9 - Palmer Storm Report part 2.pdf

Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit.

Custom Soil Resource Report Soil Map

388110 388170 388230 388290 388350 388410 388470

388110 388170 388230 388290 388350 388410 388470

61° 36' 13'' N

9°

' 3 3'

' W 61° 36' 13'' N

9°

' 6

'' W

61° 35' 56'' N

9°

' 3

3' ' W

61° 35' 56'' N

9°

' 6

'' W

N

Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 6N WGS84 0 100 200 400 600

Feet 0 35 70 140 210

Meters Map Scale: 1:2,640 if printed on A portrait (8.5" x 11") sheet.

Soil Map may not be valid at this scale.

MAP LEGEND MAP INFORMATION

Area of Interest (AOI) Area of Interest (AOI)

Soils Soil Map Unit Polygons

Soil Map Unit Lines

Soil Map Unit Points

Special Point Features Blowout

Borrow Pit

Clay Spot

Closed Depression

Gravel Pit

Gravelly Spot

Landfill

Lava Flow

Marsh or swamp

Mine or Quarry

Miscellaneous Water

Perennial Water

Rock Outcrop

Saline Spot

Sandy Spot

Severely Eroded Spot

Sinkhole

Slide or Slip

Sodic Spot

Spoil Area

Stony Spot

Very Stony Spot

Wet Spot

Other

Special Line Features

Water Features Streams and Canals

Transportation Rails

Interstate Highways

US Routes

Major Roads

Local Roads

Background Aerial Photography

The soil surveys that comprise your AOI were mapped at 1:24,000.

Warning: Soil Map may not be valid at this scale.

Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale.

Please rely on the bar scale on each map sheet for map measurements.

Source of Map: Natural Resources Conservation Service Web Soil Survey URL:

Coordinate System: Web Mercator (EPSG:3857)

Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required.

This product is generated from the USDA-NRCS certified data as of the version date(s) listed below.

Soil Survey Area: Matanuska-Susitna Valley Area, Alaska Survey Area Data: Version 25, Sep 2, 2025

Soil map units are labeled (as space allows) for map scales 1:50,000 or larger.

Date(s) aerial images were photographed: Mar 25, 2015—Oct 19, 2023

The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident.

Map Unit Legend

Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI

105 Bodenburg silt loam, 0 to 3 percent slopes

35.7 100.0%

Totals for Area of Interest 35.7 100.0%

Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit.

A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class.

Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils.

Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape.

The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas.

An identifying symbol precedes the map unit name in the map unit descriptions.

Each description includes general facts about the unit and gives important soil properties and qualities.

Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement.

Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series.

Some map units are made up of two or more major soils or miscellaneous areas.

These map units are complexes, associations, or undifferentiated groups.

A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps.

The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example.

An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example.

An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example.

Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example.

Matanuska-Susitna Valley Area, Alaska

105—Bodenburg silt loam, 0 to 3 percent slopes

Map Unit Setting National map unit symbol: 1p8f Elevation: 100 to 400 feet Mean annual precipitation: 15 to 20 inches Mean annual air temperature: 34 to 36 degrees F Frost-free period: 90 to 110 days Farmland classification: Farmland of local importance

Map Unit Composition Bodenburg and similar soils: 90 percent Minor components: 10 percent Estimates are based on observations, descriptions, and transects of the mapunit.

Description of Bodenburg

Setting Landform: Plains Down-slope shape: Linear Across-slope shape: Linear Parent material: Silty loess over sandy and gravelly glaciofluvial deposits

Typical profile Oe - 0 to 2 inches: moderately decomposed plant material A1 - 2 to 5 inches: silt loam A2,Bw - 5 to 50 inches: silt loam 2BC,2C - 50 to 60 inches: very gravelly loamy coarse sand

Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: 41 to 59 inches to strongly contrasting textural stratification Drainage class: Well drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat): Moderately high (0.57 to 1.42 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water supply, 0 to 60 inches: Very high (about 15.6 inches)

Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 3e Hydrologic Soil Group: B Ecological site: R224XY304AK - Skeletal Slopes Provisional Ecological Site

Group Other vegetative classification: Silty slopes (F170XB011AK), Mixed paper birch-white spruce/herbaceous forest (040b) Hydric soil rating: No

Minor Components

Steeper soils Percent of map unit: 5 percent Landform: Plains Down-slope shape: Linear Across-slope shape: Linear Hydric soil rating: No

Yensus Percent of map unit: 3 percent Landform: Outwash plains Down-slope shape: Linear Across-slope shape: Linear Ecological site: F224XY011AK - Silty slopes Other vegetative classification: Silty slopes (F170XB011AK), Mixed paper birch-white spruce/herbaceous forest (040b) Hydric soil rating: No

Temporarily ponded soils Percent of map unit: 2 percent Landform: Depressions Down-slope shape: Concave Across-slope shape: Concave Hydric soil rating: No

References American Association of State Highway and Transportation Officials (AASHTO).

2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition.

American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00.

Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31.

Federal Register. July 13, 1994. Changes in hydric soils of the United States.

Federal Register. September 18, 2002. Hydric soils of the United States.

Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils in the United States.

National Research Council. 1995. Wetlands: Characteristics and boundaries.

Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service.

U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/national/soils/?cid=nrcs142p2_054262

Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577

Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580

Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section.

United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1.

United States Department of Agriculture, Natural Resources Conservation Service.

National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ home/?cid=nrcs142p2_053374

United States Department of Agriculture, Natural Resources Conservation Service.

National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/ detail/national/landuse/rangepasture/?cid=stelprdb1043084 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_054262 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_054262 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/home/?cid=nrcs142p2_053374 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/home/?cid=nrcs142p2_053374 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/landuse/rangepasture/?cid=stelprdb1043084 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/landuse/rangepasture/?cid=stelprdb1043084

United States Department of Agriculture, Natural Resources Conservation Service.

National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/soils/scientists/?cid=nrcs142p2_054242

United States Department of Agriculture, Natural Resources Conservation Service.

2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook

296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?

cid=nrcs142p2_053624

United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. http:// www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf

Custom Soil Resource Report http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/scientists/?cid=nrcs142p2_054242 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/scientists/?cid=nrcs142p2_054242 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053624 http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053624 http://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf http://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf

Palmer Courthouse Renovation & Expansion

APPENDIX

B

SSA OUTPUT

Project Description

Palmer Infiltration Model.SPF

Project Options

CFS

Elevation

Santa Barbara UH

User-Defined

Hydrodynamic

YES

YES

Analysis Options

00:00:00 0:00:00

00:00:00 0:00:00

00:00:00 0:00:00

0 days

0 01:00:00 days hh:mm:ss

0 00:05:00 days hh:mm:ss

0 00:05:00 days hh:mm:ss

30 seconds

Number of Elements Qty

Rainfall Details

SN Rain Gage Data Data Source Rainfall Rain State County Return Rainfall Rainfall

ID Source ID Type Units Period Depth Distribution

(years) (inches)

49 Time Series 25-yr Intensity inches Alaska Matanuska-Susitna (B) 25.00 2.24 SCS Type I 24-hr

Antecedent Dry Days

File Name

Flow Units

Elevation Type

Hydrology Method

Time of Concentration (TOC) Method

Link Routing Method

Enable Overflow Ponding at Nodes

Skip Steady State Analysis Time Periods ...

Start Analysis On

End Analysis On

Start Reporting On

Storage Nodes

Runoff (Dry Weather) Time Step

Runoff (Wet Weather) Time Step

Reporting Time Step

Routing Time Step

Rain Gages

Subbasins

Nodes

Junctions

Outfalls

Flow Diversions

Inlets

Outlets

Pollutants

Land Uses

Links

Channels

Pipes

Pumps

Orifices

Weirs

Subbasin Summary

SN Subbasin Area Impervious Impervious Pervious Total Total Total Peak Time of

ID Area Area Curve Area Curve Rainfall Runoff Runoff Runoff Concentration

Number Number Volume

(ac) (%) (in) (in) (ac-in) (cfs) (days hh:mm:ss)

1 Sub-01 0.35 13.00 98.00 61.00 2.24 0.37 0.13 0.06 0 00:05:00

Node Summary

SN Element Element Invert Ground/Rim Initial Surcharge Ponded Peak Max HGL Max Min Time of Total Total Time

ID Type Elevation (Max) Water Elevation Area Inflow Elevation Surcharge Freeboard Peak Flooded Flooded

Elevation Elevation Attained Depth Attained Flooding Volume

Attained Occurrence

(ft) (ft) (ft) (ft) (ft²) (cfs) (ft) (ft) (ft) (days hh:mm) (ac-in) (min)

1 Out-02 Outfall 10.00 0.00 10.00

2 DRYWELL-01 Storage Node 226.75 251.75 0.00 0.00 0.06 235.12 0.00 0.00

Subbasin Hydrology

Subbasin : Sub-01

Input Data

Area (ac) ..................................................... 0.35

Impervious Area (%)

Impervious Area Curve Number

Pervious Area Curve Number

Rain Gage ID

Composite Curve Number

32 Area Soil Curve

Soil/Surface Description (acres) Group Number

Composite Area & Weighted CN 0.35 65.81

Subbasin Runoff Results

Total Rainfall (in) ......................................... 2.24

Total Runoff (in) .......................................... 0.37

Peak Runoff (cfs) ......................................... 0.06

Weighted Curve Number .............................. 65.81

Time of Concentration (days hh:mm:ss) ....... 0 00:05:00

Subbasin : Sub-01

Rainfall Intensity Graph

Time (hrs)

95908580757065605550454035302520151050

R a in fa ll in /h r)

1.8

1.7

1.6

1.5

1.4

1.3

1.2

1.1

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

Runoff Hydrograph

Time (hrs)

95908580757065605550454035302520151050

R u n o ff c fs

0.062

0.06

0.058

0.056

0.054

0.052

0.05

0.048

0.046

0.044

0.042

0.04

0.038

0.036

0.034

0.032

0.03

0.028

0.026

0.024

0.022

0.02

0.018

0.016

0.014

0.012

0.01

0.008

0.006

0.004

0.002

Storage Nodes

Storage Node : DRYWELL-01

Input Data

226.75

251.75

25.00

0.00

-226.75

0.00

0.00

Infiltration/Exfiltration

0.0045

Output Summary Results

0.06

0.06

0.27

235.12

8.37

228.26

1.51

0 21:52

0.473

Peak Exfiltration Flow Rate (cfm)

Invert Elevation (ft)

Max (Rim) Elevation (ft)

Max (Rim) Offset (ft)

Initial Water Elevation (ft)

Initial Water Depth (ft)

Ponded Area (ft²)

Evaporation Loss

Constant Flow Rate (cfs)

Peak Inflow (cfs)

Peak Lateral Inflow (cfs)

Peak Outflow (cfs)

Total Flooded Volume (ac-in)

Total Time Flooded (min)

Total Retention Time (sec)

Max HGL Elevation Attained (ft)

Max HGL Depth Attained (ft)

Average HGL Elevation Attained (ft)

Average HGL Depth Attained (ft)

Time of Max HGL Occurrence (days hh:mm)

Total Exfiltration Volume (1000-ft³)

Palmer Courthouse Renovation & Expansion

APPENDIX

C

OPERATIONS & MAINTENANCE

Drywells Page 1 of 2

INSPECTION CRITERIA:

1. The depth of sediment accumulation is noted in the field notes. If sediment build-up appears to prevent proper infiltration the drywell is cleaned.

3. The structure is checked for structural integrity and/or damage for the following items:

A. Drywell is clear and free from plugging.

B. Cracks and deterioration of the structure or grouting including rotting of concrete structure, exposure of rebar or structural matting, discontinuous sections in the grout.

C. Structural integrity is in good alignment, showing no evidence of cracking, lifting, or movement.

D. Signs of abrasion and/or corrosion.

MAINTENANCE CRITERIA:

1. Remove sediment using vactor truck.

2. If repairs and/or maintenance are required, record the condition and transfer to the DOT&PF work log for prioritization and scheduling.

A. Record and/or photograph plugging condition for DOT&PF work log.

B. Record and/or photograph cracks and deterioration for DOT&PF work log.

C. Record and/or photograph structural integrity for DOT&PF work log.

D. Record and/or photograph corrosion or abrasion for DOT&PF work log.

INSPECTION SCHEDULE:

Drywell inspection is performed on an annual basis.

MAINTENANCE SCHEDULE:

Drywell maintenance is performed as identified through inspections.

RESOURCE NEEDS

DEFINITIONS:

Drywells are facilities that collect and infiltrate storm water runoff into the ground.

PERMIT REFERENCES:

This SOP was prepared according to the permit requirements (3.4.3.1).

ACTIVITY DESCRIPTION:

An inspection is completed of each drywell and minor cleaning, such as litter pick-up, is completed as part of the inspection routine. The inspection and maintenance of outfalls requires accurate record keeping. This task is completed by using MOA’s GIS mapping system to inventory the drainage structures. The DOT&PF Supervisor prints out grid maps identifying the drywells and assigns maintenance crews to inspect the structures on the map. Crews inspect and prepare the equipment fleet needed to perform the inspection of the assigned structures. Each drywell is visually inspected for sediment buildup, structural deterioration, and evidence of infiltration.

Drywells Page 2 of 2

POLLUTION PREVENTION/GOOD HOUSEKEEPING PROCEDURES

Train field crews annually and provide frequent verbal reminders on how to operate the equipment and what to look for during routine inspections prior to the field season.

Keep training records that include attendees, date, and description of training.

Check all vehicles, including vactor trucks, used for stormwater infrastructure inspection and maintenance for operational condition, leaks, and deficiencies prior to leaving the DOT&PF yard. For equipment inspection and maintenance:

• Place drip pans under equipment parts that may leak. Empty drip pans when they are more than ½ full.

• Clean up all drips and leaks immediately.

• Empty fuel and oil filters where drips cannot reach stormwater.

• Do not wash equipment or pavement surrounding equipment where wash water can enter storm drains.

Check fittings associated with the vactor truck prior to starting operation of the vactor truck to remove accumulated sediment material.

Remove all litter and debris found during the inspection procedure. Dispose of litter/debris from the site in solid waste containers located at the DOT&PF yard.

Sediment and debris collected in the vactor truck are transferred to the snow disposal site and used to regrade the site or a paid disposal of material is made through Anchorage Sand and Gravel Company. If sediment is spilled or released during collection or disposal clean the area thoroughly and immediately.