Attachment_2a_El_Capitan_NTCRA_Work_Plan_(rev_Figure_9_and_updates_6-30-23)_0002.pdf

4015 13th Avenue W, Seattle, WA 98119 ▪ Billing: 2212 Queen Anne Ave N, #602, Seattle, WA 98109 Office (206) 691 0476 ▪ Fax (206) 675 0650 www.kane-environmental.com

Final - Non Time-Critical Removal Action Work Plan

El Capitan Former Waste Disposal Area Yosemite National Park, California

Prepared For:

National Park Service, PWR - SF/SEA MABO 333 Bush Street Suite 500 San Francisco CA 94104

June 30, 2023

Project Number: 49723-2.3

Prepared By:

Kane Environmental, Inc.

4015 13th Avenue West Seattle, WA 98119

Stephen Dailey John R. Kane, L.H.G.

Professional Engineer Principal

Non Time-Critical Removal Action Work Plan i

TABLE OF CONTENTS

ACRONYMS AND ABBREVIATIONS .............................................................................................................. v

1.0 INTRODUCTION

2.0 PURPOSE

3.0 SITE CONDITIONS & BACKGROUND

3.1 Site Description (2.1)

3.2 Operational History (2.2)

3.2.1 Yosemite National Park (2.2.1)

3.2.2 Site (2.2.2)

3.3 Previous Cleanup Actions (2.10)

3.4 Waste Characteristics (2.4)

3.5 Historically/Culturally Significant Features (2.3)

3.6 Current/Future Land Uses (2.13)

4.0 PHYSICAL AND ENVIRONMENTAL SETTING

4.1 Site Topography and Features (2.1)

4.2 Climate (2.7)

4.3 Regional and Local Geology (2.5.1)

4.4 Surface Water Hydrology (2.6)

4.5 Hydrogeology (2.5.2)

4.5.1 Groundwater Use (2.5.2)

4.6 Ecological Setting (2.8)

4.6.1 Habitat (2.8.1)

4.6.2 Species of Special Concern (2.8.2)

4.7 Sensitive Environments (2.9)

4.8 Site Contaminants (2.11)

4.8.1 Media/Contaminants of Concern (2.11.2)

4.8.2 Sources of Contamination (2.14.1)

4.8.3 Summary of Investigations (2.11.1)

4.8.4 Data Summary (2.11.3)

4.8.5 Human Receptors of Concern

5.0 REGULATORY FRAMEWORK

6.0 REMOVAL ACTION

6.1 Conceptual Site Model (2.14)

6.1.1 Sources of Contamination (2.14.1)

6.1.1 Transport in the Environment (2.14.2)

6.1.3 Populations of Concern (2.14.3)

6.1.4 Exposure Pathways of Concern (2.14.4)

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6.1.5 Human Health Risk Assessment Conclusions (3.1.7)

6.1.6 Ecological Risk Assessment Conclusions (3.2.5)

6.2 Removal Action Objectives (5.1)

6.3 Removal Action Levels (5.3)

6.4 Areas to Be Addressed by Removal Action

6.4.1 Contaminated Soil and Associated Waste (5.4.1)

6.4.2 Groundwater (5.4.2)

6.4.3 Sediment Porewater (5.4.3)

6.5 Overview of Removal Action (6.5)

7.0 APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS

8.0 WASTE CHARACTERIZATION AND DISPOSAL PLAN

8.1 Waste Characterization and Segregation Operations

8.2 Waste Transportation and Disposal

9.0 INSTITUTIONAL CONTROL PLAN

10.0 REMOVAL PLAN IMPLEMENTATION

10.1 Activities Prior to Mobilization

10.1.1 Scheduling

10.1.2 Resources Protection Briefing

10.1.3 Health and Safety Plan and Accident Prevention Plans

10.1.4 Stormwater Pollution Prevention Plan

10.2 Site Preparation and Security Measures

10.2.1 Site Facilities

10.2.2 Access Road Preparation

10.2.3 Delineation of Excavation Areas

10.2.4 Utility Clearance

10.2.5 Baseline Groundwater Sampling

10.2.6 Monitoring Well Abandonment

10.2.7 Security Measures

10.2.8 Contaminant Control

10.2.9 Permits and Plans

10.3 Field Documentation

10.3.1 Field Logbooks

10.3.2 Chain-of-Custody Records

10.3.3 Photographs

10.4 Excavation

10.4.1 Shoring

10.4.2 Excavation Plan

10.4.3 Temporary Storage Operations

10.4.4 Inspection of Equipment

10.4.5 Decontamination Area

10.5 Dust Control

10.5.1 Dust Control Measures

10.5.2 Dust Monitoring

10.6 Confirmation Sampling

10.7 Soil Stockpile Characterization

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10.8 Transportation Plan for Offsite Disposal

10.8.1 Soil Loading

10.8.2 Destination of Soil

10.8.3 Soil Transportation Mode

10.9 Backfill and Site Restoration

Table 10.2 Estimated Backfill Volumes

10.9 Post-Construction Activity

10.10 In Situ Groundwater Treatment

10.10.1 Pre-Design Investigation

10.10.2 Monitoring Well Installation

10.10.3 Addition of Groundwater Amendments

10.10.4 Monitored Natural Attenuation

10.11 Removal Action Closure Report

10.12 Other Deliverables

11.0 REFERENCES

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FIGURES

Figure 1 Vicinity Map Figure 2 Access Routes Figure 3 Site Plan Figure 4 2015 & 2016 Geophysical Survey Areas and Results Figure 5 2016 & 2017 Site Investigation Sample Locations Figure 6 Excavation Plan Figure 7 Conceptual Site Model Figure 8 Temporary Erosion and Sedimentation Control Plan Figure 9 Conceptual New Monitoring Well Locations Figure 10 Typical Excavation Cross-Section

TABLES

Table 6.1 Removal Action Levels Table 8.1 Estimated Excavation Areas and Volumes Table 10.1 Dust Exposure Level Comparison Table 10.2 Estimated Backfill Volumes

APPENDICES

Appendix A Chemical-Specific, Location-Specific, and Action-Specific Applicable or Relevant and Appropriate Requirements

Appendix B Transportation Plan Appendix C Sampling and Analysis Plan v

ACRONYMS AND ABBREVIATIONS

amsl Above Mean Sea Level ARARs Applicable or Relevant and Appropriate Requirements bcy Bank Cubic Yard(s) BERA Baseline Ecological Risk Assessment bgs Below Ground Surface BMP Best Management Practice BTOC Below Top of Casing Cal-EPA California Environmental Protection Agency Cal-OSHA California Occupational Safety and Health Administration Caltrans California Department of Transportation CCR Code of California Regulations CERCLA Comprehensive Environmental Response, Compensation, and Liability Act CFR Code of Federal Regulations COCs Contaminants of Concern COECs Contaminants of Ecological Concern CWC California Water Code cy Cubic Yard(s) DTSC California Department of Toxic Substances Control DU Decision Unit EE/CA Engineering Evaluation/Cost Analysis ESV Ecological Screening Value FIR Facility Investigation Report HASP Health and Safety Plan HAZWOPER Hazardous Waste Operations and Emergency Response HHRA Human Health Risk Assessment HQ Hazard Quotient ICIAP Institutional Control Implementation and Assurance Plan LOAEL Lowest-observed-adverse-effect-level

MNA Monitored Natural Attenuation MRP Final Merced River Final Comprehensive Management Plan and Environmental

Impact Statement NCP National Contingency Plan NOAEL No-observed-adverse-effect-level NPDES National Pollutant Discharge Elimination System NPS National Park Service NPS-SF National Park Service, San Francisco Regional Office NTCRAWP Non Time-Critical Removal Action Work Plan OSHA Occupational Safety and Health Administration PAHs Polynuclear Aromatic Hydrocarbons PbB Concentration of Lead in Blood PCP Pentachlorophenol vi

PFAS Per- and Polyfluoroalkyl Substances PDI Pre-design investigation RA Removal Action RAO Removal Action Objective RCRA Resource Conservation and Recovery ACT RG Removal Goal SDS Safety Data Sheet SLERA Screening Level Ecological Risk Assessment SVOCs Semi-Volatile Organic Compounds SWPPP Stormwater Pollution Prevention Plan TEQ Toxic Equivalency Quotient TPH Total Petroleum Hydrocarbons YOSE Yosemite National Park ZVI Zero-valent Iron

1.0 INTRODUCTION

The National Park Service (NPS) has contracted Kane Environmental, Inc, (Kane) to prepare a Non-Time

Critical Removal Action Work Plan (NTCRAWP) at the El Capitan Former Waste Disposal Area (the “Site”), located within Yosemite National Park, California (Park), under order number 140P8521F0019.

2.0 PURPOSE

The purpose of the work described in this NTCRAWP is to remove contaminated soils and debris that pose a threat to human health and the environment. Removal of contaminated soils and debris will also facilitate remediation of groundwater contamination.

3.0 SITE CONDITIONS & BACKGROUND

Information in this section is derived from the Engineering Evaluation/Cost Analysis Report (EE/CA), Section 2 (CDM 2020). Subsection headings indicate the EE/CA section from which text in that subsection is derived. In some cases, text in this section is copied verbatim from the EE/CA; in other cases, text in this section is condensed from the EE/CA, and/or additional clarifying information has been added.

3.1 Site Description (2.1)

The Site is located on the western side of the Sierra Nevada Range in central California, in Yosemite Valley approximately 2.7 miles west of Yosemite Village along Northside Drive. It occupies roughly 2.5 acres on a stream terrace bounded to the north by a yellow pine forest and to the south by the Merced River (Figure

1). The Site is on the south side of Northside Drive and east of the El Capitan Bridge. Access routes to the site are shown on Figure 2.

The Site is located at latitude 37.72399N and longitude 119.62239W, approximately 3,950 feet above mean sea level. It is in Township 2 South, Range 21 East, Section 35 of the Mount Diablo Meridian. A site plan is shown on Figure 3. The meadow present on the western portion of the site is known as Slaughterhouse

Meadow, noted on Figure 3.

The Site is located approximately 2,000 feet southeast of the base of El Capitan, a granite monolith that rises more than 3,500 feet above the valley floor and is a popular recreational area for experienced rock climbers.

3.2 Operational History (2.2)

3.2.1 Yosemite National Park (2.2.1)

The Yosemite Valley was historically inhabited by the Ahwahneechee native people before the arrival of

European Americans in the mid-1800s; it began receiving visitors in the 1850s. The Yosemite Valley was granted to the State of California in 1864 because of public appeal for conservation. The Park was established in 1890, and federal ownership of the Park began in the same year as the Park’s establishment.

When the Yosemite Valley was added to the Park in 1906, ownership of Yosemite Valley transferred from the state to the federal government.

3.2.2 Site (2.2.2)

With the extension of roads into Yosemite in 1874, the Park experienced increased visitation and development. Hotels and hotel-camp style establishments were built into the early 1900s to accommodate increasingly larger numbers of Park visitors (Bergstresser et al. 2002). Archeological investigations conducted in 1984, 1991–1992, and 2001 concluded that the Site was used for waste disposal from 1905

(or earlier) into the 1930s. The types of debris observed consisted primarily of metal, glass, and ceramic, which likely had originated from the hotels and camps active in the Yosemite Valley at the time, as suggested by the manufacturing dates on materials and types of materials recovered during excavations

(NPS 1990).

In 1991 and 1992, the NPS screened the soil at the Site to remove the larger pieces of trash. The Site was then regraded to approximately the grade prior to waste disposal activities and replanted. In 1996 and 1997, major floods in Yosemite Valley might have modified the debris exposures observed in 1980 and during the

1991– 1992 archeological investigations. NPS entered into a consent agreement with the California

Department of Toxic Substances Control (DTSC) in 2001, wherein NPS agreed to determine the nature and extent of contamination at various sites within the Park, including this Site.

3.3 Previous Cleanup Actions (2.10)

In 1991 and 1992, the NPS screened the soil at the Site to remove the larger pieces of trash. Portions of the Site were eroding into the Merced River due to the lateral migration of the river channel. Because Park visitors commonly use the area surrounding the Site, the exposure of materials such as glass, ceramic shards, and rusty metal and the erosion of these artifacts into the river constituted a safety hazard. The cleanup, which specifically targeted trash and debris, used a large excavator to dig several trenches through the known trash deposits, and archeologists monitored the trenching activity. The excavated material was processed in an on-site screening plant that removed larger debris items from the sandy soil. The screened soil, which still contained small fragments of glass and metals, was used to refill the trenches and recontour the site. No other cleanup actions are known to have occurred at the Site.

3.4 Waste Characteristics (2.4)

Waste debris at the Site includes domestic trash (e.g., cooking pans, bowls, pitchers, utensils, crushed cans, stove parts, and food storage containers), glass, ceramics, automotive machinery and related wastes, paint cans, 55-gallon drums, and a layer of burned material that was thought to be the result of regular on-site burning. It is unknown whether aqueous film forming foam (AFFF) may have been used in relation to debris burning activity at the Site. Most large pieces of trash (e.g., drums) were removed during the 1992 soil screening activities; however, some fairly large items of debris were noted at the Site during a site visit in 2014. Waste materials exposed at the surface, including metallic debris, represent a potential safety hazard. Other than what can be deduced from field observations during archeological investigations (as described in Engineering Evaluation/Cost Analysis (EE/CA) Section 2.3) and site investigations (as described in EE/CA Section 2.11), documentation of waste disposal activities is not available.

Based on the type of waste present, soil at the Site may be impacted by metals (from paint and construction, farm-related equipment, and automotive machinery), polycyclic aromatic hydrocarbon (PAHs) (oil spills from automotive parts), semivolatile organic compounds (SVOCs) including pentachlorophenol (PCP) (a wood preservative for power line poles and fences), total petroleum hydrocarbons (TPH) (from motor oil or diesel), and dioxins/furans (from regular burning of wastes). Each class of contaminants has been detected in site media, as further described in EE/CA Section 2.11.2.

3.5 Historically/Culturally Significant Features (2.3)

The Site was studied by R. Tagg in 1984 to determine its historical and archeological significance. Historical accounts suggested the dump was in use prior to 1929, primarily by the old Curry Company Lodge and the

U.S. Army, which at one time had a camp near Yosemite Creek. Tagg found artifacts indicative of domestic trash possibly from military camps or hotels and dated most items in the period from 1880 to 1920. The

NPS archeological investigation of 1991–1992 found various hotel, household, and automotive items. A layer of compacted cans, assumed to be from the can crusher at the Yosemite Valley incinerator, also was found at the Site. Other articles observed included paint cans and at least one 55-gallon metal drum. The

1991–1992 and 2001 investigations indicate that the Site was used as a dump from 1905 or earlier into the

1930s. The Site contains intact dump deposits spanning several decades, with time periods separated enough spatially so that archeologists can draw out meaningful inferences about changes in the behavior of visitors and the tourist industry in the Valley through time. However, due to the extensive previous archeological work at the site and redundancy of remaining artifacts with those already catalogued, Yosemite archeologists, in conjunction with the State Historic Preservation Officer, determined in early 2021 that the Site no longer retains any further research potential and is therefore not eligible for listing in the

National Register of Historic Places.

The nearby area also has several culturally significant features. Located adjacent to the Site, the Merced

River is designated as a National Wild and Scenic River. El Capitan, located approximately 2,000 feet from the Site, is a prominent rock formation and one of the most popular features within the Park.

3.6 Current/Future Land Uses (2.13)

The Site is located within the Park and within the river corridor of the Merced River, which is designated as a National Wild and Scenic River. The Site is currently undeveloped with the exception of a section of the

Valley Loop Trail, a significant trail for Yosemite Valley that crosses the Site. Because of its proximity to the scenic Merced River, hikers travel through the Site frequently. According to the Final Merced River Final

Comprehensive Management Plan and Environmental Impact Statement (MRP), the Site is designated as a meadow restoration area (NPS 2014a).

The proposed future habitat type for the Site, as outlined in the MRP, is wet meadow and riverbank. Planned activities near the Site, as part of the meadow restoration, include re-routing of the Valley Loop Trail to an upland area, re-vegetating abandoned sections of the Valley Loop Trail with native meadow species, and removing informal trails to reduce meadow fragmentation. Additional management activities may include re-vegetation, prescribed fire, mechanical removal of conifers, and infrastructure redesign.

4.0 PHYSICAL AND ENVIRONMENTAL SETTING

Much of the information in this section is derived from the EE/CA, Section 2 (CDM 2020). Subsection headings indicate the EE/CA section from which text in that subsection is derived. In some cases, text in this section is copied verbatim from the EE/CA; in other cases, text in this section is condensed from the

EE/CA, and/or additional clarifying information has been added.

4.1 Site Topography and Features (2.1)

Site topography is hummocky and slopes slightly toward the river. The DUs closest to the river are relatively free of vegetation due to numerous activities, including human disturbance, trash disposal, and natural river processes. DUs further to the west and north are vegetated with trees, brush, and grasses. Debris, composed of predominately metal, glass, and ceramic, is visible at the ground surface, and subsurface debris has been exposed at the Merced River bank due to erosion by the lateral migration of the river.

The Yosemite Lodge complex is located to the east of the Site, and the village of El Portal, California, is approximately 11 miles to the west. Summer visitors and year-round residents inhabit both settlements. The Yosemite Valley Loop Trail traverses the Site on the southern end near the Merced

River, and the Site receives foot traffic from Park visitors frequenting the Loop Trail.

4.2 Climate (2.7)

Yosemite Valley receives an average annual precipitation of 37 inches, with contributions from summer rain and winter snow. Winter in the Park is cold and wet, with over 70% of the annual precipitation falling between November and March, usually as snow. Summers in the Park are warm and dry. Daytime temperatures in Yosemite Valley sometimes reach 100°F during summer, while nights are cool. Spring and fall months are highly variable, with sunny and relatively warm days and occasional winter storms.

4.3 Regional and Local Geology (2.5.1)

Yosemite Valley is a product of the joining of the Merced Glacier and the Tenaya Glacier during the Last

Glacial Maximum glaciation, locally known as the “Tioga” glaciation. The formation of a lake in Yosemite

Valley following the glaciation resulted in the deposition of alluvial, fluvial, and glacial outwash sediments, which include interbedded layers of boulders, gravel, sand, very fine rock dust, and blue silt. Three layers of sediments in the Yosemite Valley have been previously documented (Gutenberg et al. 1956). The total maximum thickness of these layers is estimated at 1,900 feet.

The Site is situated on a stream terrace of the Merced River that formed from recessional moraine deposition. This process, in addition to stream erosion and weathering of the exposed granitic Sierra

Nevada batholith, has formed the present-day landscape found in the Yosemite Valley. Granitic bedrock associated with the Sierra Nevada Batholith lies more than 1,000 feet below the native soils at the Site

(Harden 2004).

Native soils are mainly of granitic origin with minor contributions from Paleozoic metamorphic rocks (Norris and Webb 1990). Previous investigations performed by NPS archeologists and Shaw (Shaw 2011) describe the native soil as silty sand with organic debris and gravel. During the excavations to 6 feet below ground surface (bgs), non-native coarse sand with gravel was reported to cap the debris areas. With exception of the Merced River, no surface water was observed during previous investigations in 1999, 2001, or 2010.

4.4 Surface Water Hydrology (2.6)

The Site is situated adjacent (to the northwest, north, and northeast) to the Merced River. Surface water has only been observed at the Site during large annual snowmelt floods and during large wintertime “rain on snow” floods. The Site was impacted by major floods in December 1937, November 1950, December

1955, December 1964 and January 1997. Flood-related dry channels were observed along the eastern and northern edges of the Site. Riverine upper perennial wetlands occur along the Merced River in the vicinity of the Site (U.S. Fish and Wildlife Service [USFWS} 2001); however, no wetlands occur within the boundaries of the Site. No site-specific surface water hydrologic investigations have been conducted at the

Site.

4.5 Hydrogeology (2.5.2)

The shallow groundwater below the Site occurs within an alluvial aquifer. Investigations describe the subsurface as consisting primarily of sand or silty sand. Debris from the former waste disposal operations has been noted to a depth of approximately 4 feet bgs. The limited groundwater data indicate that groundwater levels are deeper than the debris under normal conditions; however, in years when the Merced

River is bank full or greater, groundwater is almost certainly in contact with the debris. Groundwater field measurements are not typically made when the river is high.

NPS installed one piezometer (MW-1) in April 2008 and monitored it for groundwater levels from April through September 2008. MW-1 was installed with a bottom screened depth of 8.9 feet bgs. During this time, groundwater levels at the piezometer peaked at 4.9 feet bgs in May and gradually fell until the well went dry (i.e., groundwater levels were greater than 8.9 feet bgs) in June 2008 and remained dry for the remainder of the monitoring period (i.e., through September 2008).

In 2010, Shaw conducted a facility investigation, the results of which were reported in the 2011 Facility

Investigation Report (FIR) (Shaw 2011). As a part of this facility investigation, three temporary groundwater monitoring wells were installed in April 2010. The bottom screened depths of MW-2, MW-3, and MW-4 were

11 feet bgs, 7 feet bgs, and 11 feet bgs, respectively. During the initial depth to groundwater measurements in April 2010, groundwater was observed between 9.35 feet bgs and 10.45 feet bgs. Depths to groundwater at follow-up groundwater sampling events in February 2016 and April 2016 have been between 6.02 feet bgs and 10.13 feet bgs. During the 2017 groundwater investigation where groundwater samples were taken from 13 temporary boreholes, groundwater depth was encountered between 9 feet bgs and 13 feet bgs.

Given the limited groundwater data, it is assumed that typical shallow groundwater flow is toward the river or in the downstream direction near the river. Groundwater may have variable flow direction throughout the year as the adjacent Merced River’s volume changes. During flood conditions, it is possible that the groundwater flow direction may reverse for a brief period of time. This is dependent on the elevation of the water table in the alluvial aquifer versus the elevation of surface water in the river.

4.5.1 Groundwater Use (2.5.2)

The nearest drinking water wells are located east of the Yosemite Lodge complex, approximately 1.8 miles upstream along the Merced River. The nearest downstream settlement with associated drinking water wells is El Portal, California, approximately 11 miles west of the Site. No permanent drinking water wells currently exist at the Site.

4.6 Ecological Setting (2.8)

4.6.1 Habitat (2.8.1)

The Site is within the lower montane vegetation zone and located adjacent to the Merced River. During the

2016 investigation, the field team described the habitat in the site vicinity as consisting of mixed conifer forest of white fir (Abies concolor), ponderosa pine (Pinus ponderosa), and incense-cedar (Calocedrus decurrens). Riparian vegetation consisted of grasses and sedges in the understory, with a generally open canopy of the conifers listed above, black cottonwood (Populus balsamifera trichocarpa), California black oak (Quercus kelloggii), and willows (Salix sp.) and shrubs, including manzanita (Arctostaphylos sp.).

The 2016 field team documented ecological receptors observed during the investigation. One crayfish was observed in the Merced River upstream of the Site. No fish or other aquatic wildlife were observed during the sampling activities. A vole was observed pulling vegetation into a hole on the riverbank and several gray squirrels were observed foraging along the river. Raccoon, rabbit, and domestic dog tracks were observed in the site vicinity. An American dipper (Cinclus mexicanus) was observed foraging in the river.

Other birds observed during sampling activities included common raven (Corvus corax), Steller’s jay

(Cyanocitta stelleri), downy woodpecker (Picoides pubescens), northern flicker (Colaptes auratus), red-breasted nuthatch (Sitta canadensis), mountain chickadee (Poecile gambeli), brown creeper (Certhia americana), and darkeyed junco (Junco hyemalis).

4.6.2 Species of Special Concern (2.8.2)

About 40 species have special status in the Park. Some of the Park’s threatened, endangered, and sensitive animal species include the Yosemite toad (Anaxyrus canorus), California red-legged frog (Rana draytonii), mastiff and spotted bats (Eumops perotis and Euderma maculatum respectively), the Sierra Nevada red fox (Vulpes vulpes necator), the spotted owl (Strix occidentalis), the California wolverine (Gulo gulo; almost certainly locally extirpated according to NPS), the Sierra Nevada bighorn sheep (Ovis canadensis sierrae), the northern goshawk (Accipitridae gentilis), the willow flycatcher (Empidonax traillii), Bohart’s blue butterfly

(Philotiella speciosa bohartorum), and one fish species (the hardhead, Mylopharadon conocephalus).

There are several federally listed amphibians in the Valley, such as the California red-legged frog (CARLF, Rana draytonii), which may be present on roadways, in riverbanks, or in meadows. To avoid hitting amphibians with vehicles, driving in the Park at night should be avoided, particularly during warm, wet weather. It is also recommended that escape ramps be fitted on any open pits/trenches or that they be covered if they are left unfilled overnight to prevent entrapment of wildlife.

During the 2010 Merced River riparian vegetation assessment, wildlife evaluations for amphibians, reptiles, aquatic invasive species, birds, and bats were conducted using visual and acoustic surveys within the

Yosemite Valley. Two species of special concern were identified in the Yosemite Valley near the Site, including the spotted bat (Euderma maculatum) and western mastiff bat (Eumops perotis). CARLF were re-introduced to Yosemite Valley in 2016 and surveys for them have not been completed at this project site.

Birds may nest both on the ground and in trees in this area. Work may not be performed during the nesting period of May 1-July 31.

4.7 Sensitive Environments (2.9)

The USEPA defines sensitive environments as “a terrestrial or aquatic resource, fragile natural setting, or other area with unique or highly-valued environmental or cultural features.” (USEPA 1991a) The Site is considered a sensitive environment because it is located inside the Park, along the Merced River, and in close proximity to wetlands. National parks, national wild and scenic rivers, and wetlands are defined as sensitive environments by the USEPA (USEPA 1992c).

Based on the MRP, the Site is fully within the river corridor of the Merced River. The Merced River is designated as a National Wild and Scenic River, and the segment of the Merced River that the Site is located along is designated as Scenic. Under the 1982 guidelines for implementing the Wild and Scenic

Rivers Act (47 Federal Register [Fed. Reg.] 39454), selected rivers are viewed as sensitive ecosystems that must be “managed to protect and enhance the values for which the river was designated, while providing for public recreation and resources uses which do not adversely impact or degrade those values.”

This also includes the management of the river corridor (NPS 2014b).

The USFWS National Wetlands Inventory identifies an area of freshwater emergent wetlands located just to the northwest of the Site. The MRP also provides an assessment of the wetlands near the Site. It identifies an area of palustrine emergent wetlands just to the northwest of the Site and an area of palustrine forested wetlands within the Site along near the southern boundary.

4.8 Site Contaminants (2.11)

4.8.1 Media/Contaminants of Concern (2.11.2)

The media of concern at the Site are soil, groundwater, sediment, and porewater. Surface water also was evaluated as a medium of concern in the risk assessment; however, site-specific surface water data were not collected during the investigations. Site investigations have shown the presence of metals, PAHs, SVOCs, TPH, and dioxins/furans.

4.8.2 Sources of Contamination (2.14.1)

The Site was used as a waste disposal area from approximately 1905 to the early 1930s. Waste debris at the Site includes domestic trash, glass, ceramics, automotive machinery and related wastes, paint cans, 55-gallon drums, and a layer of burned material that was thought to be the result of regular on-site burning.

Although most large pieces of trash (e.g., drums) were removed during the 1992 soil screening activities, larger items of debris were noted during the 2014 site visit. Site investigations have shown that waste debris is distributed across the Site, primarily within the top 4 feet of soil, in a series of distinct debris zones. Based on the type of waste present, the Site may be impacted by metals (from paint and construction, farm-related equipment, and automotive machinery), PAHs (oil spills from automotive parts), PCP (a wood preservative for power line poles and fences), TPH (from motor oil or diesel), and dioxins (from regular burning of wastes).

4.8.3 Summary of Investigations (2.11.1)

In 1990, the NPS Water Resources Division conducted an investigation of the Site. The investigation noted many occurrences of debris in the river bank and on the ground surface some distance from the river (NPS

1990). Composite soil samples resulted in detections of barium, lead, and mercury. In 1991 and 1992, NPS conducted an archeological investigation, as reported in the El Capitan Picnic Area Dumpsite Status Report

(NPS 1992). The investigation identified a layer of burned material that was thought to be the result of regular on-site debris burning. The investigation found various hotel, household, and automotive items, and it was determined that the Site is culturally significant and eligible for the National Register of Historic

Places.

In 2001, IT Corporation conducted a Focused Site Inspection (FSI) at the Site. All test pit samples collected exceeded limits for arsenic, and three samples exceeded limits for lead. (It should be noted that it was not specified in the EE/CA which limits were exceeded.) Diesel and motor oil range organics were detected in most of the soil samples. PAHs were detected in three samples, and dioxins were detected in one soil sample. The findings of the FSI were compiled in the Draft Final Report, Focused Site Inspection of El

Capitan Waste Accumulation Area, Yosemite National Park, California, dated September 2002 (IT

Corporation 2002). DTSC reviewed the draft report and provided comments and observations of data gaps to be addressed through additional investigation. Archeological monitoring was also provided during the

FSI field work for the shovel or backhoe excavation of 25 test pits. Archeologists observed and recorded artifacts that were uncovered, and in 2002 wrote the report Yosemite’s Garbage, Archeological

Investigations at the El Capitan Site (Bergstresser et al 2002).

In 2010, Shaw, previously IT Corporation, conducted an additional investigation at the Site in order to fill data gaps identified by DTSC in the 2001 FSI, including verification of elevated lead detections in the 2001 results, completion of new background and investigative soil borings, construction of monitoring wells, and sampling of groundwater. X-ray fluorescence (XRF) data identified an area of elevated lead in surface soils in an area with no subsurface debris. Results of the 2010 investigation were reported in the Final Facility

Investigation Report, dated December 2011 (Shaw 2011).

In July 2014, an Approval Memorandum was prepared by the Park and signed by the NPS Regional Director for a non-time-critical removal action (NTCRA) to be conducted at the Site via an EE/CA investigation. In coordination with NPS and DTSC, a sampling and analysis plan (SAP), site-specific health and safety plan

(HASP), and community involvement plan (CIP) were prepared in 2015. In November 2015, NorCal completed a geophysical survey of the Site, using vertical magnetic gradient, electromagnetic terrain conductivity, and ground-penetrating radar methods. The geophysical survey revealed substantially larger areas of subsurface waste than previously identified. Since the previously identified waste area was fairly well-bounded, NPS decided to plan for staggered field sampling investigations at the Site (two separate phases) to allow for a second geophysical survey to be conducted at the Site the following year, in an attempt to fully capture the site boundaries. During this period, sediment and porewater sampling within the river and field sampling via XRF within surface soil were performed to delineate an area with elevated concentrations of lead.

In July 2016, NorCal completed a second geophysical survey at the Site within the Phase 2 area. The survey fully captured the boundaries of subsurface waste at the Site. The areas of the 2015 and 2016 geophysical surveys are shown on Figure 4. In September 2016, an amendment to the SAP was prepared and implemented through the Phase 1 soils investigation at the Site. A combination of thirty-one (31) test trenches and ten (10) test pits were excavated to delineate boundaries of subsurface waste. Seven decision units (DUs) (DU1 through DU7) were sampled using incremental sampling methodology (ISM) in the surface (0 to 6 inches bgs) and subsurface soils (6 to 48 inches bgs). Concurrent to the excavation field work at the Site, the cultural resources firm (Pacific Legacy) conducted historical archeological data recovery treatment measures to avoid an adverse effect determination to CA-MRP-1196H (the archeological identifier for the Site). These measures involved implementing an archeological work plan of field monitoring and research that would lead to refined understanding of the Site’s cultural resources.

Pacific Legacy also performed site surface inventory and mapping activities within the Phase 2 area.

In 2017, additional test trenches were excavated to delineate boundaries of subsurface waste within the

Phase 2 area. Six site DUs (DU8 through DU12 and DU15) and one background DU (DU 16) were sampled using ISM in the surface (0 to 6 inches bgs) and subsurface soils (6 to 48 inches bgs). In addition, groundwater monitoring was conducted at 13 temporary sampling locations. Sample locations included 13 site DUs (DU1 through DU12 and DU15) and one background DU (DU16) (see Figure 5).

4.8.4 Data Summary (2.11.3)

Debris

According to the FIR (Shaw 2011), 2010 field observations indicated subsurface debris was laterally discontinuous across the Site. Most subsurface debris occur in two general areas of the Site: a roughly circular area in what was later designated as DU-1 and an oblong area in what was later designated as

DU-3. These areas are noted on Figures 3 and 4. The surface area of the DU-1 debris is estimated to be approximately 0.2 acre with an average debris thickness of 1.25 feet. The surface area of the DU-3 debris is estimated to be approximately 0.1 acre, with an average debris thickness of 2 feet. The debris-laden soil present in the waste accumulation area consisted primarily of metal, with some glass in sandy soil.

Figure 3 shows the results of the 2015 and 2016 geophysical surveys. Areas with surface and subsurface anomalies, which comprise areas of vertical magnetic gradient anomalous zone and terrain conductivity anomalous zone, are outlined in Figure 3. Phase 1 soil investigations were preliminarily designed based on findings from the 2015 geophysical survey results of Geophysical Survey Area 1.

Based on the 2015 geophysical survey data for Geophysical Survey Areas 1, 2, and 3, it was concluded that additional areas could potentially be impacted by historical waste disposal operations. As such, the limits of the Site were increased from 2 acres to 19 acres, and another geophysical survey was performed in the site expansion area as part of 2016 Phase 1 soil investigation (CDM Smith 2017), as outlined in

Figure 5. The results from the 2016 NorCal geophysical survey confirmed that surface and subsurface anomalous zones are in the site expansion area, as presented in Figure 5.

Test trenches and test pits were constructed around and within the boundaries of the preliminary DUs to confirm the lateral and vertical boundaries of the waste piles, respectively. Based on findings from test trenches and test pits, it was found that the lateral boundaries of waste piles were smaller than the boundary of the preliminary DUs. In addition, it was found that wastes in the waste piles are generally confined to the top 4 feet of soil. The lateral boundaries of the DUs were refined based on the lateral limits of the waste piles, and the depth of the DUs were limited to 4 feet bgs. Figure 6 shows the boundaries of the refined

DUs. Detailed information regarding the test trenches and test pits is in the 2016 Report of Findings (CDM

Smith 2017) and 2017 Report of Findings (CDM Smith 2018).

Soils

Soil samples during the 2001 and 2010 investigations were analyzed for metals, TPH, PAHs, volatile organic compound (VOCs), SVOCs, and polychlorinated biphenyls (PCBs). In addition, pesticides and herbicides samples were collected during the 2010 investigation and limited sampling of dioxin/furans was conducted during the 2001 investigation. Soil sampling results indicate the presence of metals and PAHs above the screening values presented in the FIR (Shaw 2011). Metals that exceeded at least one of the screening levels presented in the FIR included antimony, lead, cadmium, arsenic, and iron. Approximately

15% of soil samples exceeded screening values for lead, with a maximum concentration of 19,100 milligrams per kilogram (mg/kg). Additionally, certain VOCs, TPH, pesticides, and dioxin/furans were detected in soil samples but well below screening levels. Field screening of metals was conducted during the 2010 investigation. Samples analyzed by XRF indicated levels of lead, antimony, arsenic, and cobalt exceeding screening levels. In particular, lead concentrations exceeded at least one screening level in 14 of the 73 primary samples and 15 of the 18 step out samples, with a maximum concentration of 5,589 mg/kg. Additional XRF measurements of surface soil were conducted during the 2016 investigation. Lead and zinc are the two metals that were consistently detected above the soil screening level.

The 2016 and 2017 CDM Smith investigations collected surface and subsurface ISM soil samples from 13 site DUs (DU1 through DU12 and DU15) and one background DU (DU16) (see Figures and 6). The DU boundaries were initially based on the results of the geophysical surveys and were refined by the results of the test trenches. There were 13 metals (antimony, arsenic, barium, cadmium, chromium, copper, lead, mercury, molybdenum, nickel, silver, thallium, vanadium, and zinc) that were found to have concentrations above the risk assessment screening levels. In addition, two TPH constituents (diesel range organics and motor oil range organics) and dioxin/furans toxic equivalency quotient (TEQ) were found to have concentrations above the risk assessment screening levels in a small number of locations. None of the other types of constituents (SVOCs, PAH, and pesticides) were detected above risk assessment screening levels. Antimony, arsenic, barium, chromium, lead, molybdenum, thallium, vanadium, and zinc are the metals with analytical results of ISM soil samples that are consistently higher than the risk assessment screening levels. Arsenic, chromium, lead, vanadium, and zinc are frequently detected at concentrations one order of magnitude higher than the risk assessment screening levels. While XRF measurements identified an area of elevated lead concentrations at DU4, measured concentrations of lead in the ISM surface soil samples were highest in DU5.

Detected concentrations across the site DUs are generally similar; DU15 tended to have lower concentrations relative to the other site DUs. Several PAHs and PCP were detected across all site DUs, but only one PAH (2-methylnaphthalene) was detected in the background DU. In addition, dioxin/furan congeners were frequently detected in site DUs; however, only four congeners were detected in the background DU, and TEQ concentrations in the background DU were about an order of magnitude lower than the site DUs. These results support the conclusion that these contaminants are likely to be site-related.

Although several metals (beryllium, cobalt, molybdenum, thallium, and vanadium) had concentrations in site soils that were similar to the background DU, several metals (antimony, cadmium, copper, lead, mercury, silver, and zinc) had concentrations more than one order of magnitude greater in site DUs than in the background DU. Detailed information regarding the 2016 and 2017 soil investigations can be found in the 2016 Report of Findings (CDM Smith 2017) and 2017 Report of Findings (CDM Smith 2018) respectively.

Groundwater

Groundwater samples were collected at four monitoring wells in May 2010 and analyzed for metals, major cations, PAHs, VOCs, PCBs, SVOCs, pesticides, and herbicides. Follow-up groundwater sampling in July

2010 included only metals and VOCs analysis at three monitoring wells. Groundwater results from the 2010 investigation show detections of metals and VOCs; however, the concentrations were well below maximum contaminant level (MCLs) for all analytes.

As part of the 2016 investigations, groundwater samples were collected from MW-1, MW-2, and MW-4, but no sample was collected from MW-3 due to insufficient water (water level was reportedly only 1 foot above bottom of screen). There were six metals (arsenic, chromium, cobalt, copper, lead, and vanadium) that were found to have concentrations above the risk assessment screening levels. None of the other types of constituents (SVOCs, PAH, pesticides, and TPH) were detected at above the risk assessment screening levels. Metal concentrations in groundwater are generally highest in MW-4, a downgradient well that is most likely to be impacted by contaminants, and lowest in MW-1.

As part of the 2017 investigations, groundwater monitoring locations were placed in areas upgradient of the waste areas (G01–G03; Upgradient DU), within the waste areas (G04–G06; Site DUs), and downgradient of the waste areas (G07–G13; Downgradient DU). Groundwater samples were analyzed for VOCs, SVOCs, PAHs, TPH, pesticides, metals, and hardness. With few exceptions, no VOCs, SVOCs, TPH, or pesticides were detected in groundwater samples. Metals, PAHs, and PCP were detected in most groundwater samples. Most metals were detected in groundwater samples in both the total and dissolved fraction. In general, total metal concentrations were higher than dissolved metal concentrations by an order of magnitude. PAHs and PCP were detected in groundwater samples from two site DUs (G01, G04) and two downgradient DUs (G09, G10); all other DUs were non-detect for PAHs. Overall, three analytes were detected above MCLs (arsenic, lead, and benzo(a)pyrene). Benzo(a)pyrene exceeded the MCL (0.2 microgram per liter [μg/L]) at two locations with a maximum concentration of 0.44 μg/L. Total arsenic exceeded the MCL (10 μg/L) at six locations with a maximum concentration of 29.3 μg/L. Total lead exceeded the MCL (treatment technique action level of 15 μg/L) at two locations with a maximum concentration of 24.8 μg/L. While total arsenic and total lead concentrations exceeded the MCLs, dissolved arsenic and lead concentrations were well below the MCLs. This indicates arsenic and lead concentrations are bound up in suspended particles.

Several PAHs and PCP were detected in a few Site and downgradient locations, but these chemicals were not detected in upgradient locations. These results support the conclusion that these contaminants are likely to be site-related. In general, metal concentrations tended to be higher in Site and downgradient locations. Except for dissolved copper, Site and downgradient concentrations were usually within one order of magnitude of upgradient concentrations. On average, dissolved concentrations of copper in Site and downgradient groundwater were about 20 times higher than in upgradient groundwater. Detailed information regarding the 2016 and 2017 groundwater investigations can be found in the 2016 Report of

Findings (CDM Smith 2017) and 2017 Report of Findings (CDM Smith 2018).

Sediment

Sediment samples were collected at 10 sampling locations along five transects during the 2016 investigation. Only TPH (motor oil) and metals (seven metals—arsenic, barium, chromium, cobalt, lead, thallium, and vanadium) were found to have concentrations above the risk assessment screening levels.

None of the other types of constituents (SVOCs, PAH, pesticides, and dioxin and furans) were detected at above the risk assessment screening levels. Concentrations were generally similar at each of the five transects sampled.

Arsenic and vanadium are the only metals frequently detected at concentrations one order of magnitude higher than the risk assessment screening levels. Detailed information regarding the 2016 sediment investigation can be found in the 2016 Report of Findings (CDM Smith 2017).

Sediment Porewater

Porewater samples were collected at 10 sampling locations along five transects during the 2016 investigation. Six metals (antimony, arsenic, barium, copper, nickel, and thallium), one PAH

(benzo(b)fluoranthene), and one SVOC (pentachlorophenol) were found to have concentrations above the risk assessment screening levels. None of the other types of constituents (VOCs, pesticides, and TPH) were detected above the risk assessment screening levels. Detailed information regarding the 2016 porewater investigation can be found in the 2016 Report of Findings (CDM Smith 2017).

4.8.5 Human Receptors of Concern

The Yosemite Valley Loop Trail traverses the Site on the southern end near the Merced River, and the Site receives foot traffic from Park visitors frequenting the Loop Trail. In the future, NPS plans to reroute the existing hiking trail and restore the riparian habitat. Therefore, Park visitors are the primary human population of concern under both current and future use scenarios. Park visitors may engage in various activities, including fishing and wading/swimming in the river, picnicking, and hiking. For the Park visitor exposure scenario, it is assumed this population may include children (less than 6 years old), older children

(6 to 16 years old), and adults (greater than 16 years old).

It is anticipated that NPS employees may periodically visit the Site as part of normal outdoor maintenance activities (e.g., Park rangers monitoring Park use by visitors and wildlife) under both current and future conditions. NPS employees may also engage in future archeological excavations to further characterize and document waste debris at the Site, although such excavations are unlikely due to the lack of remaining data potential and extensive sampling that has previously occurred at the Site. Although no construction activities are planned at the Site, meadow and riparian habitat restoration projects may occur in the area;

thus, a future restoration worker scenario was evaluated. For the NPS employee and restoration worker exposure scenarios, the receptors of interest are adults.

5.0 REGULATORY FRAMEWORK

Information in this section is derived from the EE/CA, Section 1.1 (CDM 2020). In some cases, text in this section is copied verbatim from the EE/CA; in other cases, text in this section is condensed from the EE/CA, and/or additional clarifying information has been added.

The NPS is authorized under CERCLA, 42 United States Code (USC) Section 9601 et seq., to respond as the lead agency to a release or threatened release of hazardous substances and/or a release or threatened release of any pollutant or contaminant that may present an imminent and substantial danger to public health or the environment on NPS-managed land.

CERCLA’s implementing regulations, codified in the National Oil and Hazardous Substances Pollution

Contingency Plan (NCP), 40 Code of Federal Regulations (CFR) Part 300, establishes the framework for responding to such releases and threatened releases. The NCP prescribes two processes for responding to releases: (1) removal actions and (2) remedial actions (see NCP Sections 300.400 through 300.440).

Previous investigations have led to the determination that the Site presents a current or potential threat to public health and/or to the environment and that a removal action is appropriate at the Site as specified in

40 CFR, Section 300.415(b). This determination was formalized in an EE/CA Approval Memorandum, signed on July 31, 2014, by Christine Lehnertz (Pacific West Regional Director, National Park Service) and is included in the Administrative Record for the Site.

This EE/CA Report upon which this NTCRAWP is based (CDM 2020) was generated in accordance with the NCP, 40 CFR Section 300.415(b)(4)(i), U.S. Environmental Protection Agency’s (USEPA) Guidance on

Conducting Non-Time-Critical Removal Actions Under CERCLA (USEPA 1993a), and the U.S. Department of the Interior (USDOI) Central Hazardous Materials Fund (CHF) CERCLA Process for CHF Projects

Environmental Compliance Memorandum (ECM) 16-3 (USDOI 2016).

6.0 REMOVAL ACTION

Much…