North Fork Blackfoot Trail Bridges Project

Transcription

1 North Fork Blackfoot Trail Bridges Project Soils Report Prepared by: Claire Campbell Lolo National Forest Soil Scientist for: Seeley Lake Ranger District Lolo National Forest June 1, 2017

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3 Table of Contents Introduction... 2 Relevant Laws, Regulations, and Policy... 2 Regulatory Framework... Error! Bookmark not defined. Topics and Issues Addressed in This Analysis... 4 Issues... 4 Other Resource Concerns... 4 Resource Indicators and Measures... 4 Methodology... 4 Spatial Analysis... 4 Spatial and Temporal Context for Effects Analysis... 4 Affected Environment... 5 Existing Condition... Error! Bookmark not defined. Environmental Consequences... 6 Alternative A No Action... 6 Alternative B Proposed Action... 7 Summary... 7 Compliance with LRMP and Other Relevant Laws, Regulations, Policies and Plans... 7 Resource Protection Measures... 1 References Cited

4 Introduction This report describes the guiding soils policy, existing soils conditions, and discloses the potential soil issues associated with the North Fork Blackfoot Trail Bridges project on the Seeley Lake Ranger District. The project focuses on the need to replace the existing trail bridges. Summary Replacement and construction of the North Fork Blackfoot Trail Bridges along the Hobnail Tom Trail #32 has no anticipated detrimental impact to soils within the project area. The project fully complies with all soils goals and objectives as defined in the National Forest Management Act direction, USFS Region 1 Soil Quality Standards (R1 SQS), the Lolo National Forest Plan, and other guiding regulations (Table Soils 1). Below is a short summary: 1. Authorized transportation systems, including roads and trails, are not considered part of the productive land base (36 CFR 212.1). Therefore, these features are excluded from further soil analysis, and the goals and objectives towards soil productivity do not apply within these transportation corridors. Areas adjacent to the bridge sites are still subject to soils policies associated with the Lolo Forest Plan and National Forest Management Act, which state that all land management activities must not significantly impair soil productivity. 2. The proposed action includes design criteria and site-specific resource protection measures (RPMs) that would allow for soil development, forest floor rehabilitation, and increasing soil nutrient cycling over time. Both alternatives meet the necessary regulatory guidance. While soil disturbance is never completely avoidable during ground-disturbing land management activities, the impacts to soils are not anticipated to be detrimental to soil resiliency. 3. The Soil Scientist would continue to be involved with activities within the project area including initial planning, project design, layout, contract preparation, and project implementation, or as needed to fulfill soil resource objectives and ensure minimized soil disturbance associated with the project area. Relevant Laws, Regulations, and Policy The soils resource on National Forest System (NFS) land is regulated in order to sustain soil productivity for resilient vegetation and to provide for other ecosystem functions, such as retaining soil moisture, moderating nutrient cycling, and conserving soils against land loss. In particular, the Lolo National Forest Land and Resource Management Plan (USDA Forest Service 1986) as well as other national and regional guidance provide specific direction on the management of the soils resource during land management activities. Authorized transportation systems, including roads and trails, are not considered part of the productive land base (36 CFR 212.1). Thus, these features are excluded from further productivity analysis, and detrimental soil disturbance standards do not apply. While detrimental soil disturbance is not considered in administrative sites, the Lolo Forest Plan and NFMA still require soils to be left on a trend towards soil recovery and that soil, slope, or other watershed conditions are not irreversibly damaged following project implementation (NFMA 16 U.S.C C). Desired Conditions Guiding soils policy on the Lolo National Forest (NF) aims to leave site conditions with soils that are resilient to land management activities and sustain long-term soil productivity. 2

5 Table Soil 1. Regulatory Guidance for NEPA Analysis on Soil Resources Regulation National Forest Management Act (16 U.S.C. 1604) (1976) Lolo National Forest Plan (1986) 2550 Watershed and Air Management Manual (FSM) (November 2010) Region 1 FSM Soil Supplement (effective 11/12/99) Legal Guidance The Renewable Resource program (C) recognize[s] the fundamental need to protect and where appropriate, improve the quality of soil, water, and air resources and states that "(i) soil, slope, or other watershed conditions will not be irreversibly damaged from forest management activities. Chapter II:12-13 Forest-wide Management Direction was established to protect the watersheds and forest soils. This direction is accomplished through the application of best management practices to (#15) assure water quality meets or exceeds Federal and State standards, (#16) a soil review of project feasibility, (#17) a watershed cumulative effects analysis, (#18) and design or modification of management actions to maintain land productivity. Soils management objectives include: (1) Manage resource uses and soil resources on National Forest System lands to sustain ecological processes and function so that desired ecosystem services are provided in perpetuity (page 4); (2) Soil policy states that the use of soil properties to assess the condition and potential effects on soils, when planning and implementing project activities is to occur and include soil function and processes in addition to soil disturbance (page 5). Objectives include managing NFS lands without permanent impairment of land productivity and to maintain or improve soil quality. Region 1 SQSs are based on the use of six physical and one biological attribute to assess current soil quality and project effects (compaction, rutting, displacement, severely-burned soils, surface erosion, soil mass movement, and organic matter (the biological attribute)). These attributes are easy to measure in the field and when interpreted by journey-level soil scientist provide reasonable assessment of soil quality (Powers 2002). Specifically on developed administrative sites, including National Forest Transportation systems, Soil Quality Detrimental Soil Disturbance standards do not apply. Region 1 FSH Watershed Conservation Practices Handbook (FSM , R1/R4 Amendment No 1 (05/88) and Forest Service National BMPs (2012) Provides direction for the implementation of Watershed Conservation Practices or Best Management Practices (BMPs). Implementation of BMPs minimizes effects of management activities on soil and water resources and protects water-related beneficial uses. Best Management Practices are designed to assure compliance with the Clean Water Act (Sections 208 and 319 Non-point Source Pollution) and State of Montana Water Quality Standards (MOU National Forest and State of Montana, Jan 30, 1987). 3

6 Topics and Issues Addressed Issues While Regional policy for soil quality standards do not apply to the bridges and the trail system, adjacent construction staging areas are subject to some resource concerns including: 1. Soil erosion associated with construction activities along streambanks and where bare soil conditions arise. 2. Soil productivity loss associated with localized soil compaction and displacement within the construction area. Potential areas of concern include construction staging areas, burn piles, workcrew campsites, incidental social trails, impacts from significant livestock use, and adjacent to the bridge abutments where soils may be impacted. Maintaining site productivity is necessary to comply with NFMA and the Lolo Forest Plan. Other Resource Concerns No resource concerns related to soils were brought forward during public scoping. Resource Indicators and Measures Methodology Data for the North Fork Blackfoot Trail Bridges project was derived from a combination of spatial analysis and a field site visit to analyze the effects to soils adjacent to the bridge construction. Field soil quality assessments would be performed by the soil scientist during the spring of 2017 prior to project implementation. Spatial Analysis Spatial analysis was used to support field survey and estimate erosion hazard and recovery potential based on Forest Service corporate databases, in particular, the Lolo NF Landscape System Inventory (LSI, 1989). This document provides information on forest landtypes, and provides interpretations to the watershed impacts of activities associated with these landtypes, including soil erosion potential, mass failure risk, and impacts to soil productivity. Spatial and Temporal Context for Effects Analysis Soil productivity is a site-specific characteristic that is limited to the geographic area were soils are impacted by land management activities (USDA Forest Service 1999:R1 SQS). For the North Fork Blackfoot Trail Bridges project, areas adjacent to the bridge locations were analyzed for soil impacts, including possible construction staging areas and campsites for the work crew. A larger geographic area such as a watershed or project area is not considered an appropriate geographic area for soil cumulative effects analysis. Assessment of soil quality within a larger area (such as a watershed) which includes both activity and non-activity areas can mask or dilute site-specific effects. In contrast to soil productivity, processes such as erosion regimes and hydrologic functions occur at a watershed scale and have been analyzed as such in the Fisheries or Hydrology Specialist s Report. Soil disturbance is temporally bound by the time for soil to recover from ground-based disturbances which impact soil productivity. Non-mechanized soil disturbance recovers after short-term intervals as native vegetation re-establishes in the area. In this case, soil recovery would occur in a short-term time interval (less than 10 years). 4

7 Long-term soil impacts include impairment to soils that is expected to last greater than 10 years. In this case, no long-term impacts are expected to soils in the project area. Direct and Indirect Effects Boundaries The spatial boundaries for analyzing the direct and indirect effects to soils are the site-specific work sites where ground disturbance would occur, in this case, the construction staging area, areas adjacent to bridge abutments, campsites, and incidental social trails. The temporal boundaries for analyzing the direct and indirect effects are based on the time associated with soil recovery with respect to soil stability and productivity. In this case, soil stability and soil productivity are tied to revegetation of ground cover vegetation which stabilizes soil through root establishment and promotes forest floor rehabilitation with organic matter production and nutrient cycling. Cumulative Effects Boundaries For the soils resource, cumulative effects which overlap in time and space are considered within the project area, where there are spatial overlaps from forest management activities. No past land management actions, other than the construction of the original bridges, were identified in the Scapegoat Wilderness area, therefore soil impacts were not analyzed, and no current, or reasonably foreseeable impacts to soils are anticipated beyond the scope of the proposed action. Affected Environment Soils within the project area are variable based on location and land type. The Lolo NF LSI shows that soils in this area include stream bottoms (10UC), stream terraces (13UB), and stream break-lands (61QA). Adjacent to the bridge construction area, glacial valley trains (46OA) and glacial mountain slopes (48QA) may also be impacted by project staging, campsites, or other activities. Risks to soil productivity and stability are summarized by land types in Table Soil 1. In designated Wilderness areas, impacts to soils are limited to non-motorized uses, including human and stock foot traffic, fire suppression activities, and in this case, trail and bridge construction and maintenance. Hobnail Tom Trail #32 is part of the Lolo NF transportation system, and therefore, Region 1 Soil Quality Standards for site productivity do not apply (Region 1 FSM Soil Supplement , 1999). Adjacent to the trail system, soils are not disturbed. Soil stability concerns in stream bottoms, stream terraces, and stream break-lands are closely tied to soil erosion from normal flow or elevated flow and flooding events, which can cause stream bank scour and failure. Currently, the bridges on the Hobnail Tom Trail are encroaching on bankfull width of the North Fork of the Blackfoot River, resulting in faster water flows and more risk to soil instability associated with bank scouring. By widening the bridge abutments outside of the Q2 flood level, the project would mitigate this risk and allow soil revegetation to stabilize the river banks. 5

8 Table Soil 1. North Fork Blackfoot Trail Bridges project land types and associated risks and limitations Land Types in Project Area Landform Description (LSI Map Unit) Soil Productivity: Risks and Limitations Soil Stability: Risks and Limitations Bridge Sites Land types associated with the specific bridge locations, including abutments and approaches Stream bottoms, 10UC, 13UB, Loess and Ash influenced soils (all): Fine textured soils with rutting and Surface Erodibility Potential: Low- Moderate terraces, 61QD compaction risk. These soils are Landslide Potential and Geologic and inherently poor in nutrient capital; soil hazard: Low-Moderate dissected fertility is held in the upper portion of the stream breaklands soil profile influenced by root, vegetation, and biologic activity. Displacement and Compaction Risk: Moderate-High Low effective soil moisture (10UC): Soils are shallow and prone to drought conditions. Wind-throw erosion risk (10UC): based on shallow rooting depth because of water table. Potential Nutrient Concerns (13UB): Low organic matter in surface soils, nutrient availability becomes problematic when surface soil erosion occurs. Adjacent Areas Land types that may be impacted by construction staging, campsites, etc. Glacial valley train 46OA None applicable Surface Erodibility Potential: Moderate Landslide Potential and Geologic Hazard: Low Glaciated mountain slopes Displacement and Compaction Risk: Moderate 48QA None applicable Surface Erodibility Potential: Moderate Landslide Potential and Geologic Hazard: Moderate Displacement and Compaction Risk: Low-Moderate Environmental Consequences Alternative A No Action Under the Alternative A, there are no impacts to the soils resource. The project area will continue to receive light foot traffic and recreational uses from stock users and hikers, including dispersed camping, stock grazing and watering, and other recreational activities. 6

9 Alternative B Proposed Action Direct and Indirect Effects The bridge construction project would have limited impact to the soils resource, predominantly in areas immediately adjacent to the bridge locations, where construction activities and staging would occur. In these areas, incidental social trails from work crews could lead to localized soil compaction, vegetative cover loss, and an increased risk of soil erosion during project implementation. Potential project designs may allow for old bridge materials to be burned on site. In these instances, burn piles would be limited in size and site-specific RPMs would be followed to return soils to the productive land base by reintroducing native forest floor materials on burned locations. All impacts associated with this project are considered to be short-term, with no lasting, irreversible impacts to the productive soil base. No indirect impacts to the soils resource are expected from this project. Cumulative Effects Cumulative effects for the soils resource must overlap in time and space and cause a lasting impact to soil conditions. Past, on-going, and reasonably foreseeable activities in the project area include continued recreational uses by both hikers and stock animals, which will result in incidental soil productivity impacts, particularly soil compaction and forest floor disturbance associated with accessing water, dispersed camping, and stock grazing. These impacts are short-term impacts to the soils resource and are not considered irreversible or irretrievable impacts to soil recovery. Summary The North Fork Blackfoot Trail Bridges project would have no anticipated impacts to the soils resource. Alternative A would have no impact to soils, as no additional activities would occur. Alternative B would have no significant effect, as soil RPMs and design criteria would provide for recovery of soil productivity and stability. The Soil Scientist would continue to be available throughout project design and implementation to fulfill soil resource objectives for the project. Compliance with LRMP and Other Relevant Laws, Regulations, Policies and Plans The North Fork Blackfoot Trail Bridges project is consistent with the Lolo NF Forest Plan, NFMA, and all soil policy. The proposed project is consistent with the goals, objectives, and standards for soil resources set forth in the Lolo Forest Plan because project design criteria and RMPs have been included to protect soil resources and limit the disturbance footprint, and landscapes with sensitive soils have been identified and protected. The Soil Scientist has been involved in project planning and would be involved with the project through implementation by coordinating with other team members to ensure the maintenance and enhancement of soil resources. The National Forest Management Act (NFMA) requires that all lands be managed to ensure maintenance of long-term soil productivity, hydrologic function, and ecosystem health. All activities proposed are consistent with this direction; proposed activities would not result in irreversible damage to the soil resource. 7

10 Resource Protection Measures for Soils The resource protection measures below are designed to ensure that there are no detrimental impacts to the soils resource associated with the proposed action. 1. Slash will be used to stabilize bare soils and streambanks during and following project implementation. Slash of mixed sizes (at least 50% < 6 inches diameter) would be placed over approximately 65 70% of the bare soil and streambanks to a depth of approximately 2 3 inches where available (approximately t/a). Most slash would be in direct contract with the soil surface. 2. Native duff materials will be gathered from adjacent undisturbed areas and spread in locations with bare soil resulting from project activities. Remove forest duff and litter (surface soils) from an area approximately 2 feet X 2 feet in areal extent and 3-4 inches in depth from an adjacent, undisturbed site. Spread collected duff material on the surface of disturbed areas. Duff can be removed from any adjacent area, leave approximately 10 feet between removal areas to reduce disturbance to adjacent sites. Collected duff material should be spread in a similar volume to seeding protocols; one duff collection should be sufficient to treat approximately 1/8 acre of land. Following duff placement, slash (see Soil-1) should be placed on these areas to discourage social trails and provide shading and erosion control for the native seed bed. 3. Burn piles will be located in areas of disturbed soil if possible; size of pile should be limited to existing disturbance footprint. If burn pile is located in an undisturbed area, piles would be limited in size to 10 x 10 feet. Following burning, native duff materials from adjacent areas should be incorporated (raked) into the burn pile (see Soil-2). Slash (following guidance in Soil-1) should then be placed to cover the burn pile to provide shading, erosion control, and discourage re-use of the burned areas. 4. Trails established during construction that are not part of the trail system would be decommissioned after use. Decommissioning will include: a. Trail would be decompacted to a depth of at least 6 inches by hand. Decompaction techniques should avoid mixing topsoil (4-6 inches in depth) with infertile subsoil below (> 6 inches). b. Native duff would be placed over decompacted area to re-introduce soil microbial populations and native seed (see Soil-2). c. Slash would be placed over decommissioned trails to provide shading and prevent erosion (see Soil-1). 1

11 References Cited Carlson, T and Hadlow, A Lolo National Forest Plan Soil Monitoring and Evaluation Report for U.S. Department of Agriculture, Forest Service. Lolo National Forest, Missoula, MT. USDA Forest Service Lolo National Forest Plan. U.S. Department of Agriculture, Forest Service, Lolo National Forest. Missoula, MT. 416p. USDA Forest Service Lolo National Forest Land Systems Inventory. Sasich, J. and K. Lamotte- Hagen, edits. Missoula, MT. USDA Forest Service FSM 2500 R1 Supplement , Chapter 2550 Soil Management. 6p. USDA Forest Service, Region FSH R1/R4 Amendment No 1. Region 1 Soil and Water Conservation Practices Lolo National Forest Best Management Practices Effectiveness Monitoring Report. 117p. [accessed April 5, 2017]. 1