Hwy 46 Soils and Geology Report Page 1

COVER INFORMATION

Reply To: 2550 Soil Management 

 2520 Watershed Protection and Management

Subject: SOIL AND GEOLOGY REPORT

 Hwy 46 Project 

To: District Ranger, Detroit Ranger District

By: Douglas C. Shank, Forest Geologist Date: December 3, 2015

I. INTRODUCTION

A. PURPOSE AND NEED FOR PROJECT

The Detroit Ranger District of the Willamette National Forest proposes to manage several hundred acres 

of plantations and natural, fire regenerated stands through a variety of means within the Breitenbush 

River Watershed. Potential units are located throughout the Upper Breitenbush which includes the North 

Fork Breitenbush, South Fork Breitenbush, Devils Creek and Humbug Creek drainages, as well as 

several other smaller drainages. Projects could include vegetation management for watershed restoration, 

fuels treatments for defensible space, the maintenance or enhancement of visual quality objectives, the 

reintroduction of scaled disturbance to meet serial stage objectives, or the manipulation of stand densities 

to promote long term stand health. 

The purpose of the project is to: 

1) Improve the growth of various natural or plantation timber stands and promote forest health by 

reducing current stocking levels to enhance growth and vigor of the remaining trees and to reduce future 

losses from fire, insects, disease, and from snow down or breakage; 2) Create variability in stand densities 

to provide habitats for various plant and animal species or communities; 3) Manage activity-created and 

natural fuels as needed to meet Forest Plan Standards and the historical fire regime processes by under 

burning, machine or hand piling and burning, or spot burning; 4) Maintain, store, reduce or reconfigure 

the existing road system as much as is practical to provide both short and long term access; and 5) 

Provide a sustainable supply of commercial wood products. 

B. PROPOSED ACTION AND CONNECTED ACTIONS

The District Ranger for the Detroit Ranger District of the Willamette National Forest proposes to 

implement the following actions during the next five to ten years within younger forests in various land 

management allocations. Possible units are found in various sections in Townships 9 and 10 South, in 

Ranges from 6 East to 7 East. 

Manage several hundred acres of natural or management created stands through various means in 

order to meet a variety of silvicultural or other resource objectives. Some actions would include 

the harvest of commercial products such as saw logs.

Lessen the fire hazard through fuels reduction. Slash would be treated as necessary where it was 

created as a result of management activities associated with the project, especially in areas where 
Hwy 46 Soils and Geology Report Page 2

there is a high risk of fire starts. Other areas could have under burning without the associated 

stand treatments. 

Construct temporary or permanent roads to access harvest units as necessary and, after 

implementation, decommission the temporary roads by scarification or subsoiling, seeding, and 

re-establishing natural drainage patterns, as needed. 

Reconstruct existing Forest transportation system roads as needed to access harvest units; 

construct, reconstruct, or modify landings for helicopters, skylines, and ground based yarding 

systems; and implement other actions as needed, such as project mitigations, reforestation, or 

road closures.

Develop or expand rock resources as necessary for a variety of rock products to be used for the 

management of the Forest transportation system. Expansion would generally be limited in extent, likely 

less than one acre, and confined to areas of brush or plantation trees, unless done in conjunction with a 

proposed harvest unit. 

II. SUMMARY

A. RESOURCES CONSIDERED

This report documents the existing conditions and potential impacts to the soil and geology resource. The 

major short-term impacts to soil productivity from management and harvest activity, as discussed in the 

Willamette National Forest Final Environmental Impact Statement (FEIS 1990), include displacement, 

compaction, nutrient loss, and instability. In most situations, preventing soil impacts is the most effective 

and feasible way of ensuring long-term soil productivity.

B. METHODS

The information for this report was obtained by intensive field reconnaissance of proposed units as well 

as the terrain surrounding the units, when applicable. In several units, where ground based harvest 

methods were proposed, transects were walked and information taken to determine the numerical extent 

of existing compaction, as a percentage of the transect distance. In many units, no formal transects were 

taken as it was readily apparent that existing compaction amounts were no more than a few percent of the 

unit area. 

C. RESULTS

Anticipated direct effects to the soils resource will be within Willamette National Forest Standards and 

Guidelines. Recommended suspension requirements will control the potential for unacceptable 

displacement. Most areas with side slopes less than 30% will be recommended for ground based yarding 

systems. Compaction will be controlled by designated skid or forwarder roads (C6.41 and / or C6.42 –

LTSR), the use of existing truck roads as much as possible (to minimize the skidding distance and 

number of trips), and subsoiling. A few units may utilize processor falling and prebunching on side slopes 

from 30 to 45%, where the terrain is suitable and acceptable access is available. Skyline yarding with one 

end suspension will be recommended for units or portions of units with side slopes greater that 30% to 

avoid excessive disturbance from heavy equipment. Potential nutrient loss will be controlled by duff 

retention standards. Slope stability would be maintained by deleting those areas or units where harvest 

could result in unstable soil conditions. 
Hwy 46 Soils and Geology Report Page 3

The field investigation indicated that four units approached or exceeded the Willamette National Forest 

FW-081 Standard of 20% of an activity area impacted, in this case by compaction. It is likely with this 

proposed action that cumulative compaction in Units 70, 140, 190 and 250 will exceed the threshold at 

the completion of harvest activities. All the other proposed units had existing values which were 

sufficiently below to well below the threshold so that potential cumulative effects from an additional 

entry are likely not a concern. One of the goals with entry into the units that exceed the standard is to 

provide the opportunity to subsoil the existing skid roads as much as is practical in order to reduce 

compaction to lower levels. For the units mentioned above, subsoiling is a necessary mitigation to return 

soils to a less compacted state and to insure that cumulative levels remain below the 20% standard. The 

primary effort would be performed by the Purchaser / Logger, who would subsoil primary skid roads, 

landings or temporary haul roads used in the logging operations. 

In addition, some enhancement subsoiling (Purchaser or post sale) is recommended for many of the 

ground based units. This second phase could be post sale work that would be done on old skid roads and 

landings from this or previous entries. Potential units might include other ground-based units or portions 

of other units where both skyline and ground-based systems may be employed. The total enhancement 

work amounts to approximately 25 acres of additional subsoiling that is recommended to further reduce 

compaction. At about $1400 per subsoiled acre, this totals to around $35,000 of proposed enhancement

subsoiling. If some of these units are not included for harvest, or if sufficient enhancement funds are not 

present for all units, or if suitable access is precluded, then the dollars that are available will be distributed 

on a priority basis to the units with the greatest level of initial compaction, receiving the most attention. 

With entry into any ground-based area, evident skid or haul roads will be utilized before any new skid 

road is approved. 

Potential nutrient loss will be controlled by duff retention standards.

Potentially highly unstable and actively unstable terrain from both debris chutes and slump / earth flow

complexes are generally considered unsuited for timber harvest. If harvest is proposed, the primary 

objective on these lands is the maintenance of long-term slope stability. In this case thinning enhances the 

growth of leave trees and promotes a healthier stand with firmer roots and greater evapotranspiration 

activity. These factors contribute towards long term slope stability, and also provide larger wood to down 

slope areas should failure ever occur. 

Based on considerable field reconnaissance, 15 units (or portions thereof) - Units 5, 6 (Stand 2864), 12, 

25, 37, 38, 42, 53, 60, 77, 84, 93, 95, 100, and 290 - could have instability concerns. The primary 

objective on these lands is the maintenance of long-term slope stability. For Units 5, 6, 12, 53, 60, 84, 93, 

95, 100 and 290 potentially unstable, potentially highly unstable or actively unstable terrain is 

recommended for deletion from their respective boundaries. For Units 25, 37, 38, 42 and 77, controlled

thinning of potentially unstable areas is recommended to promote longer term stability. With the 

mitigations discussed in this report in place, potential slope instability with proposed management in any 

unit is not considered a concern. Conseqeuntly, no additional specific mitigation is proposed for thinning 

in the remaining manageable acreage. 

 

D. CONCLUSIONS

The soils design criteria / mitigation measures are designed to maintain long term soil productivity and 

provide a level of erosion control that is consistent with the standards and guidelines of the Willamette 

National Forest's Land and Resource Management Plan (1990) and Oregon State Department of 

Environmental Quality guidelines. All prescriptions or mitigation measures discussed in this report are 

designed to meet or exceed the requirements outlined in the National Best Management Practices for 

Water Quality Management on National Forest System Lands, Volume 1: National Core BMP Technical 
Hwy 46 Soils and Geology Report Page 4

Guide, USDA FS FS-990a, April, 2012. Prescriptions for soil protection and watershed considerations 

take into account past and predicted future land management activities. Standard contract language should 

provide sufficient erosion control measures during timber sale operations (BMP T-13). Revegetation of 

areas disturbed by harvest activities (such as landings, temporary roads, and equipment storage areas) is 

required with an appropriate seed mix (BMP T-14, T-15, and T-16). 

III. REGULATORY FRAMEWORK 

A. LAWS AND REGULATIONS -- 36 C.F.R. 219.28(a) directs the Forest Service to classify lands under 

their jurisdiction as not suited for timber production if they fall into any of three categories:

a. Legislatively or administratively withdrawn.

b. Irreversible soil or watershed damage (from NFMA 6(g)(3)(E)(i));

c. No assurance of reforestation within five years;

Elements b and c are the primary concern for this project. On the Willamette National Forest these areas 

are defined by landtype, which will be explained in more detail later in this report. 

B. NATIONAL DIRECTION: Forest Service Manual 2500 – Watershed and Air Management discusses 

the laws, executive orders, regulations, and Office of Management and Budget Circulars that are 

applicable to, direct or otherwise authorize watershed and soil management on lands of the National 

Forest System. In addition, the National Best Management Practices for Water Quality Management on 

National Forest System Lands, Volume 1: National Core BMP Technical Guide, USDA FS FS-990a, 

April, 2012 provides a guide on practices which are applicable in conducting land management activities 

to achieve water quality standards to ensure compliance with the Clean Water Act, as amended. 

C. REGIONAL GUIDELINES -- Forest Service Manual R-6 Supplement No. 2500.98-1 (Title 2520 

Watershed Protection and Management) clarifies direction for planning and implementing activities in 

areas where soil quality standards are exceeded from prior activities; redefines soil displacement; 

provides guidance for managing soil organic matter and moisture regimes, and provides direction to 

insure that activities meet applicable Oregon Administrative Rules. 

D. FOREST PLAN -- Chapter IV of the Willamette Forest Plan states the Forest-wide Standards and 

Guidelines for a variety of resources and activities. Soil and Water Quality protection are addressed in 

the section from FW-079 to FW-114. FW-079 in particular states “Land management activities shall be 

planned and conducted to maintain or enhance soil productivity and stability.” 

IV. SEQUENTIAL FLOW

Information, discussion and evaluation in this report are not linked to the analysis or modeling in another 

source area or report. The document is site specific unto itself. 

V. DESIRED FUTURE CONDITION

The major short-term impacts to soil productivity from harvest activity, as discussed in the Willamette 

National Forest Final Environmental Impact Statement (FEIS 1990), include displacement, compaction, 

nutrient loss, and instability. In most situations, preventing soil impacts is the most effective and feasible 

way of ensuring long-term soil productivity. The total area of cumulative detrimental soil conditions 

should not exceed 20% of the total acreage within the activity area, including roads and landings. 
Hwy 46 Soils and Geology Report Page 5

A. DISPLACEMENT --Displacement is defined as the removal of more than 50% of the topsoil or 

humus enriched soil horizons from an area of 100 square feet which is at least 5 feet in width. 

Displacement can occur with timber management during road or landing construction, yarding, or the 

mechanical treatment of slash, such as machine piling. Contract requirements which reduce or eliminate 

displacement are the primary way to minimize this concern. 

B. COMPACTION -- Compaction is defined as an increase in soil bulk density of 15% or more and/or 

by a reduction of macropore space of 50% over the undisturbed soil. Excessive soil compaction from 

heavy, mechanized equipment used during logging can decrease soil productivity by restricting root 

growth, reducing rainfall infiltration rates, and increasing over land flow and run off. Prior management 

on some units, conducted before any requirements were established, created compaction conditions which 

may now approach or exceed the currently accepted standards and guidelines. Activities which minimize 

further compaction such as skyline logging, utilize existing compacted areas as much as possible, or 

reduce existing compaction through mechanical means (subsoiling) are recommended. 

C. NUTRIENT LOSS --The primary mechanism for excessive nutrient loss is uncontrolled wild fire at 

high fuel loadings, low fuel moistures, and adverse weather conditions. Fire recurrence intervals of less 

than 100 years are apparent in the natural system, with shorter intervals in some critical high lightning 

areas or with suspected aboriginal burning. The actual thinning or harvest of these units is not as much 

concern for long term soil productivity as the concomitant slash accumulation and the potential for wild 

fire. On the other hand, NO ACTION IS NOT considered beneficial for long-term soil productivity either. 

Overstocked stands will rapidly see density increase, growth slow, and mortality rise. Fuel accumulations 

from blow down, snow down, and bug kill provide an ever increasing amount of fuel loading. Activities, 

which reduce stocking levels, improve stand vigor, and eliminate excessive fuel loading are favored. 

D. INSTABILITY -- Slope instability is also a natural ecological component of the Cascade Range 

ecosystem. Debris chute failure recurrence is generally associated with more episodic large fire and / or 

flood events. Slump / earth flow instability is more steady state and may extend for centuries. Slope 

failures of either type carry large wood and rock to stream systems. This material is needed to both create 

suitable structure for sediment storage and provide the gravels required for fish and other aquatic habitat. 

On the other hand, numerous failures, without the associated boulder or log structure, can overload a 

system with sediment and destroy functioning habitat. Activities which do not exacerbate existing 

unstable areas or promote long-term stability are favored. 

VI. ANALYSIS METHODS

Field work was conducted intermittently through the fall of 2012, all throughout 2013 and 2014, and 

intermittently in 2015. During that period, I conducted a field reconnaissance of potential harvest units 

and surrounding areas for this planned project in order to help implement Willamette National Forest 

program direction. Specific field days included August 27 and 29, September 15, 19, 20, 25, 27, 28, and 

29, October 3, 12, 22 and 23, November 13, and December 4 of 2012; April 16 and 29, May 6, 14, 20 and 

29, June 6 and 28, July 29, August 2, and November 1 of 2013; January 29 and 30, February 3, March 13 

and 17, April 17, and June 10 and 11 of 2014; and June 26 and July 31 of 2015. Also, several units, 

primarily along the existing power line transmission corridor, were investigated on the ground in the 

summer of 2012 as part of the Cascade Crossing reconnaissance. Finally, some additional field days were 

conducted in the late fall of 2015 as part of various engineering investigations, primarily for rock resource 

development or waste area considerations. 

A. FIELD INVESTIGATION STANDARDS
Hwy 46 Soils and Geology Report Page 6

A major portion of the field investigation was directed at distinguishing the various identifiable 

landtype components within the study area, related to the proposed units and surrounding area. 

Some of the landtype analysis referenced in this report was originally conducted for previous 

planning activities. In general, the field investigation confirmed most of the original 1973 SRI 

designations and the previously mapped work. However, more detailed work was conducted 

especially in some critical areas to better assess effects. The field work involved site specific 

evaluation of existing conditions within the units. My field investigation of the landtypes, the 

determination of the impacts from prior management activities (where appropriate), and the 

assessment of potential impacts from proposed future management, formed the basis for the sitespecific recommendations, design criteria, and/or mitigations that follow in this report. 

B. LANDTYPES -- Description and discussion

1. Unsuited and unmanageable landtypes have been delineated within the project area as part of the 

landtype mapping process (FW-180). Unsuited and unmanageable landtypes occur in two basic 

categories - those acres that are un-regenerable and those where harvest will cause irreversible impacts. 

Those landtypes that are considered to have regeneration difficulties (BMP T-20) could include 1, 2, 3, 4, 

5, 6, 7, 62, 210, 310, 610, and 710 or combinations of these landtypes. Almost all have numerous rock 

outcrops and cliffs, shallow gravelly soils with rock fragment content generally greater than 70%, and 

talus. Landtypes 6 and 7 are wet and dry meadows, respectively, and most areas of Landtype 6 are 

considered "wetlands" (BMP T-17 and W-3). All are currently considered noncommercial forestland or 

non-reforestable in the five-year time frame. Officially, 210, 310, and 610 are defined as marginally 

reforestable at least to extensive levels on easterly and northerly aspects, and non-reforestable in the fiveyear time frame on southerly and westerly aspects. However, almost no successful timber management 

has ever occurred on any aspect related to these specific landtypes on any Ranger District in the 

Willamette National Forest. Consequently, the north and east aspects of 210, 310, and 610 are considered 

unmanageable (no sufficient assurance of regeneration within the five year time frame) land in this report.

2. Landtypes considered unsuited because harvest will result in irreversible resource damage are primarily 

those that are actively unstable or potentially highly unstable (FW-105, BMP T-6). They could include 

the primary Landtypes 25 and 35, and the complexes of 255 (25 plus 35), 256, and 356. Landtypes 256 

and 356 have actively unstable areas very closely associated and generally in direct contact with stream 

riparian areas or stream courses. These areas all commonly display slump type topography and include 

such features as tension cracks, bare soil scarps, leaning and fallen trees, sags and depressions, seeps, and 

disrupted drainages. Failure depths are such that root strength probably has little effect. However, the 

instability problem can be aggravated by timber harvest, as removing the trees tends to raise ground water 

levels due to the loss of evapotranspiration. This in turn reduces the soil strength and can cause increased 

or renewed instability. On the other hand, thinning these areas can create thriftier stands that have greater 

root strength and increased evaporation over time. Other landtype complexes that contain elements of 25 

or 35, such as 225, 235, 251, 252, 253, 254 and 353 need to be evaluated on a case-by-case basis as 

management activities are proposed.

3. Landtype complexes, such as 13-212, 55-233, 201-212, or 201-204 have elements of both landtypes 

that were either not differentiable at the photo scale, or sufficient field time was not available to 

distinguish the various components.

4. The remaining landtypes are adequately discussed in the Willamette National Forest Soils Resource 

Inventory. This document, first developed in 1973, was made to provide some basic soil, bedrock and

landform information with management interpretations in order to assist forestland managers in applying 

multiple use principles. For this project, the 1973 definitions were utilized with updated and more detailed 
Hwy 46 Soils and Geology Report Page 7

landtype mapping. A copy of the original text and mapping is on file with the Natural Resources Staff 

group at the Detroit Ranger District, and a digital copy of the mapping is on file as a file geodatabase 

within the Willamette National Forest corporate GIS reference library.

C. BASIS FOR EVALUATING EFFECTS

For the soil resource the scale of analysis for both direct / indirect effects and cumulative effects is almost 

always the “unit”, i.e. the stand polygon or activity area proposed for silvicultural treatment. The unit of 

measure for evaluating those effects is generally considered the percent of the “unit” affected. The 

summing of acres for various units, such as the total acres of skyline logging in a given alternative, is not 

an evaluation criterion for soils impacts. Impacts are evaluated on a unit-by-unit basis, and are generally 

the same in any given unit for all action alternatives, unless otherwise noted. 

All action alternatives and the no-action alternative will be evaluated for impacts to the soil resource. In 

this analysis, all the action alternatives have the same basic effects and the same soil protection measures, 

as described on a unit-by-unit basis, and will be considered similarily. Evaluating impacts and their 

potential significance between or among alternatives requires a discussion of the duration and intensity of 

those impacts. Often various words are utilized to describe those conditions. The following definitions 

apply to impacts described in this report: 

1. Duration 

- Short-term: The effects last for a few weeks to one or two years;

- Intermediate: The effects last from one or two years to about a decade:

- Long-term: The effects last from about 10 years to several score years or longer.

2. Intensity

- Low, negligible, little or no, minimal, minor: The impacts are essentially zero, at the lowest levels of 

detection, or very slight. They may or may not be noticeable.

- Moderate, reasonable: The impacts are readily apparent, but meet standards and guides.

- Excessive, substantive, major, critical: The impact is moderate to severe and likely approaches the upper 

limits of standards and guides. 

- Significant, unacceptable: The impacts are severe, and likely exceed standards and guides or do not meet 

Best Management Practices. 

VII. EXISTING CONDTION AND ENVIRONMENTAL CONSEQUENCES 

A. INTRODUCTION

The Breitenbush watershed is located above Detroit Reservoir and has a total area of about 69,400 acres, 

almost all of which is located on the Willamette National Forest. (The Mt. Hood National Forest also has 

a small amount). This project area contains both High Cascade and Western Cascade physiographic 

provinces. The dividing line runs approximately south and northeast from the area of the confluence of 

the North and South Forks. The following discussion is based on information provided by Hammond, et 

al, 1980; Peck et al, 1964; Ricker, 1982; and Walker and Duncan, 1989. 

Most of the proposed units in this project area are located within the Western Cascades physiographic 

region, on strata that were once called the Little Butte Sequence. Much of this area has been remapped by 

Walker and Duncan (1989) as “Tu”. The project area lies at the eastern boundary of their mapping area 
Hwy 46 Soils and Geology Report Page 8

and also extends east beyond it. “Tu” includes undivided Miocene and Oligocene tuffaceous sedimentary 

rocks, basalt flows, tuffs and breccias form the foundation for most West Cascade drainages (Walker and 

Duncan, 1989) in this area. The strata often consist of a heterogeneous assemblage of continental, largely 

volcanogenic deposits of basalt and basaltic andesite, including flows and breccias, complexly 

interstratified with epiclastic and volcanoclastic deposits of basaltic to rhyodacitic composition. They 

also include extensive rhyodacitic to andesitic ash-flow and air-fall tuffs, abundant lapilli tuff and tuff 

breccia, andesitic to dacitic mudflow (lahar) deposits, massive to bedded, fine to coarse grained, 

tuffaceous sedimentary rocks, and volcanic conglomerates. Radiometric potassium/argon dates on parts 

of this formation are mostly 32 to 17 million years old (Walker and Duncan, 1989). 

Overlying these older formations just mention, the higher elevation main ridges are capped with flows 

and flow breccias of olivine andesite, basaltic andesite, and some basalt. These rocks, the “Tba” of 

Walker and Duncan (1989) have previously been designated as the Sardine Formation by some authors 

(Peck, et al, 1964). These flow deposits lie in an unconformable position on the older Tertiary deposits 

and erupted mostly from widespread, northwest trending dikes and dike swarms and related plugs and 

lava cones. Their potassium-argon age dates range from about 17 to 10 million years ago or Middle to late 

Miocene (Walker and Duncan, 1989). 

Overlying these upland volcanic deposits are even younger, ridge capping basalt flows, the “Tb” of 

Walker and Duncan (1989). A few proposed units appear to be located on these strata. Some volcanic 

flows of this unit are lithologically similar to flow rocks of the High Cascade volcanic sequence and some 

are more like flows that were previously mapped as part of the Sardine Formation. Potassium – argon 

ages of rocks of this unit range in age from about 10 to 4 million years (Walker and Duncan, 1989).

The High Cascades portion on the eastern side of the project area contains the youngest volcanic rocks of 

the Cascade range, mostly Pliocene or Pleistocene in age. Some of the oldest lava flows of the High 

Cascades appear to have covered the youngest Western Cascade strata. Since then, most volcanic events 

have generally been confined to the High Cascades proper (Hammond, et al, 1980). Most of the High 

Cascade volcanic eruptions, which form the broad base of the High Cascade platform, contain basalt 

flows, flow breccias, and pyroclastic deposits. They represent the early part of the volcanic eruptions, and

their ages range from about four to one million years. The youngest and most recent deposits are 

generally less than one million years in age and include intra-canyon flows, low shield volcano out 

pouring, and the more pronounced stratacone deposits, like those on Mount Jefferson or Three Fingered 

Jack (Walker and Ducan, 1989) (Hammond, P. E., et al, 1980). 

In the last several million years, all these rock formations have been extensively modified by stream 

erosion, mountain glaciation and slope instability (Ricker, 1982). The surface expression of these rock 

formations has been extensively altered by erosion since late Pliocene time, especially with Pleistocene to 

Holocene glacial activity and large scale slope instability. The upper Breitenbush drainage was likely 

heavily affected by the large ice cap glaciers that covered the High Cascade platform with sheets of ice 

hundreds of feet thick. During numerous glacial periods, large valley glaciers surged away from the 

Cascade crest and traveled west down the main drainage. The drainages of the High Cascades are 

typically U-shaped, glaciated valleys with flat valley bottoms and steep rocky valley walls that abruptly 

transition to rolling uplands at the higher elevations. More recent late Pleistocene glaciations were likely 

much smaller, and localized valley glaciers carved smaller cirques on the north aspects of these same 

stream uplands. 

The rocks and strata of some of the older Tertiary volcanic deposits (usually the “Tu” strata) sometimes

weather to form deep colluvial and residual soils that can give rise to unstable soils. Stabilized slump / 

earth flow features, such as sag ponds, bench and scarp topography, and disrupted drainages are common 

in many parts of this project area. It seems likely that slump / earthflow instability has been a significant 
Hwy 46 Soils and Geology Report Page 9

factor in slope development and stream channel morphology for the last several thousand years, certainly 

since the end of the Pleistocene. However, large scale slope instability from slump / earthflow complexes 

and debris chutes has been relatively inactive in the last 500 to 1000 years or more, except in some 

localized areas. 

This complex relatively recent geologic history has produced a myriad of diverse landforms and soils. In 

general soils on these side slopes have been stable and productive for at least several hundreds of years. 

Soils formed either directly on the underlying volcanic bedrock, on the more limited glacial deposits, or 

on jumbled combinations of the two in the slump complexes. Both types have similar size gradations that 

range from silt loams to gravelly or cobbly, sandy loams. Depth to bedrock is highly variable and can 

range from a few feet to many times that amount. The various landtypes are generally well drained where 

permeability is rapid in the surface soils, and rapid to moderate in the subsoil. Because of high infiltration 

rates, overland flow is generally uncommon. In the proposed units, side slopes range from near zero to 

about 80%, but are generally less than 60%. Offsite erosion is generally not a concern because of the 

extensive vegetative ground cover and the gentle to moderate side slopes. 

Stand ages in this project area are somewhat variable and indicate that natural or human caused fires were 

very prevalent in the last couple of hundred years. There is some evidence that under burning happened in 

older stands when stand replacement fires occurred in nearby areas. Other areas were not burnt or 

underburnt in the extensive stand replacement fires that traveled through much of the District 

approximately 150 to 500 years ago. It is likely that aboriginal or natural fires were common along the 

ridge lines in this project area prior to settlement by Europeans. As a result, natural accumulations of 

down woody debris are highly variable across many areas.

Similar discussions parallel those mentioned in the last paragraph with decades of timber management. 

Some of the older plantations with lower utilization standards retained considerable large down woody 

debris. Younger plantations, with PUM or YUM yarding and higher utilization standards, removed much 

of this type of material. Older slash burns, with late summer or fall burns, consumed considerable 

amounts of the above ground organic matter. Younger slash burns generally conducted with more “spring 

like” conditions, retained much of the larger material. The most recent plantations, which had down 

woody debris objectives, again began to accumulate larger material on the ground. Consequently, a wide 

range in the above ground tonnage of decomposing organic matter now exists among the various 

plantations.

B. DIRECT AND INDIRECT EFFECTS

The major short-term, intermediate, or long-term impacts to soil productivity from harvest activity, as 

discussed in the Willamette National Forest Final Environmental Impact Statement (FEIS 1990), include 

displacement, compaction, nutrient loss, and instability. In most situations, preventing soil impacts is the 

most effective and feasible way of ensuring long-term soil productivity. The following sections discuss 

in more detail (1) how the proposed action may affect the soil resource or (2) design criteria that can be 

utilized to avoid potentially undesirable effects. 

1) No Action Alternative

 Stands will continue to develop. Many of the stands proposed for treatment currently have little 

understory vegetation because of the lack of sunlight to the forest floor. Intermediate and suppressed trees 

would slowly be removed from the stand through mortality and decay. In areas of heavy stocking, stands 

would stagnate. Blow down and snow down would continue to increase fuel loading in the short to 

intermediate term. The likelihood of a stand replacement fire would increase. Uncontrolled wildfire at 

high fuel loadings and adverse weather conditions could produce moderate to high severity burns across 
Hwy 46 Soils and Geology Report Page 10

much of the landscape. Global climate change could alter the capacity of some stands to continue to carry 

the current density of trees in a healthy manner. Some stands in the intermediate to longer term could 

begin to exhibit substantive mortality. 

In general, plant diversity would diminish as well as soil biota because of the lack of sunlight. In areas 

already compacted or disturbed, the soil building process will continue to return the soil to near 

preharvest conditions in the longer term. Short-term to intermediate term impacts from harvest, such as 

soil disturbance, dust (or mud), slash accumulation and disposal, and longer term impacts such as 

compaction and nutrient loss would not occur. 

Slope instability is a geologic process that is currently active in parts of this project area and can 

potentially affect some proposed units. Most potentially actively unstable or potentially highly unstable 

soils were deleted from the units in the action alternatives. Consequently, in the short or intermediate 

term, no effects to slope instability are anticipated whether the units are managed or not. Stand density is 

such that little change in stability is anticipated in the short to intermediate term. In the long term, loss of 

stand integrity with disease, storm or fire might cause an increase in slope failure. 

 2) All Action Alternatives

All action alternatives have the same basic effects and the same soil protection measures, as 

described on a unit-by-unit basis. Some units may be evaluated that do not end up being 

considered in any action alternative. They are included to document the work that was 

accomplished. 

A. Displacement

a) Existing Condition

Displacement occurs with three separate timber harvest activities: yarding, slash treatment, and 

road building and maintenance. Yarding activities involve the movement of wood from the unit to 

the landing, and yarding on the existing plantations has for the most part occurred with the 

appropriate suspension requirements. Suspension requirement refers to the amount of the tree 

suspended above the ground during the in-haul of the log to the landing. Slash treatments usually 

maintained some amount of duff, though the current duff retention standards may not have been 

achieved decades ago. Some of the oldest managed stands may have been tractor piled. Tractor 

piling can result in both excessive disturbance and excessive compaction. Whether these two 

activities resulted in moderate to major detrimental impacts to productivity in some units is 

difficult to determine. Tractor piling with a dozer and brush rake has NOT been considered 

acceptable as a management tool for over 25 years on the Willamette National Forest. Within this 

project area, many side slopes are too steep for any type of ground based equipment. Stand, shrub 

and brush growth, as well as duff accumulation over the decades, have provided an effective 

ground cover. At the point in time, little physical evidence can be found in any unit to indicate 

whether these two timber management activities resulted in significant, long-term detrimental soil 

displacement, off-site soil movement, or substantive loss of productivity. 

Even though road development in this project area is extensive, several blocks of forest have not 

yet been accessed. Most major road systems were constructed in the 1950s to the 1970s with 

older road construction standards when few location and construction controls were in place. 

Some of these roads were built on steep side slopes with side cast construction standards, where 

most of the excavated material was pushed or blasted over the edge onto the steep side slopes 

below. The remnants of this side cast, such as bare soil scarps and rocky talus zones, are still 
Hwy 46 Soils and Geology Report Page 11

evident in a few areas. Several road locations cross actively unstable or potentially highly 

unstable soil areas where roads have failed over the years and been repaired.

The amount of new road construction slowed considerably in the late 1980s, and with subsequent 

entries, reconstruction began to dominant. Newer roads, when required, were constructed to 

different and better standards. Road grades were steepened and pitched to better fit the road 

template to the terrain. Side cast was eliminated, and end haul of excess excavation to stable 

waste sites or designed fills was required. Cuts and fills were minimized, and drainage controls 

were added to promote long term slope stability. Newer spurs, when utilized, were often 

constructed on benches, flats and gentle side slopes. Most road cuts and fills have naturally 

vegetated over the years. Because the side slopes have revegetated and overland flow is limited 

throughout much of this project area because of the high infiltration rates, erosion from roads is 

not generally considered a concern, except in a few localized areas where side cast roads parallel 

nearby perennial drainages. 

b) Environmental consequences

NOTE: Recommendations are the minimum suspension requirements for adequate soil resource

protection. Some units may be helicopter logged to avoid expansion of the existing transportation 

system, or to achieve acceptable protection for resources other than soils. In no case is helicopter 

yarding considered a soil protection or mitigation measure. Some potential ground based areas

may be fully cable or skyline yarded to avoid having ground based equipment working under 

skyline corridors. 

The logging suspension requirement for a proposed unit is mandated in the Land and Resource 

Management Plan to protect the soil from excessive disturbance or displacement (FW-107 and BMP T12). With cable systems, the area near tail trees and landings (usually about 100 feet) is excluded from 

this suspension constraint. Unless otherwise stated or mitigated, all designated streams require full 

suspension or yarding away from the stream course during the yarding process (MA-15-27). To 

adequately protect the soil resource, the primary yarding objective for all units will be either ground based 

systems with predesignated skid roads and directional falling as appropriate, or skyline yarding with one 

end suspension, except at tail trees and landings. The primary factor differentiating these two yarding 

systems will be side slope. Some cable yarding, skyline use without one end suspension, is acceptable on 

some slopes, especially where small amounts of timber may be winched to nearby roads, or where 

intermediate benches or small ridges may be rubbed on a predominately, one end suspension skyline 

corridors. In addition, some units (or portions thereof) may be helicopter yarded to minimize 

development of the transportation system that would be needed for more conventional logging systems. In 

this case, the helicopter yarding is not needed for increased soil protection. 

Ground-based yarding systems may be employed on those acres in each unit where slopes are gentle 

enough (generally 30% or less) for ground-based systems. Ground based yarding systems, such as 

processor / forwarder, skidding with conventional line pulling or shovel, could be utilized in many units. 

All areas where ground based yarding might occur, are well away from active drainages, or skid roads 

will cross ephemeral swales only during dry periods and at right angles. All ground based yarding will 

require that either C6.41 and/or C6.42 (predesignated and preapproved / LTSR) contract clause(s) on 

ground based portions be strictly adhered to, and/or line pulling and directional falling will be 

implemented, as appropriate. In all cases, existing skid or haul roads will be utilized before any additional 

new skid or forwarder roads are developed. 

During actual operations, ground based yarding may be allowed on side slopes greater than 30% 

but less than 40% in a few selected instances where it is determined that yarding on these steeper 
Hwy 46 Soils and Geology Report Page 12

slopes is more beneficial to the various resources than implementing some other logging system. 

Determining factors will include a site specific evaluation in the field by Forest Service 

personnel, the operational period and current (and expected) weather conditions, and the ability of 

the operator / contractor to implement the work successfully and safely. 

Prebunching occurs when processor falling is used to cut and orient fallen timber so that either helicopter 

or skyline logging systems are can more efficiently bring the wood to the landing. Prebunching makes 

these logging systems much more cost effective. By definition, prebunching does not occur on slopes less 

than 30% - where ground based equipment is already allowed. As an operative constraint, prebunching is 

allowed only on side slopes less than 45%. All prebunching areas have the same access requirements that 

ground based logging must adhere to. In other words, all cutting equipment roads must be predesignated 

and approved prior to use (C6.41 and / or C6.42 – LTSR).

Skyline yarding with one end suspension will be recommended for units or portions of units with side 

slopes greater that 30% to avoid excessive disturbance from heavy equipment. Skyline operations in 

thinning units with small wood and intermediate supports usually impacts less than 1% of the unit area. 

Most of the units with steeper ground had little or no existing disturbance levels. Some road work, either 

with temporary spurs or reconstruction might be required in some units to access suitable landing sites. 

c) Conclusions and Rational

At the point in time, little physical evidence can be found in any unit to indicate displacement from 

previous management activity has been a problem. Disturbance from yarding will be well within the 

Regional and Forest standards, and significant adverse impacts are not anticipated. With appropriate 

suspension during logging, soil disturbance is minimal and off site erosion is essentially non-existent. 

During harvest, the retention of stream adjacent trees and the requirement of full suspension yarding over 

or away from stream courses will minimize or eliminate off-site erosion. 

B. Compaction

a) Existing Condition

The major source of compaction (and also much disturbance) is ground based skidding equipment. 

Unrestricted tractor yarding and tractor piling are not considered an option on those landtypes where 

sideslopes are gentle enough (generally less that 30%) to support tractor usage (BMP T-9 and VM-1, and 

FW-107). Restricted tractor yarding from predesignated skid roads (C6.41 and/or C6.42 (predesignated 

and preapproved / LTSR contract clause) is considered an option if the adversely affected area remains

less than 20% of the activity area (BMP T-11). With tractor yarding, skid roads are predesignated -

approved in advance of use by the Timber Sale Officer and generally 150 to 200 feet apart. With a 

processor/forwarder system the skid roads are usually only about 50 to 60 feet apart, but the number of 

trips for each individual road are substantially less than with skidding. 

Extensive monitoring over many years has also shown that when designated skid roads are properly 

utilized in conjunction with line pulling and directional falling, compaction from ground-based tractor 

operations generally remains at about 9 to 13%. Residual compaction from the original harvest of these 

plantations needs to be considered. In units with existing compaction, when old skid roads are reused and 

some subsoiling is implemented, monitoring has again shown that over all compaction levels at the 

completion of management activities generally remain around 12 to 16%. 

Reducing the effective weight of the tractors and reducing the number of trips over a piece of ground are 

other means to reduce the risk of soil compaction and displacement. Yarding over frozen ground or over 
Hwy 46 Soils and Geology Report Page 13

a deep, solid snow pack (24 inches of dense snow or equivalent) also substantively reduces soil 

disturbance and compaction (BMP VM-4). Over-the-snow yarding is encouraged for any of these units, as 

long as other resource objectives can be achieved, and sufficient snow accumulation is available. 

Monitoring of previous over-the-snow operations on various Districts has shown that essentially no 

displacement or compaction occurs, when it is properly implemented. 

b) Environmental consequences 

Evidence of compaction from previous entry is still present. Field reconnaissance of the proposed units

shows some level of existing compaction, primarily associated harvest within the existing plantations. 

Oriented transects were walked through the larger portions of possible ground-based units. Transects 

were usually about 300 to 1000 feet in length. The results of the field investigation follow this 

paragraph. In no case was the technical degree of soil compaction measured directly. In other words, 

absolute changes in soil bulk density or reduction in macropore space were not measured. Instead, heavily 

disturbed skid roads, landings or other areas where equipment tracks were evident are considered 

adversely compacted.

Transects measure the amount of compacted ground along a line within a proposed unit. The total width 

of these areas was used to determine the amount of compaction by transect distance. They were generally 

oriented to obtain information on previous management activities. They are not random, nor statistically 

representative of a particular unit. However, they do provide a strong indication of the degree of concern 

for the unit under investigation. In some cases, multiple transects were walked in different directions in 

order to provide more information, or to monitor and evaluate the initial results for accuracy. Ranges 

indicate some degree of uncertainty in the presence of compacted skid roads because of brush or other 

factors. 

Unit No. Percent compacted along an individual transect, or other discussion

6 Little existing compaction in the flatter areas. 

17 Estimated at 10% - mostly haul roads and landings. 

23 Estimated at 8 to 10%, mostly haul roads and landings. 

31 One transect: 500 ft at 8 to 10%.. 

35 One transect: 1500 feet at 13 to 14% (mostly truck roads as much of unit was cable). 

51 Little existing compaction observed. 

55 Little existing compaction observed.

56 Little existing compaction observed.

57 Little existing compaction observed.

58 Little existing compaction observed.

59 Skid roads not well developed – compaction is questionable. 

60 One transect: 600 feet at 5%.

61 Transect in flatter area: 700 feet at 10 to 11%. 

63 One transect: 800 feet at 13% to 15%; skid roads somewhat confusing on the ground. 

70** One transect: 400 ft at 20%.

73 Two transects: 800 feet at 12% and 400 feet at 11% - Compaction excludes system roads 

and old rock quarries. 

74 Estimated at 10%, mostly includes haul roads, landings and rock development. 

78 Little existing compaction. 

85 Little existing compaction. 

89 Little existing compaction. 

140** One transect: 1200 feet at 22%.

140A Portion north of road – estimated at 10 to 12%, mostly old haul roads and landings. 
Hwy 46 Soils and Geology Report Page 14

150 Little existing compaction observed – estimated at 3% or less. 

180 Two transects: 10% for 300 feet, and 16% for 600 feet. 

190** Two transects: 500 ft at 28%, and 1000 ft at 25%. 

220 One transect” 400 ft at 10%. Some localized areas of heavier compaction. 

250** Two transects: 300 ft at 20%, 250 ft at 20%.

360** One transect: 300 feet at 20% +, above road on ridge line. 

370 Two transects: 500 ft at 10%, and 300 ft at 10%. Compaction excludes system roads, 

landings and waste areas. 

430 Little existing compaction. 

450 Little existing compaction observed – estimated at 3% or less.

500** Estimated at 12 to 20%+ - depends on layout. Unit dropped. 

520 Three transects: 700 ft at 14 to 15%, 800 ft at 13%, and 900 ft at 14%. 

540 Little existing compaction observed – estimated at 3% or less.

580** Estimated at 12 to 25%+ - depends on layout. Unit dropped. 

The field investigation indicated that several units approached or exceeded the Willamette National Forest 

FW-081 Standard of 20% of an activity area impacted, in this case by compaction. These include 70, 140, 

190, and 250. In Unit 360, the area above the road on the ridge had higher compaction, but the bulk of 

the unit was skyline with very little existing compaction. Units 500 and 580 were dropped from 

consideration. All the other proposed units had existing values which were sufficiently below to well 

below the threshold so that potential cumulative effects from an additional entry are likely not a concern.

One of the goals with entry into the units that exceed the standard is to provide the opportunity to subsoil 

the existing skid roads as much as is practical in order to reduce compaction to lower levels. 

It is likely with this proposed action that cumulative compaction in Units 70, 140, 190, and 250 will 

exceed the threshold at the completion of harvest activities. Subsoiling is a necessary mitigation to return 

soils to a less compacted state and to insure that cumulative levels remain below the 20% standard. Based 

on previous experience, this effort should be successful. For example, past postharvest subsoiling in units

on this and other Districts has reduced the overall compaction level about 4 to 8% from initial values. In 

order to be successful in lowering compaction totals, an absolute requirement is that, with entry into any 

ground-based area, evident skid or haul roads will be utilized before any new skid road is approved. 

At the completion of harvest activities, mitigation subsoiling is required for Units 70, 140, 190 and 250 in 

order to reduce compaction levels and improve overall productivity. The primary effort would be 

performed by the Purchaser / Logger, who would subsoil primary skid roads, landings or temporary haul 

roads used in the logging operations. In addition, some enhancement subsoiling (Purchaser or post sale) 

is recommended for many of the ground based units. This second phase could be post sale work that

would be done on old skid roads and landings from this or previous entries. Potential units might include 

8, 9, 10, 17, 23, 31, 35, 56, 57, 58, 59, 61, 63, 70, 73, 74, 78, 140A, 150, 180, 220, 450 and 520 or 

portions of other units where both skyline and ground-based systems may be employed. Of these, the 

highest priority are Units 35, 63, 73, 180 and 520. 

The total enhancement work amounts to approximately 25 acres of additional subsoiling that is 

recommended to further reduce compaction. At about $1400 per subsoiled acre, this totals to around 

$35,000 of proposed enhancement subsoiling. If some of these units are not included for harvest or if 

sufficient enhancement funds are not present for all units, or if suitable access is precluded, then the 

dollars that are available will be distributed on a priority basis to the units with the greatest level of initial 

compaction, receiving the most attention. 

c) Conclusions and Rational
Hwy 46 Soils and Geology Report Page 15

In summary, with the use of designated skid roads, the reuse of the existing skid road system, and the 

subsoiling of landings and primary skid roads, compaction is not anticipated to exceed the 20% value in 

any unit, except Unit 190, and should generally be below the 15% level (or much lower). The objective is 

to bring these units into compliance with the current standards by reducing overall compaction below the 

20% level. Based on previous experience, this effort should be successful. However, in Unit 190, the 

overall compaction will certainly be reduced from prethinning levels, but the 20% objective may or may 

not be achieved. This situation might develop in order to limit the amount of root pruning of leave trees 

and/or to avoid excessive amounts of exposed soil. 

Units will be monitored as needed during project implementation, and those units with the highest initial 

compaction levels will be the highest priority for post sale subsoiling dollars. This entry will reduce the 

overall compaction in most units. It is possible that compaction levels in a few units could still approach

or exceed the Forest standard at the completion of management activities, but the end result is that 

adverse effects to these units would be lower than prior to entry. 

It should be noted that the use of temporary truck roads considerably reduces the amount of compaction 

for most units by reducing both the number of trips across the ground and shortening the skidding 

distance. I strongly encourage the use of the existing road system in the area and the potential to create 

new temporary truck roads on the relatively flat ground in order to reduce soil compaction. Given that, 

essentially all newly created, temporary truck haul roads should be subsoiled at the completion of harvest 

activities. Subsoiling may be curtailed in some areas in order to reduce the amount of root pruning of 

leave trees, to avoid excessive amounts of exposed soil, or to avoid stumps or large rocks. 

Skyline operations in thinning units with small wood and intermediate supports usually impacts less than 

1% of the unit area. Skyline yarding with one end suspension is proposed for part or all of most units. In 

no case is helicopter yarding recommended as a soil protection measure. Helicopter usage may be 

planned to reduce the development of the transportation system required by conventional logging 

methods, or for other resource protection. Transects in skyline areas on side slopes from 25 to 50%, as 

well as extensive field reconnaissance of the steeper ground in almost all other units, indicates that these 

units had relatively low existing compaction levels. Consequently, cumulative effects from existing 

compaction and skyline yarding are not anticipated for any unit. 

C. Nutrient Loss

a) Existing Condition

Many of the natural stands in this project area have had an active fire history in the last 50 to 150 years. 

Often, large expanses never had much down woody debris, or all of the accumulating down woody debris 

was removed by the fires. On the other hand many of the more recent fires, as well as blow down, bug kill 

and snow down, have created areas with considerable down timber. As a result, a wide range in the above 

ground tonnage of decomposing organic matter exists.

Duff Retention objectives were specifically developed many years ago by the Willamette National Forest 

to apply to clear cut harvest prescriptions with broadcast burns on various landtypes with differing surface 

soil erosion potentials. Duff retention is the amount of duff thickness remaining after management 

activities are completed. For example, if average premanagement duff thickness was one inch, and 

approximately one half inch remained after broad cast burning, then duff retention would be 50%. When 

these standards were developed, duff retention on partial cut harvest prescriptions was not a significant 

issue, and none were formulated. Also, duff retention for specific restoration or silvicultural objectives, 

such meadow burning or the natural regeneration of Sugar pine or some other species, may be less to 

much less than what might be prescribed for a specific soil and side slope independently. 
Hwy 46 Soils and Geology Report Page 16

Monitoring and field reconnaissance in recent years has shown that the duff retention percentages for 

under burns in partial cuts, thinnings, or fuels reduction within unmanaged stands, which maintain an 

intact live root mat and live canopy cover over most of the unit, could be less (to much less) and still 

achieve adequate soil protection. Having said that, actual duff retention measurements on under burns

(both natural and management directed) on various Districts in the last several years indicate that the 

“broadcast burn” standards for duff retention are generally achieved, even if they are not specifically 

required. Consequently, they serve as a good goal and are generally recommended as a desired objective 

for the units in this report, unless other restoration purposes override these intentions. 

b) Environmental consequences 

In the unit summary section, objectives for duff retention will be specified for each unit. For all action 

alternatives slash will be scattered in the units, piled and burned, or perhaps broadcast or under burned. 

Piling may occur by hand or with a grapple machine. Grapple piling occurs with a grapple not with a 

dozer brush rake. Grapple piling requires only one pass of the machine across the landscape, and the 

machine works while sitting on slash. Extensive monitoring of grapple machine piling operations 

indicates that little or no additional compaction or displacement occurs, when properly implemented. On 

typical thinning, hand piles number about 40 per acre and occupy about 20 square feet per pile for a total 

of about 800 square feet per acre or about 1.8% per acre. Machine piles are substantively less in number, 

but correspondingly larger in size so that the 1.8% to 2% figure is maintained. In many cases only a few 

acres of any particular unit are hand piled or machine piled. Burning the piled slash may develop 

sufficient heat to affect the underlying soil. However, pile burning is usually done in the fall or winter 

months when duff and soil moistures are higher, and this helps reduce the downward heat effects to the

soil. Consequently, pile burning is considered a minor effect and not cumulative because of the limited 

overall acreage involved.

Another aspect of long term nutrient availability and ectomycorrhizal formation is the amount of larger 

woody material retained on site. Management activities will be planned to maintain enough large woody 

debris (dead and down) to provide for a healthy forest ecosystem and ensure adequate nutrient cycling 

(FW-085). At this time, site specific needs will be considered commensurate with wildlife objectives as 

outlined in FW-212a and FW-213a (as amended). No additional large down woody debris is required 

from a soil management perspective. 

c) Conclusions and Rational

In summary, duff retention objectives will be provided on a unit-by-unit basis in the unit summary table. 

Consequently, with the retention of adequate duff and woody debris, potential adverse impacts to longterm soil productivity are not anticipated. 

D. Instability

a) Existing Condition

As was stated previously, the Breitenbush drainage is generally considered a moderately stable to very 

stable basin when compared to the more actively unstable basins within the West Cascades, such as the 

Blowout. However, active slope instability from both debris chutes and slump / earth flow complexes 

does occur in most subwatersheds. 

Potentially highly unstable and actively unstable terrains are now considered unsuited for timber harvest. 

If harvest is proposed, the primary objective on these lands is the maintenance of long-term slope 
Hwy 46 Soils and Geology Report Page 17

stability. In this case thinning enhances the growth of leave trees and promotes a healthier stand with 

firmer roots and greater evapotranspiration activity. These factors contribute towards long term slope 

stability. 

Based on considerable field reconnaissance, 15 units (or portions thereof) could have instability concerns. 

They will be discussed as follows. Because it makes more sense, design criteria and/or mitigations will 

be included with each unit instead of stating everything again in the next section of this report (as is 

generally required). 

Unit 5: Road 4698, the upper boundary, was built with extensive side cast construction. Small debris 

chute type failures have dropped off this edge over the years. Also numerous trees have lean and pistol 

butt. The larger edge trees along this boundary (one to three rows) should be retained as much as possible 

to stabilize the side cast material. Also, a road sag at milepost 0.45 defines the upper boundary of an

active slump. About one acre of alder or mixed hardwood and conifer should be deleted in the unit below 

the roadway.

Unit 6: Potentially to highly unstable terrain, as well as small cliffs and talus areas, are located below Rd 

4698 near the north boundary at the center of the unit. This area should be deleted at layout from the road 

down to the bottom of this area. In addition, potentially unstable slopes on the sharp slope breaks along 

the far south boundary into Fox Creek should be included with the riparian area and deleted at layout. 

The harvest of Unit 6 as a thinning, will not adversely affect slope stability on the ground south of this 

unit. 

Unit 12: The rocky and potentially; unstable area along the northeast boundary at the creek should be 

included in a wider stream buffer and deleted at layout. The boundary would generally be at or above the 

major slope break in this area. Geology can assist in layout if needed. The harvest of Unit 12 as a 

thinning, will not adversely affect slope stability below this unit. 

Unit 25: This unit has or had stable soils. Areas of potentially unstable ground developed because of old 

tractor logging on very steep side slopes as part of the original power line clearing. Root strength from the 

natural regeneration has stabilized most sites. The recommendation is to thin to 50% canopy closer and D 

X D spacing. No gaps should be placed in the critical areas. Some of these areas above the creek should 

be included in a wider stream buffer and deleted at layout. With that, the harvest of Unit 25 as a thinning, 

will not adversely affect slope stability on the ground below the unit boundary. 

Unit 37: Most of this unit is located on a semi-active earthflow that toes out in Short Creek. This unit is a 

plantation that was cut on an actively unstable area. This area is considered unsuited for timber 

management, and the objective with entry is thinning for long term stability. The recommendation is to 

thin with D x D to about 50% canopy cover. No gaps should be placed in this unit, and all trees 18 inch 

dbh or larger should generally be retained regardless of spacing, except in yarding corridors or as needed 

to be cut to facilitate operations. 

Unit 38: Most of this unit is stable. Small areas of this unit (a few acres) along the west boundary on 

either side of the rocky exclusion (the slump scarp addressed in Unit 37) may be in the unstable area. It is 

recommended that these small areas would best be included with Unit 37 during layout, and managed as 

part of the Unit 37 prescription. The remainder of the unit, west of the slope break or ridge line, should 

be designated as a moderate thin with no gaps. Gaps or heavy thinning should be placed on the flatter 

ground east of the ridge line. 

Unit 42: A small part (a few acres) of this unit along the east boundary contains the Mansfield Slide, 

which occurred in March of 1982. The slide area has now mostly stabilized, and the recommendation is 
Hwy 46 Soils and Geology Report Page 18

thin this portion of the unit to maintain and enhance long term stability. The recommendation is to thin 

this area with a 50% canopy closer and no gaps. No ground – based harvest or prebunching should occur 

in this area. The remainder of the unit is on stable ground. 

Unit 53: This unit contains two streams, both of which fork in the upper part of the unit. All four forks 

appear to have failed in the past. One fork on the southwest stream passes through a small wetland, and a

potentially unstable area located below the wetland in the draw. The northeast stream has a very steep 

head wall area above one of the forks. Root strength plays a key role in this area, and all these areas 

should be included in a wider stream buffer and deleted at layout. The harvest of Unit 53 as a thinning, 

will not adversely affect slope stability on the ground around these sites. 

Unit 60: A small debris chute scar starts at the southwest corner of this unit. The soils throughout the unit 

appear naturally stable, and road drainage some distance upslope may have been part of the reason this 

area saturated and failed. The slide area should be deleted at layout and one or two rows of edge trees 

included as a buffer. 

Unit 77: A slump of 1 1⁄2 to 2 1⁄2 acres is located within the unit near the center. The area dropped about 2 

to 3 feet and moved horizontally about 6 inches to one foot. Most of the trees and stumps on the site did 

not tip. This slide appears to have resulted from concentrated the road drainage at a culvert outlet. The 

recommendation is to thin this area with a D by D prescription that retains a 50% canopy closure on the 

site and around 200 feet along each side. Logging will be implemented with a sky line system, and no 

equipment, either prebunching or skidding, should be allowed in this area. 

Unit 84: The narrow strip of land above the Fox Creek and west of Short Fox Unit 84 has very steep 

raveling soils, numerous rocky areas, and small areas of potentially unstable ground immediately above 

the creek. It should be included in a wider stream buffer and deleted at layout. 

Unit 93: An unstable area is located in the southwest corner along the creek and the old pioneer road. It 

should be included in a wider stream buffer and deleted at layout.

Unit 95: A large rocky area with pockets of potentially unstable soils or rocky unsuited areas is located 

along the southeast and south boundary. This area should be deleted at layout along the major slope 

break. This boundary will vary from about 100 feet to nearly 600 feet in elevation above Fox Creek. Also, 

a small (less than 0.05 acre) unstable area (slump or stream bank failure) lies immediately above the creek 

along the east boundary. It should be included with the buffer and deleted at layout. The harvest of Unit 

95 as a thinning, will not adversely affect slope stability on the ground below the unit boundary. 

Unit 100: Two small potentially unstable areas are present: one is associated with an old road and a 

perennial stream (Hill Creek), and the other is located near a wetland. Both areas should be deleted at 

layout with expanded riparian buffers. 

Unit 290: The rocky and potentially unstable area along the south boundary above Rd 870 should be 

deleted at layout. 

As was mentioned above, the harvest of several of the units could possibly have some indirect effect to 

slope stability from changes in ground water regimes. For this project, thinning is either recommended in 

the adjacent stands or on the unstable area to reduce stem density and enhance growth and vigor of the 

remaining leave trees in order to maintain evapotranspiration rates and avoid longer term changes to the 

local ground water regime from suppression. The removal of trees with harvest from these units could in

the short to intermediate term, reduce evapotranspiration as compared to the current condition. This could 

result in slight increases in the ground water level, which might affect slope instability down slope. 
Hwy 46 Soils and Geology Report Page 19

However, this is not considered a critical concern for three reasons: 1) These changes are anticipated to be 

within levels that are similar to natural rainfall amounts at two to ten year storm events. The potential 

intermediate impacts from thinning and a reduction in stem density will be quickly ameliorated by the 

increased growth on the leave trees; and 2) If no action occurs, suppression will result in the stands 

loosing trees or growth with a similar loss in evapotraspiration in not much longer time frames; and 3) 

Monitoring of commercial thinning harvest implemented on potentially highly unstable or actively 

unstable terrain has shown good release and not exacerbated slope instability.

Field review of previously thinned units in the past several years on both stable and unstable landtypes 

has shown no increase in either slope instability or erosion in either uplands or riparian reserves. Thinning 

within those units with potentially highly unstable or actively unstable terrain will not immediately 

promote greater slope stability. However, thinning will create healthier stands with bigger trees that have 

larger crowns and more roots. Those areas with shallow, debris chute type soil failures where rooting 

depth plays a part in slope stability, will seen improvements within a few years as crowns begin to 

respond to the increased sun light. Larger trees create more roots and tend to increase slope stability, and 

if failures do occur, they provide larger wood for down slope riparian areas. For those units with slump / 

earthflows, failure depths are below the rooting zone. However, evapotranspiration will maintain or

increase with bigger trees, and that will reduce pore water pressure in the longer term. With thinning, 

these stands will return to current levels of water usage within a few years, and this rate will be 

maintained or increased for decades into the future as the stand matures, crowns expand, and root mats 

enlarge and deepen. As mentioned previously, larger wood will also be provided to the adjacent streams. 

c) Conclusions and Rational

In summary, slope instability within the proposed thinning units that avoid potentially highly unstable or 

actively unstable terrain, is not considered likely. Potential adverse off-site effects from the harvest are 

not anticipated, and the potential for significant adverse cumulative effect is quite low. The recommended 

thinning will improve slope stability or reduce the potential for adverse off-site effects from future 

failures. For the affected units, the potentially highly unstable or actively unstable terrain will be deleted 

from the unit. No timber is proposed for harvest in any unstable terrain, except Unit 37 and 77, which are 

both semi active earthflows. Consequently, potential slope instability with proposed management in any 

unit is not considered a concern, with the design criteria mentioned previously. No additional specific 

mitigation is proposed for these units, other than the unit boundary placement, as none is needed. 

E. Transportation Development

Some units may require temporary roads to access suitable landing sites for either ground based or skyline 

yarding systems. These temporary roads are located on gentle stable side slopes in common material. 

Little or no full bench construction is required, and if needed, end haul of excess excavation will be 

required to a suitable waste area. For the most part, no active drainages are crossed. Some units are 

accessed by opening old logging roads constructed many decades ago. In most cases, use of these old 

roads will allow for drainage structure improvements and fill stabilization. Some units are accessed by 

using newer Forest Service roads that now require some additional work to maintain adequate road 

drainage and surface integrity. In summary, development of the transportation system for this sale will 

maintain slope stability, will produce little or no off site erosion, and will provide opportunity to 

rehabilitate old road courses or fills over streams.

Some specific road reconnaissance or geotechnical work conducted for this project follows:

Access to Unit 97 requires the extension of Rd 4688 for about 400 feet of new, full-bench construction on 

side slopes around 65 to 75%, to access a broad, gently sloping ridge line. The soils through this section 
Hwy 46 Soils and Geology Report Page 20

are stable, and excavation conditions would be approximatley 70% common and 30% rip. The 

recommended cut slope is 3⁄4:1. End haul of excess excavation is required, and a suitable waste area is 

located a couple miles to the east along Rd.4688 in the plantation just beyond the southwest corner of 

Unit 90. No streams, wet lands or seepage areas occur in this section of proposed new road construction. 

Unit 490 lies below FS Rd 4685 and has a large waste area at the topic of the unit. The waste area holds 

several thousand cubic yards and was built out from the road as an additional lane width or two for about 

250 to 300 feet along the road way. The field investigation indicated that no stability problems were 

evident, and the site could be used as a landing. The fill slope for the waste material is about 1 1⁄4 to 1, 

and no tension cracks were found anywhere in the mass. As a precaution, any landing development 

should be sloped to drain, and the ponding of water should be avoided. 

In Unit 140, a long road to access the unit is proposed, around a 1⁄2 mile or so. The route is well located to 

link together old skid and haul roads, essentially using previously disturbed ground for almost the full 

length. No streams, wet lands or seepage areas were noted, and the route is on stable ground. Side slopes 

range from about 10 to 40%, but very little additional cut or fill will be needed. The beginning of the 

route is included within the old clearing limits of Road 2231. The junction is such that the best access 

may be with a reverse spur, so a truck turn-around is required. An excellent site is located only 0.2 mile 

to the south at the junction of Rd 2231 and Rd 2231870 where a large developed area is already located 

as an additional spur road heads to the east at this same location. 

An opportunity to conduct road decommissioning in the area of Short Lake prompted the need to tie FS 

Rd 040 into FS Rd 045 by using Rd 059 (as signed in the field) and a short section of new construction of 

approximately 1000 feet in length. Road 059 (as signed in the field) is an existing road that is located on a 

broad flat ridge. The proposed new tie-through route drops from the end of the ridge to the west in two 

broad switchbacks. This new section is located on side slopes that range from 0 to about 20%. Grades are 

favorable at 5 to around 12%. Soil depths are greater than 10 feet so the entire route is located in common 

material. No drainages, seeps, or wet soil areas are evident along this route. Most of the length of 

proposed new route essentially follows existing old skid / haul road, and most of the route is located in an 

existing plantation. 

F. Unsuited lands

Unsuited, unregenerable landtypes, such as cliffs and rock outcrops, critical rocky areas, or wetlands and 

dry meadows were mapped as part of the field reconnaissance. These landtypes can control the location of 

unit boundaries or be found within units. Proposed units that could be affected include 2, 6, 16, 21, 38, 

42, 51, 53, 65, 75, 76, 84, 93, 280, 290, 300, 330,480, 530 and 580. These areas will be deleted from the 

proposed harvest units (as appropriate). Consequently, most of these unsuited areas will be avoided or 

deleted during unit layout. Skyline corridors running through the unsuited areas within a unit are 

acceptable to access suited portions of the unit. Trees in the unsuited area that need to be cut to maintain 

the integrity or safety of the sky line corridor will generally be left for down woody debris (unless other 

wise agreed to by Forest Service personnel). Partial suspension is the logging requirement over rocky 

areas. Full suspension is often desirable, but is not necessary. However, full suspension is required over 

wetlands, dry meadows and riparian sites.

C. CUMULATIVE EFFECTS ASSESSMENT

For the soils resource the scale of analysis for both direct / indirect effects and cumulative effects is 

almost always the “unit”, i.e. the stand polygon proposed for silvicultural treatment. The unit of measure 

for evaluating those effects is generally considered the percent of the “unit” affected. The major short-
Hwy 46 Soils and Geology Report Page 21

term impacts to soil productivity from harvest activity include displacement, compaction, nutrient loss, 

and instability. Forest-wide Standards and Guidelines FW – 081, Detrimental Soil Conditions, state that 

the total area of cumulative detrimental soil conditions should not exceed 20% of the total acreage within 

the activity area, including roads and landings. In most situations, preventing soil impacts is the most 

effective and feasible way of reducing cumulative effects and ensuring long-term soil productivity.

One of the primary objectives with this entry is to provide the opportunity to reduce the amount of 

impacted soil over the current condition. The primary previous impact to the soil resource from 

management on an area basis is compaction, and perhaps instability; the effects of which can both remain 

apparent for decades. Existing compaction levels have been documented and discussed for the applicable

units. Potential cumulative effects from displacement and nutrient loss with previous management were 

not observed to any degree in the field reconnaissance. With instability, most critical areas have been 

excluded from the respective units and not considered in the cumulative area. With possible instability 

from previous harvest in Units 5, 25, 37, 38, 42, and 77, the thinning with this entry is intended to 

maintain and improve slope stability over the long term. No additional instability is anticipated with 

management. In addition, no unit with a stability concern also has a concomitant compaction problem. 

As was stated previously, impacts are evaluated on a unit-by-unit basis and the 20% figure includes the 

effects from the various concerns. The soils design criteria are designed to limit the amount of additional 

displacement, compaction, nutrient loss, and instability. Some ground-based units will approach or 

exceed the 20% standard at the completion of all management activities. The percentage values could be 

exacerbated to a small degree by additional impacts from grapple piling and pile burning. Subsoiling is 

intended to reduce compaction sufficiently that cumulative levels will be below standards and guides.

Critical units are recommended for purchaser or post sale subsoiling. Units will be prioritized so that 

limited enhancement dollars will be expended on those units with the greatest anticipated cumulative 

effects from management. The objective is to remain below the 20% cumulative level, maintain long term 

soil productivity, and provide a level of erosion control that is consistent with State guidelines. However, 

Unit 190 may not be able to be reduced below the 20% threshold, though it will be lower. 

All prescriptions, design criteria, or soil protection measures discussed in this report are designed to meet 

or exceed the requirements outlined in the National Best Management Practices for Water Quality 

Management on National Forest System Lands, Volume 1: National Core BMP Technical Guide, USDA 

FS FS-990a, April, 2012. Prescriptions for soil protection and watershed considerations take into account 

past and predicted future land management activities. 

At this time, no single unit measure of long-term soil productivity is widely used. Information on the 

survival and growth of planted seedlings may indicate short-term changes in site productivity. However, 

the relationship of short-term changes to long-term productivity is not fully understood at present. 

Experience indicates that the potential impacts on soils are best evaluated on a site specific, project-byproject basis. The major soils concerns – displacement, compaction, nutrient loss, and instability - are 

most effectively reviewed, for both short and long-term effects, at the project level. With proper project 

implementation, as specified by my previous recommendations or those that immediately follow in the 

next section on design standards, unacceptable cumulative effects on the soils resource are not anticipated 

from any of the action alternatives (BMP W-5). Consequently, the utilization of soil protection measures 

and best management practices as defined in this report will generally preclude the need for additional 

cumulative effects analysis. Deviations from the standards and guidelines would be the primary trigger 

for a cumulative effects review, and no deviations are planned.

D. DESIGN CRITERIA / MITIGATIONS, by unit and common to all action alternatives 
Hwy 46 Soils and Geology Report Page 22

The various proposed units are located on productive soils as localized unsuited areas of rocks and cliffs 

or potentially unstable areas were generally avoided, unless otherwise listed. Recent thinning on similar 

landtypes on this and other Ranger Districts has shown that 1) By avoiding sensitive landtypes, slope 

stability has been maintained after harvest; 2) With appropriate suspension during logging, soil 

disturbance was minimal and off-site erosion was essentially non existent; and 3) With appropriate 

contract language and enforcement, excessive compaction which results from unrestricted tractor yarding 

did not occur. 

1. Soil Protection Measures 

The following table lists design criteria that would be necessary on a unit-by-unit basis. The information 

and recommendations were developed based on direction in the Forest Wide Standards and Guides 

(primarily FW-079, FW-090 and FW-179) to maintain or enhance soil productivity and stability, the field 

reconnaissance, and experience gained from extensive monitoring of similar projects. This data table 

addresses suspension requirements and duff retention objectives, as well as pertinent specific comments 

for particular units (where necessary). The second list, that immediately follows, has implementation 

measures that would also be applied to all units in any action alternative. 

NOTES for that Table follow:

a) Some stands or units (or portions thereof) that were reviewed in the field reconnaissance and 

discussed in this report and the unit summary section may not be included in any action alternative, 

or have been combined with other units. They are included to document the work that was 

accomplished. 

b) Partial means skyline logging with one end suspension and full suspension over draws and drainage 

courses. In a skyline configuration, the area within approximately 100 feet of tail trees or around 100 feet 

from landings is excluded from this requirement. Ground means a ground based system such as tractor, 

shovel or processor / forwarder. 

c) These Duff Retention objectives were specifically developed to apply to clear cut harvest prescriptions

on these particular landtypes. The percentages for partial cuts, thinnings, or underburns of unmanaged 

stands, which maintain an intact live root mat and canopy cover over most of the unit, could be less (to 

much less) and still achieve adequate soil protection. Duff retention monitoring in the last few years on 

underburns on various Districts indicates that these levels of duff retention are generally achieved, even if 

they are not specifically required. 

THE DATA MENTIONED ABOVE IS FOUND IN THE UNIT SUMMARY TABLE. BECAUSE OF 

ITS SIZE, IT IS A SEPARATE DOCUMENT. 

2. Site Specific Design Criteria -- common to all action alternatives

a) Ground-based equipment should generally operate in the dry season, usually considered from May

through October, unless otherwise restricted by other resource concerns or waived by Forest Service 

personnel, based on site specific evaluation. 

b) Where operable, harvested trees should be topped and limbed in the units in order to provide small limbs 

and needles for nutrient recycling. This objective has to be tempered with the need to reduce fuel loading 

to control potential wild fires, and to meet site specific standards for slash loadings. 
Hwy 46 Soils and Geology Report Page 23

c) Horses and ground -based equipment are usually limited to side slopes less than 30%, unless otherwise 

directed by Forest Service personnel, in order to reduce soil disturbance.

d) Ground-based skidding equipment shall stay on designated skid trails. Ground-based skid trails will be 

predesignated and preapproved before use (C6.41 and/or C6.42 (LTSR)). Existing skid roads should 

always be used before new skid road locations are approved. They should not usually exceed 15 feet in 

width, and the objective is to maintain a 10 to 12 foot width throughout the length. Where practical the 

skidder, cat, shovel or forwarder should travel on slash. Traveling on slash has been shown to reduce off 

site soil erosion or lessen soil compaction. Skid roads will generally be 100 to 200 feet apart with 

conventional line pulling operations, and 40 to 60 feet apart with processor / forwarder operations. 

e) Partial or one end suspension is required on skyline units, except at tail trees and landings. Given 

the irregular topography in some units, sections of ground lead may occur along some skyline 

roads. Generally this is acceptable, but approval usually requires a site specific, on-the-ground 

review of the area by Forest Service personnel. 

f) The reopening of temporary, unclassified roads should usually occur in the dry season, generally 

considered May through October to avoid surface erosion from exposed soil (unless directed otherwise by 

Forest Service personnel). Open roads should be storm proofed (i.e., water bars or drain dips) if they have 

to set through extended periods of wet weather. 

g) Where practical, at the completion of harvest activities, limbs and woody debris should be placed on areas 

of exposed soil to reduce the potential for off site soil erosion. 

h) Unclassified or temporary roads used outside the standard operating season, should generally be rocked, 

snow covered, or frozen to reduce the potential for erosion, unless other mitigating or extenuating 

circumstances are present. 

i) Cable corridors spacing should be set to both minimize damage to standing timber, as well as the under 

lying vegetation and soil.

j) Trees, not designated for harvest in riparian buffers that need to be cut to facilitate harvest operations, 

should be dropped into the stream if possible to aid in woody debris recruitment.

k) Avoid disturbance to the existing large down woody debris concentrations created by the initial entry in 

the managed stands as much as practical.

l) At the completion of harvest activities, spur roads, tractor skid roads or forwarder roads should be water

barred and scarified, as is necessary. Where possible, skid roads and landings should be subsoiled in 

order to reduce compaction and return the site to near original productivity. Subsoiling needs to be 

considered in light of the potential for root pruning, damage to existing regeneration, and the increased 

amount of soil disturbance. Consequently, “munching” is the preferred style of subsoiling. 

VIII. MONITORING REQUIREMENTS

As the proposed project is carried out, it will be monitored to evaluate implementation efficiency, 

prescription adequacy, and to update sale area rehabilitation needs or protection. Primary implementation 

monitoring will be conducted at the contract administration phase of the project by the Timber Sale 

Officer. The logger will be required to maintain adequate suspension during the harvest process, to 

remain on designated skid roads and landings with equipment, and to limit the number and extent of skid 
Hwy 46 Soils and Geology Report Page 24

roads utilized. In addition, a host of other contract requirements dealing with such items as erosion 

control, hazardous material use, fire restrictions, etc. will be enforced. Duff retention will be monitored as 

part of any post sale activity that may affect the soil resource, such as spot or pile burning, grapple piling, 

or broadcast burning. 

IX. CONSISTENCY WITH DIRECTION AND REGULATIONS

A. STANDARDS AND GUIDELINES

Prescriptions for soil protection, watershed considerations and riparian needs of the sub-basin take into 

account past and predicted future land management activities. The soils design criteria / mitigation

measures are designed to provide a level of protection and erosion control that is consistent with the 

standards and guidelines of the Willamette National Forest's Land and Resource Management Plan 

(1990). On site sedimentation is anticipated to be within National Forest and Oregon State Guidelines. 

All prescriptions or mitigation measures discussed in this report are designed to meet or exceed the 

requirements outlined in the National Best Management Practices for Water Quality Management on 

National Forest System Lands, Volume 1: National Core BMP Technical Guide, USDA FS FS-990a, 

April, 2012. Standard contract language should provide for sufficient erosion control measures during 

timber sale operations (BMP T-13). Revegetation of areas disturbed by harvest activities (such as 

landings, temporary roads, and equipment storage areas) is required with an appropriate seed mix (BMP 

T-14, T-15, and T-16). 

Other applicable Standards and Guides and/or Best Management Practices may exist which were not 

directly referenced in this document. Their exclusion does not indicate that they were overlooked or are 

inapplicable. As project development proceeds, appropriate constraints or mitigations may be added or 

changed in order to better meet the intent of adequate resource protection or enhancement as directed in 

the 1990 Willamette National Forest Land and Resource Management Plan and Final Environmental 

Impact Statement. 

B. IDENTIFICATION OF IRREVERSIBLE OR IRRETRIEVABLEE RESOURCES 

No irreversible and /or irretrievable use of the soils or geology resource is anticipated, beyond that which 

has been previously identified in the Willamette National Forest Land and Resource Management Plan, as 

amended. Various rock products for road maintenance and road reconstruction associated with the harvest 

and haul needs could come from several rock sources. Those recommended at this point are:

A) the major rock sources at Dead Horse (9-6-20, NW/NE) at milepost 4.52 on Rd 4696701, Dead Lily 

(9-6-26, NE/SE) at milepost 0.28 on Rd 4693630, Lower Skunk Creek on Rd 2231875 at milepost 0.76 

(within Unit 310), and Mansfield (9-7-4 NE/SE) at milepost 5.98 on Rd 4688000. With these large 

existing sources, expansion would generally be limited in extent (likely less than one acre) and confined 

to areas of brush or plantation trees. Each source could provide a variety of rock products for various 

management activities.

B) potential minor removal at small sources or for use as waste sites, such as Boulder Ridge (9-6-34, 

NW/SE) at milepost 0.05 (the end of the road) on Rd2231711, Dunlap (9-6-16, NW/NW) at milepost 

1.48 on Rd 4697000, Fox Creek at milepost 0.05 on Rd4698820, Hill (10-7-6, NE/NW) at milepost 4.29 

on Rd 2231810, Scorpion (9-7-8, NE/SW) at milepost 0.59 on Rd 4600033, Switchback (Rd 6685307 at 

milepost 0.29), an unnamed older rock source in Unit 74 that lies between Rd 4693000 and Rd 4693640 

at about milepost 0.20 on Rd 640, and an unnamed older rock source along Rd 2231853 at milepost 0.1

(adjacent to unit 220). Generally, pit activity would be limited to the existing clearing limits. 
Hwy 46 Soils and Geology Report Page 25

C) potential major new long term developments at Fire Camp (Rd 4688321 at milepost 1.05) and Leone 

(2231850 from 4.2 to 4.3). Both these sites would need NEPA clearance and pit development plans 

established. 

C. CONSULTATION WITH OTHERS

Some of the field work for the proposed units was coordinated with Rob Mickey, District logging systems 

specialist. Much of the rock resource development was coordinated with James Statezny, North Zone 

Engineer. 

X. REFERENCES CITED

Hammond, P. E., Anderson, J. L., and Manning, K. J., 1980, “Guide to the Geology of Upper Clackamas 

and North Santiam River areas, Northern Oregon Cascade Range”, in Geologic Field Trips in Western 

Oregon and Southwestern Washington: Oles, K. F., Johnson, G., and Niem, W., editors, Oregon Dept. of 

Geology and Mineral Industries, State of Oregon, Bulletin 101, pages 133-167. 

Legard, Harold A. and Meyer, LeRoy C., 1973: Willamette National Forest Soil Resource Inventory, 

Pacific Northwest Region, 167 p.

Peck, Dallas L., Griggs, Allan B., Schlicker, Herbert G., Wells, Francis G., and Dole, Hollis M., 1964, 

Geology of the Central and Northern Parts of the Western Cascade Range in Oregon, U.S. Geological 

Survey Professional Paper 449, United States Government Printing Office, Washington D. C., 56 p. 

Ricker, Karl, 1982, A Quaternary Geologic Reconnaissance of the Breitenbush Watershed, Oregon: for 

Columbia Geoscience, Portland, Oregon, and SUNEDCO, Dallas, Texas; 44 pages and appendices. 

Walker, George W. and Duncan, Robert A., 1989, Geologic Map of the Salem 1 (degree) by 2 (degree) 

Quadrangle, Western Oregon: Miscellaneous Investigations Series, U. S. Geological Survey, 1989G.

Respectfully submitted, 

DOUGLAS C. SHANK

Forest Geologist