 0.2 0.0 1.5 6.0 11 13.6 4.8 3.6 1.7 0.9 0.1 16.9 11.5 7.7 2.2 5.8 13.5 17.1 12 20.7 7.1 5.7 3.0 1.2 0.3 25.9 23.9 21.4 16.9 13.5 17.5 29.0

Summary 77.8 30.6 23.1 10.4 4.4 0.8 137.6 113.8 94.7 69.3 36.1 63.4 111.0

@ Denotes mean number of days greater than 0 but less than 0.05; or insufficient data for calculation.

-4444: year-round risk of frost-freeze -6666: parameter undefined; insufficient occurrences to compute value -7777: a non-zero value that would round to zero 9999, Empty, or blank, cells indicate an average greater than 0 but less than 0.05.

Growing Degree Units (Monthly) Base Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

40 -7777 1 1 19 173 387 532 488 220 30 3 2 45 0 0 0 2 62 239 377 333 100 6 -7777 -7777 50 0 0 0 -7777 14 110 223 183 25 1 0 0 55 0 0 0 0 1 33 89 64 2 -7777 0 0 60 0 0 0 0 -7777 6 19 14 -7777 0 0 0

Growing Degree Units for Corn (Monthly) 50/86 -7777 0 -7777 15 109 210 274 258 95 4 -7777 -7777

Growing Degree Units (Accumulated Monthly) Base Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

40 -7777 1 2 21 194 581 1113 1601 1821 1851 1854 1856 45 0 0 0 2 64 303 680 1013 1113 1119 -7777 -7777 50 0 0 0 -7777 14 124 347 530 555 556 556 556 55 0 0 0 0 1 34 123 187 189 -7777 189 189 60 0 0 0 0 -7777 6 25 39 -7777 39 39 39

50/86 -7777 0 -7777 15 124 334 608 866 961 965 -7777 -7777

Note: For corn, temperatures below 50 are set to 50, and temperatures above 86 are set to 86 M indicates the value is missing -4444: year-round risk of frost-freeze -6666: parameter undefined; insufficient occurrences to compute value http://www.ncdc.noaa.gov/cdo-web/quickdata[8/2/2013 6:46:51 AM]

08/02/2013

U.S. Department of Commerce Summary of

Monthly Normals 1981-2010

National Climatic Data Center National Oceanic & Atmospheric Administration Federal Building National Environmental Satellite, Data, and Information Service

151 Patton Avenue

Asheville, North Carolina 28801 www.ncdc.noaa.gov

Station: SEWARD 19 N, AK US GHCND:USC00508377

Elev: 518 ft. Lat: 60.354° N Lon: 149.348° W Temperature (°F)

Mean Cooling Degree Days Heating Degree Days Mean Number of Days Base (above) Base (below)

Month Daily Max

Daily Min

Mean Long Term Max Std.

Dev.

Long Term Min Std.

Dev.

Long Term Avg Std.

Dev.

55 57 60 65 70 72 55 57 60 65 Max

Max

Max

Max

Min

Min

1 26.3 16.3 21.3 5.8 7.4 6.5 0 0 0 0 0 0 1045 1107 1200 1355 0.0 0.0 0.0 19.2 28.0 4.2 2 28.8 17.1 23.0 5.0 6.6 5.7 0 0 0 0 0 0 897 953 1037 1177 0.0 0.0 -7777 14.5 26.1 3.3 3 35.2 19.5 27.4 3.8 5.4 4.4 0 0 0 0 0 0 857 919 1012 1167 0.0 0.0 0.0 7.5 28.7 1.0 4 42.8 26.9 34.9 2.9 3.3 2.9 0 0 0 0 0 0 604 664 754 904 0.0 0.0 2.9 0.6 25.0 -7777 5 53.2 34.1 43.6 3.0 1.5 1.9 -7777 -7777 0 0 0 0 352 414 507 662 0.0 0.0 19.2 0.0 10.2 0.0 6 60.2 41.5 50.9 2.9 1.3 1.8 18 9 3 -7777 0 0 143 194 277 425 0.0 0.0 28.0 0.0 0.2 0.0 7 62.6 46.8 54.7 2.5 1.2 1.7 44 23 7 -7777 0 0 54 95 171 320 0.0 0.0 30.9 0.0 0.0 0.0 8 61.6 45.4 53.5 2.8 1.6 1.9 31 16 4 -7777 0 0 78 125 206 357 0.0 0.0 30.8 0.0 0.0 0.0 9 53.2 39.0 46.1 2.0 2.3 1.7 1 -7777 -7777 0 0 0 268 327 417 567 0.0 0.0 21.8 0.0 2.8 0.0

10 40.8 30.5 35.7 2.7 3.1 2.9 -7777 0 0 0 0 0 600 662 755 910 0.0 0.0 1.2 2.1 19.2 0.0 11 31.0 22.8 26.9 4.0 4.5 4.2 0 0 0 0 0 0 843 903 993 1143 0.0 0.0 -7777 14.5 26.0 0.1 12 28.5 19.9 24.2 3.9 4.6 4.2 0 0 0 0 0 0 955 1017 1110 1265 0.0 0.0 -7777 18.8 27.8 0.5

Summary 43.7 30.0 36.9 3.4 3.6 3.3 94 48 14 0 0 0 6696 7380 8439 10252 0.0 0.0 134.8 77.2 194.0 9.1

@ Denotes mean number of days greater than 0 but less than 0.05; or insufficient data for calculation.

-4444: year-round risk of frost-freeze -6666: parameter undefined; insufficient occurrences to compute value -7777: a non-zero value that would round to zero 9999, Empty, or blank, cells indicate an average greater than 0 but less than 0.05.

Precipitation (in.)

Totals Mean Number of Days Precipitation Probabilities

Probability that precipitation will be equal to or less than the indicated amount

Means Daily Precipitation Monthly Precipitation

vs. Probability Levels

Month Mean >= 0.01 >= 0.10 >= 0.50 >= 1.00 .25 .50 .75 1 4.18 13.6 8.2 2.1 0.8 1.81 2.55 6.31 2 3.06 12.6 7.0 1.8 0.5 2.00 2.86 3.81 3 2.24 11.1 6.1 1.1 0.2 0.64 1.77 3.28 4 2.24 12.3 6.1 1.0 0.2 1.37 1.77 2.72 5 1.75 13.5 5.4 0.5 0.1 0.96 1.40 2.12 6 1.87 14.3 6.1 0.8 -7777 1.20 1.54 2.12 7 2.77 16.5 8.1 1.0 -7777 1.62 2.23 3.50 8 3.99 17.0 9.6 2.2 0.4 2.51 3.28 5.49 9 6.45 19.8 13.2 4.3 1.4 4.08 6.22 9.04

10 6.33 18.4 11.1 3.8 1.4 3.62 5.44 7.67 11 4.53 13.9 8.7 2.4 1.1 1.87 3.02 5.84 12 5.30 16.5 10.3 3.1 1.1 3.20 5.52 6.86

Summary 44.71 179.5 99.9 24.1 7.2 24.88 37.60 58.76

@ Denotes mean number of days greater than 0 but less than 0.05; or insufficient data for calculation.

-4444: year-round risk of frost-freeze -6666: parameter undefined; insufficient occurrences to compute value http://www.ncdc.noaa.gov/cdo-web/quickdata[8/2/2013 6:46:51 AM]

Snow (in.)

Totals Mean Number of Days Snow Probabilities

Probability that snow will be equal to or less than the indicated amount

Means Snowfall >= Thresholds Snow Depth >= Thresholds Monthly Snow vs. Probability Levels

Values derived from the incomplete gamma distribution.

Month Snowfall Mean

0.1 1.0 3.0 5.0 10.0 1 3 5 10 .25 .50 .75

1 19.3 9.9 5.9 2.2 1.0 0.1 31.0 31.0 30.3 28.2 7.8 19.8 23.3 2 15.4 8.7 4.7 1.7 0.6 0.2 28.2 28.2 27.9 27.1 7.7 12.8 15.8 3 11.2 7.1 4.0 1.2 0.4 0.1 31.0 31.0 30.7 30.4 4.3 11.2 17.6 4 4.7 3.5 1.7 0.4 0.1 -7777 29.0 28.7 28.3 26.8 1.0 2.5 5.8 5 0.2 0.3 -7777 0.0 0.0 0.0 10.6 9.3 8.3 6.3 0.0 0.0 0.0 6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

10 1.9 2.0 0.8 0.2 0.1 0.0 3.7 2.0 1.0 0.2 0.0 1.0 3.0 11 11.9 7.7 4.4 1.6 0.6 0.0 20.9 17.5 13.3 4.9 5.8 11.6 15.8 12 26.6 12.0 7.9 3.1 1.4 0.2 29.3 28.9 27.0 21.6 12.7 18.4 37.7

Summary 91.2 51.2 29.4 10.4 4.2 0.6 183.7 176.6 166.8 145.5 39.3 77.3 119.0

@ Denotes mean number of days greater than 0 but less than 0.05; or insufficient data for calculation.

-4444: year-round risk of frost-freeze -6666: parameter undefined; insufficient occurrences to compute value -7777: a non-zero value that would round to zero 9999, Empty, or blank, cells indicate an average greater than 0 but less than 0.05.

Growing Degree Units (Monthly) Base Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

40 -7777 -7777 -7777 7 126 325 456 418 189 19 1 1 45 0 0 0 1 39 180 301 264 75 4 -7777 0 50 0 0 0 -7777 8 70 150 117 14 1 0 0 55 0 0 0 0 -7777 18 44 31 1 -7777 0 0 60 0 0 0 0 0 3 7 4 -7777 0 0 0

50/86 -7777 -7777 -7777 6 73 155 199 182 62 2 -7777 -7777

Growing Degree Units (Accumulated Monthly) Base Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

40 -7777 -7777 -7777 7 133 458 914 1332 1521 1540 1541 1542 45 0 0 0 1 40 220 521 785 860 864 -7777 864 50 0 0 0 -7777 8 78 228 345 359 360 360 360 55 0 0 0 0 -7777 18 62 93 94 -7777 94 94 60 0 0 0 0 0 3 10 14 -7777 14 14 14

50/86 -7777 -7777 -7777 6 79 234 433 615 677 679 -7777 -7777

Note: For corn, temperatures below 50 are set to 50, and temperatures above 86 are set to 86 M indicates the value is missing -4444: year-round risk of frost-freeze -6666: parameter undefined; insufficient occurrences to compute value