Final_EE-CA_Report.pdf

Department of the Interior National Park Service

Devils Postpile National Monument Madera County, California

Engineering Evaluation/Cost Analysis Report Devils Postpile National Monument

Lead Impacted Surface Soil at Potable Water Tank Madera County, CA

March 21, 2014

Prepared by:

Rafael Macedo Project Engineer II

Holly A. Trejo, PG Project Manager

March 21, 2014 March 21, 2014

Devils Postpile National Monument March 21, 2014 i

TABLE OF CONTENTS

Acronyms and Abbreviations ..................................................................................... iii Executive Summary ...................................................................................................... v

1.0 Introduction

1.1 Authority

1.2 Purpose and Objectives

1.3 Background/Site History

2.0 Site Characterization

2.1 Site Description

2.1.1 Geology and Geohydrology

2.1.2 Climate, Vegetation and Wildlife

2.1.3 Land Uses

2.2 Site History

2.2.1 Water Tank Operational History

2.3 Summary of Previous Investigations

2.4 2013 EE/CA Field Investigations

2.4.1 Site-Specific Background Data

2.5 Nature and Extent of Contamination

2.5.1 Constituents of Potential Concern

2.5.2 Extent and Volume of Impacted Soils

2.6 Streamlined Risk Assessment

2.6.1 Preliminary Exposure Pathways

2.6.2 Human Risk Screening Criteria

2.6.3 Ecological Risk Screening Criteria

2.6.4 Site Specific Screening Level

2.6.5 Contaminant of Concern for Removal Action

2.6.6 Risk Summary

3.0 Removal Action Objectives & Applicable or Relevant and Appropriate Requirements

3.1 Removal Action Objectives

3.2 Removal Action Justification

3.3 Identification of Applicable or Relevant and Appropriate Requirements

3.3.1 Chemical-Specific ARARs

3.3.2 Location-Specific ARARs

3.3.3 Action-Specific ARARs

4.0 Identification and Screening of Removal Action Alternatives

4.1 Identification of Removal Action Technologies

4.2 Screening of Removal Action Technologies

4.3 Assembly of Removal Action Alternatives

5.0 Evaluation of Removal Action Alternatives

5.1 Alternative 1: No Action

5.1.1 Effectiveness of Alternative 1

5.1.2 Feasibility/Implementability of Alternative 1

5.1.3 Cost of Alternative 1

5.2 Alternative 2: Engineering/Institutional Controls

5.2.1 Effectiveness of Alternative 2

ii

5.2.2 Feasibility/Implementability of Alternative 2

5.2.3 Cost of Alternative 2

5.3 Alternative 3: Excavation, On-Site Consolidation/Institutional Controls

5.3.1 Effectiveness of Alternative 3

5.3.2 Feasibility/Implementability of Alternative 3

5.3.3 Cost of Alternative 3

5.4 Alternative 4: Excavation and Off-Site Disposal

5.4.1 Effectiveness of Alternative 4

5.4.2 Feasibility/Implementability of Alternative 4

5.4.3 Cost of Alternative 4

5.5 Comparative Analysis of Removal Action Alternatives

6.0 Conclusions and Recommendations

6.1 Recommended Removal Action Alternative

6.2 Removal Schedule

FIGURES

Figure 1: Site Vicinity Map Figure 2: Site Features Figure 3: Decision Unit Layout Figure 4: Lead Concentration Trend (Power Trendline) Figure 5: Human Health Risk Conceptual Model Figure 6: Ecological Risk Conceptual Model Figure 7: Alternative 2 – Engineering/Institutional Controls Figure 8: Alternative 3 – Excavation, On-site Consolidation/Institutional Controls Figure 9: Alternative 4 – Excavation/Off-site Disposal

TABLES

Table 1: Contaminant of Concern Table 2: Removal Action Justification Table 3: Chemical-Specific ARARs Table 4: Location-Specific ARARs Table 5: Action-Specific ARARs Table 6: Removal Action Technologies Table 7: Removal Action Technology Screening Table 8: Comparative Analysis of Removal Action Alternatives Table 9: Removal Action Alternative Selection

ATTACHMENTS

Attachment A Approval Memorandum Attachment B Laboratory Analytical Reports and Chain of Custody Documentation Attachment C Risk Screening Levels and Background Calculations Attachment D Cost Estimates Attachment E Responsiveness Summary iii

ACRONYMS AND ABBREVIATIONS

ARAR Applicable or Relevant and Appropriate Requirement

AUF Area Use Factor bgs below ground surface

CAMU Corrective Action Management Unit

CCR California Code of Regulations

CE Common Era

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act

CESA California Endangered Species Act

CFR Code of Federal Regulations

COC contaminant of concern

COPC constituent of potential concern

CSM conceptual site model cy cubic yard

DTSC Department of Toxic Substances Control

ECM Environmental Cost Management, Inc.

ED exposure dose

EE/CA Engineering Evaluation/Cost Analysis

EPA United States Environmental Protection Agency

EPC exposure point concentration

°F Degrees Fahrenheit

IC Institutional Control

HI Hazard Index

HQ Hazard Quotient

ISM Incremental Sampling Methodology

MCL maximum contaminant levels mg/kg milligrams per kilogram mg/L milligrams per liter

MI multi-increment

MOU Memorandum of Understanding

NCP National Oil and Hazardous Substance Pollution Contingency Plan

NPS National Park Service

NRCS Natural Resource Conservation Service

NTCRA non-time critical removal action

OM&M operation, maintenance, and monitoring

PA Preliminary Assessment

PRG Preliminary Remediation Goal

QA quality assurance

QAPP Quality Assurance Project Plan

QC quality control

RAO Removal Action Objectives iv

RCRA Resource Conservation and Recovery Act

RSL Regional Screening Level

RSV risk screening value

RWQCB Regional Water Quality Control Board sq ft square feet

SSSL site specific screening level

STLC soluble threshold limits concentrations

TRV Toxicity Reference Value

TTLC Total Threshold Limit Concentrations

U.S.C. United States Code

USDA Unites States Department of Agriculture

USFS United States Department of Agriculture Forest Service

USGS United States Geologic Survey v

EXECUTIVE SUMMARY

The Department of Interior, National Park Service (NPS) retained Environmental Cost Management, Inc. (ECM) to prepare an Engineering Evaluation/Cost Analysis (EE/CA) Report for the lead impacted surficial soil around the potable water tank at Devils Postpile National Monument (DEPO) in Madera County, California (Figure 1). NPS is engaging in a non-time critical removal action (NTCRA) process at DEPO, using their authority under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA).

In 2005, lead-based paint chips were released around a 100,000 gallons potable water tank located within DEPO boundaries, referred herein as “the Site”, during sandblasting maintenance activities performed as part of the lead abatement of old paint and repainting of the tank’s exterior. In 2008, Provost and Pritchard Consulting Group (P&P, 2008)1 conducted a preliminary assessment (PA) for potential lead impacts to surficial soil at the Site. NPS concluded that additional work was necessary to address lead contamination at the Site. In 2013, ECM reviewed the data from the PA report and prepared a Work Plan for Soil Sampling2 (Work Plan) to perform surficial soil sampling using incremental sampling methodology (ISM) to facilitate the preparation of an EE/CA Report for the Site. ECM implemented the Work Plan activities in July 2013 and the results are presented in Section 2.4 below in this EE/CA.

Using the additional collected data, ECM completed a streamlined risk assessment (Section 2.6) for human and ecological receptors that indicates a risk to ecological receptors from potential exposure to concentrations of lead in surficial soils exists at the Site. The hazard quotient (HQ) for potential exposure to lead impacted surficial soil at the Site is estimated at 0.64 for human health and 2.64 for ecological receptors. By definition, a HQ value of one or less is considered “safe” with regard to the effect of a chemical of potential concern (COPCs) to human health or the environment. Therefore, it is concluded that the lead impacted surficial soil at the Site poses a potential risk to the environment (ecological receptors), justifying a non-time critical removal action (NTCRA). ECM considered ecological soil screening benchmarks and area use factors in the refined streamlined risk assessment to calculate the Site Specific Screening Level of 193 mg/kg lead in soil (Section 2.6).

The scope of removal action evaluated in this EE/CA Report focuses on the following removal action objectives (RAO):

Prevent or reduce potential for human and ecological exposure (through inhalation, ingestion, and dermal contact) to lead in surficial soil; and, 1 Provost and Pritchard Engineering Group, Inc. Preliminary Assessment for the National Park Service, Devils

Postpile National Monument, prepared for Sequoia and Kings Canyon National Park, Three Rivers, California.

October 2008.

2 Environmental Cost Management, Inc., Work Plan for Soil Sampling Lead Impacted Soil near Potable Water Tank at Devils Postpile National Monument, Madera County, California. June 17, 2013.

vi

Prevent or reduce potential migration of lead impacted surficial soil via surface runoff, erosion, and wind dispersion.

Eight removal action technologies were reviewed (Section 4) to develop the following four removal action alternatives:

1. Alternative 1 – No action

2. Alternative 2 – Engineering and institutional controls (ICs)

3. Alternative 3 – Excavation and on-site consolidation with ICs

4. Alternative 4 – Excavation and off-site disposal

The four removal action alternatives were evaluated based on the following overall criteria (Section 5):

1) Effectiveness

a) Protectiveness

b) Level of treatment and/or containment

c) Reduction or elimination of contaminants of concern

2) Implementability

a) Technical feasibility

b) Administrative and legal feasibility

c) Ease of Implementation

3) Cost

a) Capital cost

b) Post removal site controls cost

c) Present worth value / present cost

d) Long-term operation, maintenance and monitoring (OM&M) costs

Effectiveness and implementability have been evaluated in detail in subsections presented for each alternative in Section 5. Figures 7, 8 and 9 illustrate Alternatives 2, 3 and 4, respectively, and Table 8 presents a comparative analysis for each of the four removal alternatives. The costs have been evaluated in detail and a complete break-out of estimated costs is provided in Attachment D.

Table 9 presents a summary for the recommended Alternative 4. Alternative 2 is the least protective and would leave the lead impacted soil exposed to the elements and to any humans or animals that can cross the proposed fence surrounding the Site. Alternative 3 would isolate and contain the lead impacted surficial soil in a Corrective Action Management Unit (CAMU), thus eliminating exposure to human and ecological receptors; however, CAMUs require ongoing OM&M to remain effective. Alternative 4, excavation and off-site disposal, will best meet the evaluation criteria for the Site. Alternative 4 is the most protective of human health and ecological receptors and is less costly than Alternative 2 and Alternative 3, both of which provide lower levels of protection and require long-term OM&M commitments.

1.0 INTRODUCTION

On behalf of the Department of the Interior, National Park Service (NPS), Environmental Cost Management, Inc. (ECM) prepared this Engineering Evaluation/Cost Analysis (EE/CA) Report for the Devils Postpile National Monument (DEPO) in Madera County, California (Figure 1).

This EE/CA Report addresses lead-based paint debris released during maintenance activities in 2005 at the potable water tank, referred herein as “the Site”, located within DEPO park boundaries.

Figure 1: Site Vicinity Map

1.1 AUTHORITY

This EE/CA Report has been prepared in accordance with the criteria established under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as well as sections of the National Oil and Hazardous Substances Pollution Contingency Plan (NCP) as applicable to removal actions (40 Code of Federal Regulations [CFR] §300.415 [b][4][I]). NPS has been delegated CERCLA lead agency authority by the President of the United States and the Secretary of the Interior, and is exercising this authority at the Site. This EE/CA is consistent with the United States Environmental Protection Agency (EPA) Guidance on Conducting Non-Time-Critical Removal Actions under CERCLA, EPA/540-R-93-057, Publication 9360.0.32, PB93-963402, August 1993.

1.2 PURPOSE AND OBJECTIVES

This EE/CA provides an engineering evaluation to support the selection of a Non-Time-Critical Removal Action (NTCRA) for the Site. Environmental investigations at the Site have identified conditions that correspond to factors in Section 300.415(b)(2) of NCP (40 C.F.R. 300.415).

These conditions indicate that a NTCRA may be necessary to abate, prevent, minimize, stabilize, mitigate, or eliminate threats to human health and the environment.

National Oil and Hazardous Substance Pollution Contingency Plan (NCP) discusses three types of removal actions: emergency, time critical, and non-time-critical. These designations are based on the urgency with which cleanup must be initiated to respond to a threat to human health and the environment posed by a release or potential release of hazardous substances.

Emergency and time-critical removal actions are initiated to respond to a release or potential release where less than six months are available for planning the response. A NTCRA may be implemented at DEPO potable water tank site, because the Preliminary Assessment3 indicated that no immediate threat to human health or the environment exists at the Site, therefore NPS determined that more than six months are available for planning a response for the identified release.

An Approval Memorandum (Attachment A) authorized the preparation of this EE/CA Report.

The Approval Memorandum is the first step in NTCRA process. Section 300.415(b)(4)(I) of NCP requires the development of an EE/CA with a public comment period, prior to the signing of the Action Memorandum to initiate the selected alternative for NTCRA.

The EE/CA identifies removal action objectives for protection of human health and the environment, identifies removal action alternatives, and assesses the effectiveness, implementability, and cost of the alternatives that satisfy the removal action objectives.

The EE/CA considers the nature of the contamination, any potential risks to human health and the environment, and how the alternatives fit into the strategy for Site remediation.

The goals of the EE/CA include:

Conduct a Streamlined Risk Assessment to determine the potential threats posed by contamination originating from the Site;

Prepare an EE/CA Report to propose removal action to address contamination;

Provide a framework for the evaluation and selection of potential response actions and applicable technologies consistent with the NCP and EPA Guidance.

1.3 BACKGROUND/SITE HISTORY

In 2008, P&P4 conducted a Preliminary Assessment (PA) of a historical release of lead-based paint chips and sandblasting debris at the 100,000-gallon aboveground potable water tank at DEPO. The tank site is located on a slope north of the campground (Figure 2). NPS reviewed all available site information and concluded that PA did not completely characterize the nature

3 Provost and Pritchard Engineering Group, Inc. Preliminary Assessment for the National Park Service, Devils

Postpile National Monument, prepared for Sequoia and Kings Canyon National Park, Three Rivers, California.

October 2008.

4 Ibid.

and extent of lead contamination at the Site. In 2013, ECM reviewed the data from PA report and prepared a Work Plan for Soil Sampling5 (Work Plan) to perform surficial soil sampling using incremental sampling methodology (ISM) to facilitate the preparation of an EE/CA for the Site. ECM implemented the Work Plan activities in July 2013 (Section 2.4 below).

Figure 2: Site Features

2.0 SITE CHARACTERIZATION

This section gives a general site description and an overview of site investigations that have been completed to characterize the nature and extent of lead impact to soils at the Site.

2.1 SITE DESCRIPTION

Located on the western slope of the Sierra Nevada range, between 7,200 and 8,200 feet above mean sea level, DEPO contains an interesting assemblage of flora, fauna and geology, for which the monument was set aside. The highlight of the monument is a sheer wall of

5 Environmental Cost Management, Inc., Work Plan for Soil Sampling Lead Impacted Soil near Potable Water Tank at Devils Postpile National Monument, Madera County, California. June 17, 2013.

symmetrical basaltic columns more than 60 feet high. The formation is a remnant of a basalt flow worn smooth on top by glacial erosion.

DEPO is located along the Middle Fork of the San Joaquin River, which drops more than 100 feet at Rainbow Falls, located two miles by trail from the Devils Postpile formation. DEPO covers approximately 798 acres administered under the jurisdiction of NPS. The Ansel Adams Wilderness encompasses 687 acres and 85 percent of DEPO, and the monument provides a portal to High Sierra backcountry.

DEPO is located in northeastern Madera County and closely borders Mono County, California.

The monument is located approximately two miles southwest of Mammoth Mountain ski resort at 119.0847 W Longitude and 37.629 N Latitude. DEPO features a ranger station, a 21-site campground, and 5.3 miles of established trails.

The closest community to DEPO is Mammoth Lakes, located nine miles to the east in Mono County. Other nearby communities along Highway 395 include Bishop, Crowley’s Lake, June, Lake, and Lee Vining. Access to DEPO from Lee Vining is 25 miles on Highway 395 to State Route 203.

The monument also protects several historic and prehistoric archeological and cultural sites.

These consist of trade and travel routes, ancient living and activity areas, evidence of herding and other uses and remains of early federal land management activities. The monument encompasses part of the ancestral homelands of several American Indian tribes and groups from both the east and west sides of the Sierra Nevada. The majority of the Devils Postpile archeological sites likely represent seasonal American Indian use. Ten of the eleven sites contain debris from manufacturing flaked stone tools or tool blanks. Interestingly, at least seven of these sites have basalt as well as obsidian waste flakes, possibly a sign of quarrying from the exposed basalt outcroppings. One site contains what appears to be a cache of stone tool blanks, artifacts which likely represent the important trans-Sierran trade of toolstone obsidian.

No food procurement or processing features have been documented.

NPS initiated tribal outreach during the monuments GMP to tribes in Madera, Mono, and Inyo Counties. For this project NPS sent letters to Benton Paiute Reservation, Big Pine Paiute Tribe, Bishop Paiute Indian, Reservation, Bridgeport Paiute Indian Colony, Fort Independence Indian Reservation, Lone Pine Paiute-Shoshone Indian Reservation, Mono Lake Kutzadika’a Paiute Indian Community, North Fork Mono Tribe, and North Fork Rancheria of Mono Indians.

2.1.1 Geology and Geohydrology

DEPO is located high on the western slope of the Sierra Nevada in eastern California. The Sierra Nevada is the largest single mountain range in the contiguous United States and is bounded on the west by California's Central Valley and on the east by the Basin and Range Province. Physiographically, the Sierra Nevada is a section of the Cascade-Sierra Mountains province, which in turn is part of the larger Pacific Mountain System physiographic division. The core of this north-northwest trending range is an enormous intrusion of granitic rock, the Sierra

Nevada batholith6. Within the monument, there are both extensive outcrops of granite and volcanic rock including basalts and dacites.

Geology/Geologic History

DEPO sits in the heart of the Sierra Nevada - the “snowy mountain range”- of California. The Devils Postpile and surrounding landscape gained early recognition as an excellent example of the volcanic and glacial processes that shaped the Sierra Nevada. In the early 1900s, observers including University of California Professor Joseph N. LeConte and U.S. Forest Service engineer Walter Huber recognized the significance of Devils Postpile as a “wonderful natural curiosity”7, warranting future scientific study that ultimately led to the establishment of the monument in 1911.

Although the geology of the monument is integrally linked to that of the Sierra Nevada, it exhibits locally-distinct features, which are evidence of the monument’s unusual geologic history within the range. These distinct geologic features include the Devils Postpile, Rainbow Falls, granitic domes, and other evidence of volcanism.

The Devils Postpile geologic feature is a small part of a single lava flow which cooled in a way that promoted column formation. Columns would have started forming at the flow surface and extended progressively inward as the interior cooled and solidified over about two decades.

The formation as we see it today was exposed by the scouring action of glaciers plucking into the hardened flow to reveal the buried columns, unveiling a polished mosaic of polygons on the surface and majestic columns as the glacier melted away. Glaciers are also responsible for the brilliant polish and dome shape that makes the Devils Postpile so unique among the world’s other outcroppings of columnar rock.

Analyses and interpretation of the data to determine the age of the Postpile have evolved over time. The most recent studies, which used more precise Argon isotope techniques, found that the Postpile formed about 82,000 years ago8. This date places the Postpile flow within an interglacial period between the Tahoe and Tioga glaciations as suggested by many, including Huber and Eckhardt9.

Most columnar rock formations around the world occur in basaltic or andesitic rock, though the process of columnar jointing can occur in other mediums besides lava such as mud, saltpans, and frost. Understanding of the actual type of lava that formed the Devils Postpile has changed in recent years. Traditionally the rock which forms the Devils Postpile has been referred to as

6 USGS, “Geology in the Parks – Geology and Geophysics - Sierra Nevada”, last updated 01/13/04, accessed

05/29/2013. geomaps.wr.usgs.gov/parks/province/pacifmt.html.

7 LeConte, J.N. Letter to President Wm. H. Taft, Berkeley Water Resources Library, Walter Huber Papers. March 29, 1911.

8 Mahood, G., J. Ring, S. Manganelli and M. McWilliams. New 40Ar/39Ar Ages Reveal Contemporaneous Mafic and Silicic Eruptions During the Past 160,000 Years at Mammoth Mountain and Long Valley Caldera, California.

Geological Society of America Bulletin 122(3-4): 396. 2010.

9 Huber, N. K. and W. W. Eckhardt. The Story of Devils Postpile: A Land of Volcanic Fire, Glacial Ice, and an Ancient River. The Sequoia Natural History Association, Three Rivers, CA. 2001.

basalt10,11,12. Recently, classification has been refined and the formal petrologic name is basaltic trachyandesite. Today, for general references the geologic units of the monument are referred to as basalt, dacite, and andesite

The exposed columns of the Postpile formation are the most spectacular and symmetrical attributes of a larger sheet of basaltic lava that evidences glaciation, evidencing the combined artistry of “Fire and Ice working together in the making of beauty” (John Muir). This glacially eroded sheet of silicon rich lava (53.9 - 54.4% SiO2) is preserved discontinuously along the floor of the Middle Fork San Joaquin River canyon in two major remnants and several small ones, distributed for 4.3 miles downstream from near Upper Soda Springs Campground. The eroded scoria cone and dikes opposite the modern day campground represent the eroded vent of an older crystal-poor lava flow that erupted about 121,000 years ago. This flow directly underlies the crystal-rich Postpile basalt, and both flows can be observed along the trail above the river's west bank. Despite wide search, the vent for the Postpile basalt has not been found13.

The crown jewel of the lava flow is the Postpile formation that reveals the interior of the lava flow with columns rising above a remarkable field of postglacial talus of fallen columns totaling 196 feet in depth above the contact zone of lava and granite at the river. The highpoint of the lava flow is 1,700 feet east, just outside the monument boundary for a total estimated depth of the flow at 360 feet.

The lava is widely striated and plucked, eroded into knolls, ridges, and sidewall benches;

surviving exposures are nearly all massive and have only sparse scattered vesicles. Slender columns at the iconic Postpile rise to 60 feet high, polygonal, typically 2 to 3.5 feet thick, and variously vertical, curved, inclined, or subhorizontal14; elsewhere in the unit sets of stouter or less regular columns are widespread, but hackly and block jointing is common too.

One aspect of the Devils Postpile that sets it apart from the other columnar formations is the presence of glacial polish and glacial striations. Such features exhibit the power of glaciers to erode rock and thus the exact mechanism by which the columns of the Postpile were revealed.

Another dramatic factor is the erosion of the San Joaquin River downstream from the Postpile, that helped to cut the gorge showcasing dramatic basalt columns plunging into the river on the east bank contrasted with the granite wall on the west bank.

Soil quality and productivity depend on climate, inherent soil type, and soil condition. High elevation restricts the growing season and maintains cold soil temperatures for most of the year

10 LeConte, J. N. The Devil’s Postpile. Sierra Club Bulletin, (8):170-173. 1912.

11 Dalrymple, G. B. Potassium-Argon Dates of Three Pleistocene Interglacial Basalt Flows from the Sierra Nevada, California. Geologic Society of America Bulletin 75(8): 753-758. 1964.

12 Clow, D. W. and K. R. Collum. Geology of the Volcanic Rocks at Devils Postpile, California. Journal of Natural Sciences 1: 18-21. 1986.

13 Hildreth, W. and J. Fierstein. Eruptive History of Mammoth Mountain and Its Mafic Periphery, California: USGS Professional Paper; 250 ms. pp., 43 Figures, 3 Tables; Appendices; geologic map scale 1:24,000. 2014.

14 Huber, N.K. and C. D. Rinehart. Geologic Map of the Devils Postpile Quadrangle, Sierra Nevada, California:

USGS Map GQ-437; scale 1:62,500. 1965.

in all but the southern, lower elevation areas. This limits the activity of plants, burrowing animals, soil insects, and microorganisms. Essential plant nutrients, such as nitrogen, phosphorus, potassium, calcium, and magnesium are severely limited15.

It is difficult to locate an area within the 798 acres of DEPO that is not covered by pumice. The pumice within the monument indicates post-glacial volcanic activity from the chain of craters to the NE from the Inyo Craters to Mono Craters. The pumice at the monument plays an important role in the area's phytogeography and vegetation development. Most of the pumice found in the monument is less than 0.4 inches in diameter suggesting that it traveled some distance before falling. The Inyo Craters eruptions in 1350 Common Era (CE) are considered the source of the monument’s pumice16. Three vents were active, all fed by a common rhyolite dike. The combined thickness of these layers can extend up to 3 feet deep. In most areas of the monument it is less than six inches in depth. In flatter areas (meadow areas and "tables") the pumice accumulation averages near 0.5 to 1.5 feet deep. Little soil formation probably occurred before the present pumice cover appeared, probably due to the facts that:

1) glaciated volcanic rock-surfaces are very slow to decompose;

2) slopes did not allow particle accumulation;

3) montane and sub-alpine climates do not foster rapid development of pioneer plant communities; and

4) snowpack and rainfall contribute to rapid soil erosion.

Primary parent material at the Site include areas of volcanics, including andesite, basalt, and rhyolite, and pyroclastic deposits. Andesitic tuffs, ash, and pumice soils were observed near the tank during ECM’s site reconnaissance. Most of the high elevation meadows are rich in volcanic ash. Soils formed in tephra and ash tend to be richer in nutrients and organic matter, but when exposed can also be exceptionally dusty.

The technical description, based on a general Natural Resource Conservation Service mapping effort in 199517, most soils in the monument are classified as vitrandic xerochrepts, typic cryorthents and rocky outcrops. These soils are typically coarse, sandy and very well to excessively drained and are predominately rocky and dry (xeric).

15 USDA, Forest Service, Final Wilderness Plan and Environmental Impact Statement, Inyo and Sierra National

Forests, John Muir/Ansel Adams and Dinkey Lakes, July, 2012.

16 Millar, C.I., J. C. King, R. D. Westfall, H. A. Alden, D. L. Delany. Late Holocene Forest Dynamics, Volcanism, and Climate Change at Whitewing Mountain and San Joaquin Ridge, Mono County, Sierra Nevada, CA, USA. Volume 66, Issue 2, September 2006, Pages 273–287. 2006.

17 National Resource Conservation Service (NRCS). Soil Mapping of Devils Postpile National Monument. 1995.

Hydrology

The hydrological force of the Upper Middle Fork of the San Joaquin River and its tributaries is the dominant geomorphic process (and important resource) acting today in DEPO18 . This river flows within the monument from north to south near the eastern boundary. In the northern portion of the monument, it meanders through meadows, then begins to descend more rapidly in the southern portion and includes scattered pools, quickly flowing rapids, cascades, and the 101 foot high Rainbow Falls.

There is no long-term hydrology gauging station upstream of the monument on the Upper Middle Fork of the San Joaquin River19 . A recently-installed gage within the monument provides stream flow data from October 2009 through the present. During that period runoff peaked at 1,520 cubic feet per second on June 23, 2011, and reached its minimum of 7.5 cubic feet per second on September 21, 2013. For Sierra Nevada streams, the annual high water event typically occurs in late spring or early summer and is fed by seasonal snowmelt. High water events may also be caused by runoff from late summer thunderstorms. However, many of the highest magnitude floods occur during winter months due to rain on snowpack. The United States Geologic Survey (USGS) stream gaging station is important for detecting the change in seasonality of spring run-off, in addition to high/low/extreme discharge events.

As with other Sierra high-elevation rivers and streams, the majority of the Upper Middle Fork San Joaquin water originates as snow during the months of October through March each year20 . Accordingly, river runoff varies greatly throughout the year, with the greatest stream flow volume in warm summer months (59% of total annual flow in May through July), and next-greatest stream flow in early spring (29% of total annual flow in February through April)21 .

However, some of the highest flows occur in winter months from rain-on-snow events. There is no long term groundwater gauging for the monument. Instrumentation was installed in a new well in 2009 to begin data collection on groundwater.

As one of the twelve primary rivers originating in the Sierra Nevada22, the San Joaquin River is one of California’s most important sources of water for human uses in the state23. It is part of the Sacramento-San Joaquin River watershed, which is under jurisdiction of California’s Central Valley Regional Water Quality Control Board.

18 Mutch, L. S., M. G. Rose, A. M. Heard, R. R. Cook and G. L. Entsminger. Sierra Nevada Network Vital Signs Monitoring Plan. DOI National Park Service, Fort Collins, CO. Natural Resources Report NPS/SIEN/NRR- 2008/072. 2008.

19 Andrews, E. D. Hydrology of the Sierra Nevada Network National Parks: Status and Trends. Natural Resource Report NPS/SIEN/NRR—2012/500. National Park Service. Fort Collins, CO. 2012.

20 Kattlemann, R. Hydrology and Water Resources. In Sierra Nevada Ecosystem Project: Final Report to Congress, vol. III. University of California, Centers for Water and Wildland Resources. Davis, CA. 1996.

21 Cayan, D.R. and L.G. Riddle. A Multi-basin Seasonal Streamflow Model for the Sierra Nevada. In Proceedings of the Ninth Pacific Climate Workshop, edited by K.T. Redmond and V.L. Tharp. 141-52. 1993.

22 Mount, J. California Rivers and Streams. University of California Press. Berkeley, CA. 1997.

23 California Department of Water Resources. Interagency Ecological Studies Program. Sacramento, CA 2009.

2.1.2 Climate, Vegetation and Wildlife

Climate within DEPO varies greatly by season. During the months of September and October, daytime temperatures can range from the mid-70’s to mid-80’s degree Fahrenheit (°F), and evening temperatures can drop into the low 30’s and 40’s °F. Winter day and evening temperatures often remain below freezing for extended periods of time. Precipitation usually occurs year round with sub-tropical thunderstorms in the spring and autumn and significant rain and snow events in the winter. Average rainfall is about 30 inches per year. Snowfall typically exceeds 400 inches per year24.

The Inyo National Forest surrounds DEPO and 85% of the Monument are included within the Ansel Adams Wilderness. DEPO's vegetation is a montane forest dominated by red fir and lodgepole pine of the east slope of the Sierra Nevada. Though technically a west slope location, the monument's proximity to both west and east sides of the Sierra Nevada results in biological communities that have east-slope as well as west-slope affinities25. Western slope flora includes mountain hemlock, red fir, alder, and gooseberry.

Recent plant inventories documented 380 plant species in the monument. Along the San Joaquin River and the few creeks that flow into it, typical montane riparian vegetation can be found, such as quaking aspen, black cottonwood, alder, and willows. Both wet and dry meadows dot the monument, and during the spring and early summer when water is available, wildflowers such as cinquefoil and alpine shooting star can be found.

The unique geography of the area fosters relatively high species diversity concentrated in a small area. The Monument contains animals such as black bears, mule deer, and coyotes.

Soda Springs Meadow, near the Ranger Station, harbors an abundance of songbirds. Dark-eyed juncos and white-crowned sparrows are common in the summer. The talus at the base of Devils Postpile is home to many squirrels and chipmunks and the pine martens, which hunt them. Another asset in terms of biodiversity is the burned area near Rainbow Falls, which is habitat for many plants and animals that will not live in heavily forested areas.

A total of 135 plant species in the Sierra Nevada have status as Threatened, Endangered, or Sensitive. Plants that are federal species of concern (former Category 2 species) under the Federal Endangered Species Act include:

1. Three-bracted Onion,

2. Yosemite Woolly Sunflower,

3. Congdon's Lomatium,

4. Tiehm's Rock-cress,

5. Slender-stemmed Monkeyflower, and

6. Bolander's Clover.

24 National Park Service, www.nps.gov/depo/naturescience, accessed 05/29/2013.

25 Ibid.

None of these plants are found at or near the Site (see Table C-1 of Attachment C for a list a species in DEPO provided by NPS).

Although Category 2 was abolished in 1996, species of concern is an informal term that refers to those species that might be declining or be in need of concentrated conservation actions to prevent decline. Therefore, these six species continue to be evaluated and managed by NPS.

Four state-listed rare plant species are considered restricted and limited throughout all or a significant portion of their range, and may represent disjunct populations at the extreme end of their range:

1. Yosemite Onion,

2. Tompkin's Sedge,

3. Congdon's Woolly Sunflower, and

4. Congdon's Lewisia.

None of these plants are found at or near the Site (see Table C-1 of Attachment C for a list a species in DEPO provided by NPS).Endangered or threatened species of animals that occur in the Sierra Nevada include:

1. Sierra Nevada Bighorn Sheep

2. California Condor

3. Southwestern Willow Flycatcher

4. Paiute Cutthroat Trout

5. Lahontan Cutthroat Trout

6. Owens Tui chub

None of these animals are found at or near the Site (see Table C-1 of Attachment C for a list a species in DEPO provided by NPS).

Sierra Nevada mid and high elevations provide the only habitat for the Sierra Nevada mountain yellow-legged frog, the Yosemite toad, and the Sierra Nevada bighorn sheep

2.1.3 Land Uses

DEPO hosted 87,845 visitors in 2012, with an average of 103,25826 visitors annually from 2009 to 201227. Recreational activities vary with the season and include wildflower and wildlife viewing, sightseeing and photography, hiking, horseback riding, camping, fishing, skiing, and snowshoeing28 and 85 percent of DEPO is wilderness. Some NPS employees live within DEPO during the open season (April/May to October/November) and a small residential area exists within the park. The Site addressed by this EE/CA only encompasses the 25 feet around the

26 National Park Service, “Devils Postpile Park Statistics”, accessed 01/27/2014, www.nps.gov/depo/parkmgmt 27 Ibid.

28 National Park Service, “Devils Postpile Outdoor Activities”, accessed 01/27/2014, www.nps.gov/depo/planyourvisit/outdooractivities.htm potable water tank and only employees access the area during routine park maintenance activities.

2.2 SITE HISTORY

The Devils Postpile feature was known locally in the 1890’s as the Devils Woodpile. It was first documented as the Devils Postpile in 1901 on various maps. The Postpile was part of Yosemite National Park in the late 1800’s, when Congress designated its boundaries. Congress removed 500 square miles, including DEPO, from Yosemite National Park in 1905 under pressure from mining and lumber lobbying interests. By 1910, a proposal was made to dynamite the Postpile and use it to dam the San Joaquin River. Members of the Sierra Club and University of California professor Joseph LeConte, who was also a mountaineer, successfully campaigned against the project.29.

On July 6, 1911, President William Howard Taft proclaimed the area a national monument and extended full protection of the federal government to the Devils Postpile formation and Rainbow Falls. The monument was originally administered by the United States Department of Agriculture Forest Service (USFS), and then transferred to the national park system in 1934.

After the transfer, DEPO was first managed by Yosemite and then by Sequoia and Kings Canyon National Parks before becoming an independent unit of NPS. Congress also included 747 acres of the monument in the Ansel Adams Wilderness in 1984; consequently, 85 percent of the monument is designated as wilderness.

NPS oversees the 687-acre Devils Postpile National Monument, while the USFS manages the lands surrounding the monument. Together these two federal agencies work as partners to manage public lands in this area. In 2009, USFS and NPS entered into a Memorandum of Understanding (MOU) to collaborate on the preparation of the Devils Postpile National Monument General Management Plan (GMP) and create a foundation for future cooperation in management and planning. Under the MOU, USFS and DEPO are key participants in the development of desired valley-wide conditions for facilities, transportation, and the overall visitor experience, as well as resource management issues30.

2.2.1 Water Tank Operational History

The lead-impacted soils addressed in this EE/CA surround an aboveground steel tank that is the sole potable water storage facility for DEPO31. The 100,000-gallon tank was installed in

29 Sherpa Guides, Grossi, Mark, “Longstreet Highroad Guide to the California Sierra Nevada – Devils Postpile

National Monument”, www.sherpaguides.com/california/mountains/eastern_sierra/devils_postpile_national_monument.html.

30 National Park Service, Devils Postpile National Monument General Management Plan. Preliminary Alternatives.

Newsletter #3, Summer 2011.

31 Provost and Pritchard Engineering Group, Inc., Preliminary Assessment for the National Park Service, Devils Postpile National Monument, prepared for Sequoia and Kings Canyon National Park, Three Rivers, California.

1964 and has been in seasonal use since its installation. The tank is drained at the end of each season in October and is refilled at the beginning of each spring season in May. The tank sits on a slope north of the campground in the northern part of the monument grounds. The campgrounds, ranger station, and facilities are located within 1,000 feet south and 125 feet in elevation below the tank site. The Site is accessible via a walking uphill trail from the campgrounds and an unpaved access road from the southeast. The site is designated as “employees only” and is generally not visible or accessible to visitors.

By 2005, the tank’s outer surface had weathered to the point that the original paint was pealing and flaking. In September 2005, a painting contractor (AA-1 Services of Paramount, California) was retained to remove the lead based paint and recoat the exterior of the water tank. The contractor constructed a negative pressure containment system by wrapping scaffolding surrounding the tank with a plastic material extending 5 feet from the external tank wall. After recoating operations were completed, Mr. John Fernandes, Maintenance Mechanic, noted that lead-based paint chips and sandblasting material had been left by the tank, accessible to the public and wildlife. The paint chips and blast material were not removed within 24 hours as required by contract, but remained on the ground for approximately two weeks.

2.3 SUMMARY OF PREVIOUS INVESTIGATIONS

In November 2005, due to a contract violation in which the painting contractor collected confirmation samples without oversight by NPS staff, DEPO Maintenance Mechanic John Fernandes collected soil samples at ten locations within the sand-blasting containment area to verify the cleanup procedures. The exact location from which these ten soil samples were collected is not mapped; however, notes included in the file and discussions with the supervisory ranger suggest that the samples were collected from within the footprint of the former containment area at approximately 15-foot centers32.

Laboratory results for samples collected by Mr. Fernandes in 2005 showed that:

Lead was present in all 10 samples collected above the method detection limit.

The average lead concentration was 1,049 mg/kg; sample-specific lead concentrations ranged from 20 mg/kg to 2,100 mg/kg. These concentrations of lead in site soils are below the California Human Health Screening Levels (CHHLS) of 3,500 mg/kg for commercial/industrial use.

The average lead concentrations slightly exceed the Total Threshold Limit Concentration (TTLC) of 1,000 mg/kg, as defined in Title 22, California Code of Regulations (CCR).

32 Provost and Pritchard Engineering Group, Inc., Preliminary Assessment for the National Park Service, Devils

Postpile National Monument, prepared for Sequoia and Kings Canyon National Park, Three Rivers, California.

The concentrations also exceed the EPA regional screening levels (RSLs) for soil (400 mg/kg [residential] and 800 mg/kg [industrial]).

In 2008 P&P33 conducted a PA in general accordance with CERCLA guidance manual for the 2005 release of lead-based paint chips and sandblasting debris at the Site. The objective of PA was to identify past and present practices related to the historic release and to evaluate the Site’s Hazard Ranking System Score.

The scope of the investigation included review of available records, a site reconnaissance and interviews with DEPO personnel. The investigation focused on the 2005 water tank sandblasting operation activities intended to remove the lead-based paint from the exterior of the tank.

The PA resulted in the following findings:

The primary type of waste generated on-site was a one-time release of lead-based paint chips related to the sandblasting operations for external tank cleaning in preparation for recoating. Some amount of the blasting material was also released to the soil during the blasting operations; however, the sandblasting (quartz sand) material is not considered a human health or environmental hazard.

Based on the PA, groundwater and surface water targets are not within sufficient distance of the Site for there to be a migratory pathway to these resources. Restrictive air flow due to the hilly forested terrain between the source and potential targets make it unlikely that an airborne pathway exists. However, if soils were to be excavated in the future, the quantity of hazardous substances should be identified.

2.4 2013 EE/CA FIELD INVESTIGATIONS

The specific locations of the samples collected in 2005 are unknown, and therefore the extent of contamination undetermined, which represented a gap in Site characterization. The exceedances of RSLs for lead at the Site indicate that additional information was necessary to determine background concentrations for comparison and, if appropriate, to develop proposed action levels for the Site. To address gaps in the characterization of contamination and to develop and evaluate removal action alternatives in accordance with CERCLA, NPS issued an EE/CA Approval Memorandum on October 11, 2012.

ECM prepared a Work Plan34, including a Sampling and Analysis Plan (SAP) and Quality Assurance Project Plan35 (QAPP) to address the remaining data need for Site characterization.

In July 2013, ECM collected additional Site data to characterize the nature and extent of

33 Ibid.

34 ECM, 2013. Work Plan for Soil Sampling, Lead Impacted Soil Near Potable Water Tank at Devils Postpile National Monument, Madera County, CA. July 17.

35 ECM, 2013. Sampling and Analysis Plan and Quality Assurance Project Plan for Site Characterization near Potable Water Tank Devils Postpile National Monument, Madera County, California. July 17.

potential lead contamination in surface soils near the potable water tank. ECM used ISM to characterize the naturally occurring background lead concentrations and the nature and extent of lead contamination at the Site in three intervals (decision units) to 25 feet from the tank.

Beyond 25 feet from the tank, bedrock outcrops create a natural topographic boundary. Surface soil is not available on rock outcrops. ISM provides a representative and reproducible estimate of the mean concentration of analytes in a specific area of interest, known as a decision unit (DU). ECM collected samples from the following approximate decision units at the Site (Figure 3):

1. DU-1: Surface soils within 5 feet of the water tank footing;

2. DU-2: Surface soils between 5 feet and 15 feet from the water tank footing;

3. DU-3: Surface soils between 15 feet and 25 feet from the water tank footing; and,

4. DU-4: Background surface soils at approximately 150 feet upgradient (north-northwest) from the water tank footing.

ECM used ISM to collect 4 aggregate soil samples for each DU, each sample consisting of 30 incremental subsamples collected across each DU, to characterize each DU at the Site. A total of four multi-increment (MI) samples were collected at each decision unit per the Work Plan and SAP/QAPP. As required by NPS, one additional QA/QC sample was collected at DU-1 (DEPO- DP-100) with a reported lead concentration of 490 mg/kg, which is consistent with results from other samples collected in DU-1.

Figure 3: Decision Unit Layout

MI soil samples were analyzed for total lead content by a California certified laboratory using EPA method 6010B. Additionally, the sample with the highest reported lead concentration (DEPO-01-102) was analyzed for soluble threshold limits concentrations (STLC) Citrate (citric acid) and DI (deionized water). A summary of laboratory results for samples collected by ECM in July 2013 showed that:

Lead was present in all 16 MI samples collected above the method detection limit.

Average lead concentration at DU-1 was 507.5 mg/kg; sample-specific lead concentrations at DU-1 ranged from 400 mg/kg to 650 mg/kg. STLC Citrate and DI for sample DEPO-01-102, with a reported total lead concentration of 650 mg/kg, were reported as 40 B36 milligrams per liter (mg/L) and 0.088 J37 B mg/L, respectively.

Average lead concentration at DU-2 was 177.5 mg/kg; sample-specific lead concentrations at DU-2 ranged from 120 mg/kg to 240 mg/kg.

Average lead concentration at DU-3 was 68.3 mg/kg; sample-specific lead concentrations at DU-3 ranged from 61 mg/kg to 80 mg/kg.

Average lead concentration at DU-4 (background) was 4.9 mg/kg; sample-specific lead concentrations at DU-4 ranged from 4.30 mg/kg to 5.50 mg/kg.

Concentrations of lead in surface soils at DU-1, DU-2 and DU-3 exceeded background concentration of 5.55 mg/kg (95% Student’s upper confidence limit [UCL]) estimated from samples collected at DU-4.

Laboratory reports for samples collected in July 2013 are presented in Attachment B and Attachment C, Tables C-3a, C-3b, and C-3c summarize these results.

2.4.1 Site-Specific Background Data

Under CERCLA38, concentrations of contaminants of concern below the naturally occurring background levels are not generally subject to removal action. A Site Specific Background concentration for lead in surface soils, determined within the 95 percent upper confidence limit (95% UCL) using a Student’s distribution curve, was estimated at 5.55 mg/kg from laboratory results of four MI samples collected at DU-4 in July 2013 (Table C-2).

2.5 NATURE AND EXTENT OF CONTAMINATION

Surface soils surrounding the potable water tank, extending to at least 25 feet from the tank footing; indicate surface soil lead concentrations exceed background lead concentrations.

These data indicate lead from the tank’s lead-based paint coating migrated to surrounding soils.

Lead concentrations decrease exponentially (power trendline) with distance from the tank footing (Figure 4).

36 Compound was found in the blank and sample.

37 Result is less than the reporting limit (RL) but greater than or…