Watershed Specialist Report For Hughes Creek Placer Project

Transcription

1 Watershed Specialist Report For Hughes Creek Placer Project Proposed Action The North Fork Ranger District of the Salmon-Challis National Forest has received a Plan of Operations from Cliff Simonsen (the operator) of Victor, MT. The plan of operations proposes excavation of test trenches and placering for gold at four sites along the south side of Hughes Creek between Gallagher Gulch and Klop Gulch. The project is anticipated to begin during the summer The project will occur on National Forest lands managed by the North Fork Ranger District, salmon-challis National Forest. Legal description is T25N., R21E. Sections 7 and 8, Boise Prime Meridian, Lemhi County, Idaho (Figure 1). Primary access to the site is via Forest Road #091 (Hughes Creek Road). A small tracked excavator or backhoe will walk in to the site from Hughes Creek Road at the beginning of operations, and walk out at the cessation of operations. The excavator or backhoe will excavate up to four test trenches. Access will require fording of Hughes Creek and overland travel on old prospecting routes. All test trenches are located between the creek and the base of the hillside. In addition to fording of Hughes Creek on two occasions by the excavator or backhoe, the operator plans to ford Hughes Creek twice each weekend once going in to the site and the other coming out with a pickup truck pulling a cargo trailer. The cargo trailer contains an ATV, wash plant, and sleeping/camping facilities. Planned duration of operations is for weekends throughout the period from July 1 through October 1, resulting in a potential of 30 crossings over the 3-month period by the operator. At each test site, a trench approximately 2 feet wide, 40 feet long, and 10 feet deep (or until groundwater is intercepted), will be excavated to bedrock perpendicular to the existing prospecting route. All operations (including placement of excavated materials) will be no closer than 10 feet from the outside edge of the road prism (that side of the road closest to Hughes Creek). Each trench will first be excavated in its entirety and excavated material will be segregated into topsoil, overburden, and potential pay gravels and placed adjacent to the trench. Approximately 29 cubic yards in volume may be excavated from each trench, anticipating 3 cubic yards of potential gold-bearing gravels in the lower five feet of the excavation that will be washed. Samples will be processed in a small wash plant with two integrated sluice boxes. The wash plant is on wheels and small enough to be pulled by an ATV. Discharged spoils from the wash plant are run back into the trench where water is allowed to filter subsurface. Waste water will not be allowed to overtop the trench. Should water in the trench fail to subside, it will be recirculated from the trench during operations rather than being pumped from Hughes Creek. Water used for processing will be pumped to the wash plant from Hughes Creek using a 1.5 discharge pump. The operator estimates the pump will use about 30 gpm. (A typical 4 hp 1.5 inch trash pump can pump up to 125 gpm.) The operator proposes to backfill and reshape the test trenches to a slightly mounded contour, anticipating settling in the trench locations, and perform other erosion control measures should they be necessary. Each trench shall be reclaimed prior to 1

2 excavating a new trench. Operations, including reclamation, should be completed during the 2011 operating season. The operator will provide a financial instrument to insure costs to complete site reclamation are available before the Plan will be approved. Trench excavation and associated operations (i.e., pumping water from Hughes Creek, campsite maintenance, fuel transfers) will be conducted described in the following section. Figure 1. Map of Hughes Creek Placer Proposal. Project Design Criteria The Forest Service developed the following project design criteria to address resource concerns. The proponent must incorporate these items into his Plan of Operations in order to receive approval. While these requirements do not make substantive changes to the proponent s plan, they are deemed reasonable and necessary measures to minimize the potential for adverse environmental impacts on surface resources managed by the Forest Service. Because the project is designed to minimize potential impacts to surface resources, no mitigation measures are required. 2

3 Hydrology Design Criteria to be Incorporated into the Operating Plan: 1. All operations (including placement of excavated materials) will be no closer than 10 feet from the outside edge of the road prism (that side of the road closest to Hughes Creek). 2. Test pits will be excavated to the design dimensions (2 feet wide, 40 feet long, and < 10 feet deep) or until groundwater is intercepted. 3. Discharge spoils from the wash plant are run back into the trench where water is allowed to filter subsurface. Waste water will not be allowed to overtop the trench. Should water in the trench fail to subside, it will be recirculated from the trench during operations. 4. Operations shall be conducted under dry conditions. Dry conditions generally exist from July 1 until October The operator will collect, remove and properly dispose of garbage at an off-forest facility at the end of each operational period (weekend). 6. A permit for water use will be applied for from the Idaho Department of Water Resources. The operator will not exceed the maximum amount allowed specified in the temporary permit of 0.74 acre feet per day. 7. Placer water will be obtained from Hughes Creek at a location reviewed and approved by the Minerals Administrator. 8. Any draft suction hoses used for water withdrawal from Hughes Creek would be equipped with a screen meeting requirements established by the National Marine Fisheries Service (Appendix A). The creek will not be dammed for water drafting. 9. In order to prevent petroleum products from entering the stream-channel from the pump at the water drafting sites or from the wash plant, they will be placed on an impermeable liner capable of containing their entire volume of fuel, oil, etc. Water in the liner, which may be contaminated with petroleum products, will be collected and disposed of at an offsite facility. 10. Refueling of equipment will occur at a location designated by the Forest Service on the project side of Hughes Creek. This location will be limited by terrain to minimize the potential for petroleum products to enter the stream, and will also minimize the frequency of equipment and vehicles fording Hughes Creek. A spill kit will be maintained at this location. 11. Excavated materials from the test trenches may become saturated with groundwater or rain, contributing silt to Hughes Creek. To prevent this, the operator will be required to install siltation controls approved by the Forest Service. 12. During active mining operations, seepage and turbidity will be visually monitored by the operator and the Forest Service. If visible turbidity is observed in Hughes Creek, mining operations will cease until they can be modified to prevent sediment delivery to the stream. 13. The operator will be required to backfill and reshape the test trenches as specified previously. The operator will be required to seed with an approved seed mix and cover 3

4 the reclaimed test trenches with straw mulch. The mulch layer will provide ground cover, reduce the potential for erosion, and promote revegetation of the disturbed area. Recommended Seed Mix Species Cultivar Application Rate Mountain Brome (Bromus marginata) Slender Wheatgrass (Elymous trachycaulus) Idaho Fescue (Festuca Idahoensis) 10.5 lb PLS/acre 7.5 lb PLS/acre 2.25 lbpls/acre PLS = pure live seed Total PLS Pounds /Acre = Should water fail to subside in a trench ready for reclamation, it will be pumped to a location approved by the Forest Service where it can slowly run out overland (such as via a hose), and filter out subsurface. 15. Each trench shall be reclaimed prior to excavating a new trench, or the end of the operating season, whichever comes first. 16. The bond for this operation must be posted prior to commencing any exploration activities. The amount of bond will be calculated to ensure full reclamation and revegetation of areas disturbed by the exploration activity. 17. All soil-disturbed sites associated with project activities will be monitored for the establishment and/or spread of noxious weeds. All new noxious weed infestations found at the project site will be treated for eradication by a licensed pesticide applicator. Weed treatment will occur during the spring following exploration. 18. A comprehensive list of mitigation measures that will be required as modifications of the operator's plan are contained in the Forest Land and Resource Management Plan (FLRMP) (IV-51 item la and Appendix C VII-C-pg. 1-14). They are the standards and guidelines for locatable minerals operations that occur on the Forest. Project Monitoring Because the Forest Plan requires monitoring of activities in riparian areas to ensure management objectives are met, in accordance Forest Service minerals regulations requiring compliance inspections, and due to concerns regarding potential effects, the interdisciplinary team developed the following monitoring requirements to minimize the project s potential to cause negative effects. 1. Forest personnel will monitor the operation and a bond calculated by the Forest Service to cover the costs of the required reclamation will be held to ensure that the project is completed as designed and until all reclamation is satisfactorily completed. 2. Operations may be suspended and/or changed if the Forest Service administrator determines that they are noncompliant with this decision, the approved Plan of Operations, applicable laws or regulations, or that resource conditions have changed. Operations may resume after compliance items have been resolved between the Forest Service, the operator, and appropriate regulatory agencies. 4

5 3. Forest personnel will inspect the project area for invasion of noxious weeds. Final release of the re-vegetation portion of the reclamation bond will be contingent upon satisfactory treatment of weeds introduced or spread by the operations. Current Conditions A field review of the placer test pits was conducted in the summer of 2010 to evaluate potential effects of the proposed placer mining operation. The proposed project is located in the valley bottom of Hughes Creek adjacent to areas that have been placer mined in the past. The four test pits are located on a road prism adjacent to the active floodplain of the Hughes Creek. Past mining activity in the project vicinity includes historic pits, ponds, ditches and hydraulic mining of sideslopes (Figure 2). Figure 2. Historic hydraulic mining in the vicinity of the proposed project. Each test pit site was looked at in the field to evaluate the potential for effects to wetlands and proximity to surface water. All test pits are located in sites that are not considered wetlands or waters of the US but are well within the Riparian Habitat Conservation Area (RHCA) as defined in PacFish as 300 feet on either side of a fish bearing stream. Vegetation in these upland sites is a transition zone characterized by a Douglas Fir Idaho Fescue community on the slope transitioning to an Alder/Willow Forb community on the floodplain. All test pits are located within 300 feet from the Hughes Creek. Test pit #1 is the closest at approximately 36 feet from Hughes Creek, Pit #2 is approximately 120 feet, Pit # 3 is approximately 75 feet, and finally test Pit # 4 is approximately 48 feet from Hughes Creek. All 5

6 pits are located at the slope break adjacent to a heavily vegetated riparian zone. Design features listed above will prevent any overland flow of water or sediment. Water Quality The Clean Water Act (CWA) requires that the states and tribes restore and maintain the chemical, physical and biological integrity of the nation s waters. As mandated by the CWA the State of Idaho is required to conduct a comprehensive analysis of Idaho s water bodies every two years to determine whether they meet state water quality standards and support beneficial uses or if additional pollution control measures are needed. This analysis is summarized in an Integrated Water Quality Monitoring and Assessment Report that is submitted to the U.S. Environmental Protection Agency (EPA) for approval. Current direction for water quality management in the Middle Salmon Panther Subwatershed and Hughes Creek is guided by the 2008 Integrated Water Quality Monitoring and Assessment Report (Integrated Report) (IDEQ, 2009) and the Land Resource Management Plan for the Challis National Forest (USDA, 1987). The 2008 Integrated Report has determined that Hughes Creek from source to the mouth is fully supporting beneficial uses. Beneficial uses in this watershed include cold water aquatic life, salmonid spawning, and secondary contact recreation. Water Quality assessments were completed by the Idaho Department of Environmental Quality (IDEQ) on the Yankee Fork to determine that the beneficial uses were fully supported. The data collected by IDEQ is available on their website (deq.idaho.gov). The Forest Service has a monitoring station on the Hughes Creek to assess the long-term trends for sediment and streambank stability. The Hughes Creek 1A is located approximately one half mile downstream from the project area. Parameters collected at this station include fine sediment levels at depth and streambank stability. Data has been collected at this station since 1993 and the last ten years of data is displayed in Table 1. With the exception of 2004 the level of fine sediment at this station has met the Salmon Forest Plan standard for fine sediment at depth of less than 20 percent for an anadromous stream (Table 1). Depth fines trend for the Hughes Creek 1A site is improving with a downward trend since 1993 (Figure 3). Streambank stability at this station has improved since 1995 and has met the Pacfish standard of 80% or higher bank stability since 2003 (Figure 4). Year Percent Fine Sediment Percent Streambank Stability Table 1. Hughes Creek Station 1A. Water quality data for the past ten years. 6

7 35.0 Hughes Creek 1A Depth Fines Trend Mean Percent Fines <.25" at Depth Figure 3. Hughes Creek depth fines trend. Percent Stable Banks Hughes Creek 1A Bank Stability Trend Figure 4. Hughes Creek 1A depth fines trend. 7

8 Environmental Effects Direct and Indirect Effects The proposed placer test pits are located on an existing roadbed in a flat reasonably controlled environment (Figure 5). The design features listed above dictate allowable water levels in the test pits and establish work stop triggers that provide reasonable assurance that overland flow will not occur as a result of the proposed operations. No sediment delivery to Hughes Creek is anticipated from the proposed mining operation. Surface disturbance will be minimal (less than 1 acres) and reclamation will be kept current during the operating season such that only one pit test area will be worked at a time and reclamation completed at that site prior to moving to the next site. Figure 5. Test Pit #1 typical view of pit sites. During excavation of the test pit sites topsoil and organic material will be stockpiled separately from the subsoil. Stockpiled material will be contained with silt fence, straw wattles, or certified weed free straw bales to capture sediment in the event of a runoff precipitation event. Test pit sites will be filled, recontoured, dressed with topsoil and organic material, seeded and mulched to restore native vegetation in the disturbed areas. 8

9 To reduce the potential for any adverse water quality impacts from equipment fueling several design criteria have been incorporated into the proposed project. The criteria include secondary containment of pumps and fuel for mining operations near surface water. Petroleum absorbent pads shall be utilized under equipment during servicing. Any contaminated materials generated by the operator s activities will be removed and properly disposed of off-forest. In areas of past placer mining activities there is a potential to encounter mercury that is still present in the floodplain and/or groundwater from past mining activity. The operator will be required to monitor his excavations for the presence of visible mercury. If visible mercury is detected, the operation will immediately cease and the operator will be required to notify the District Ranger or the Forest Service Minerals Administrator. Operations may be allowed to resume following consultation with the Idaho Department of Environmental Quality and implementation of any mitigation stipulated by the regulatory agencies. Stream crossing of Hughes creek to access the site will limited in time and number of crossings. During the three month operational period from July 1 through October 1, 30 crossings will be allowed. The Hughes Creek ford at this location has shallow approaches and is well armored (Figure 6). No adverse effects to the channel shape or function are anticipated from the proposed crossings. Figure 6. Hughes Creek ford on access road. 9

10 Cumulative Effects The cumulative effects analysis area for this project is the Hughes Creek Subwatershed ( ). Land uses in the Hughes Creek subwatershed include historic mining, Present and historic timber harvest and associated road work, recreation and private land activities. Historic hydraulic and placer mining has disturbed stream channels and riparian areas along Hughes Creek and many of its tributaries. Historic mining has resulted in channel alteration and floodplain modification. Altered topography and coarsening of hillslope materials is evident on slopes adjacent to Hughes Creek and its tributaries. Dispersed recreation in the area includes camping, hunting, fishing and sightseeing. An example of a typical dispersed campsite is the camp area identified in this proposal. Other activities in the area include maintenance of Forest roads and trails, bridges, and culverts. The cumulative effects of past and ongoing projects on hydrologic and riparian function and water quality within the Hughes Creek area are reflected in the current conditions described above. All of the projects, actions and activities that have occurred in the area to date have, or have had the potential to cumulatively shape or influence the resource as it exists today. The degree of influence is a function of the nature, location and magnitude of those past and ongoing activities. Summary of Effects No adverse impacts to water quality are anticipated if the Project Design Criteria described above are implemented during the excavation, testing and reclamation of the proposed test pits. Revegetation of disturbed areas will be accomplished by backfilling the pits, recontouring the disturbed area, topsoil replacement, seeding with a native species mix and mulching with certified weed-free straw. No adverse impacts to wetlands or floodplains are expected from the proposed mining operation. David Deschaine March 17, 2011 Hydrologist References IDEQ, Principles and Policies for the 2008 Integrated (303(d)/305(b)) Report. Idaho Department of Environmental Quality. May, USDA, Land Resource Management Plan for the salmon National Forest. June,