Exhibit_D_Appendix_D-17_NMED_SSG.pdf

~ LosAlamos

NATIONAL LABORATORY

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Associate Directorate for Environmental Manage,!!:!!]!t,,, P.O. Box 1663, MS M992 Los Alamos, New Mexico 87545

(505) 606-2337

John Kieling, Bureau Chief Hazardous Waste Bureau New Mexico Environment Deparhnent 2905 Rodeo Park Drive East, Building 1 Santa Fe, NM 87505-6303

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Environmental Management P. 0. Box 1663, MS M984 Los Alamos, New Mexico 87545

(505) 665-5658/FAX (505) 606-2132

Date: MAR 2 8 2018 Refer To: ADEM-18-0032

LAUR: 18-22418

Subject: Screening-Level Ecological Risk Assessment Methods, Revision 5.1

Dear Mr. Kieling:

Enclosed please find two hard copies with electronic files of the Screening-Level Ecological Risk Assessment Methods, Revision 5 .1. This document was revised to incorporate comments received from the New Mexico Environment Department (NMED) on January 19, 2018. Pursuant to Section XXIII.E of the 2016 Compliance Order on Consent, the U.S. Department of Energy and Los Alamos National Security, LLC conducted informal discussions with NMED and submitted proposed changes on March 5, 2018. An explanation for the use of the referenced body weight for the desert cottontail was also provided to NMED on March 15, 2018. Revision 5.1 of this document includes the changes discussed and reviewed by NMED. The changes include updates to reference callouts and hyperlinks, and a table note that addresses the body weight used for the desert cottontail.

If you have any questions, please contact Kent Rich at (505) 665-4272 (krich@lanl.gov) or Arturo Duran at (505) 665-7772 (arturo.duran@em.doe.gov).

Sincerely, £eT~ Environmental Remediation Program Los Alamos National Laboratory

Sincerely, David S. Rhodes, Director Office of Quality and Regulatory Compliance Environmental Management Los Alamos Field Office

An Equal Opportunity Employer I Operated by Los Alamos National Security, LLC for the U.S. Department of Energy

ESHID-602965

John Kieling 2 ADEM-18-0032

ET/DR/KR:sm

Enclosures: Two hard copies with electronic files - Screening-Level Ecological Risk Assessment Methods, Revision 5.1 (EP2018-0053)

Cy: (w/enc.)

Arturo Duran, DOE-EM-LA Kent Rich, ADEM ER Program

Cy: (w/electronic enc.)

Laurie King, EPA Region 6, Dallas, TX Raymond Martinez, San Ildefonso Pueblo Dino Chavarria, Santa Clara Pueblo Steve Yanicak, NMED-DOE-OB, MS M894 emla.docs@em.doe.gov Public Reading Room (EPRR) ADESH Records PRS Database

Cy: (w/o enc./date-stamped letter emailed) lasomailbox@nnsa.doe.gov Peter Maggiore, DOE-NA-LA David Rhodes, DOE-EM-LA Enrique Torres, ADEM ER Program Randy Erickson, ADEM Jocelyn Buckley, ADESH-EPC-CP Mike Saladen, ADESH-EPC-CP Benjamine Roberts, ADESH-EPC-DO William Mairson, ADESH/P ADOPS Craig Leasure, P ADO PS

LA-UR-18-22418

April 2018

EP2018-0053

Screening-Level Ecological Risk Assessment Methods, Revision 5.1

Prepared by the Environmental Programs Directorate

Los Alamos National Laboratory (LANL), operated by Los Alamos National Security (LANS), LLC, for the U.S. Department of Energy under Contract No. DE-AC52-06NA25396, has prepared this document. The public may copy and use this document without charge, provided that this notice and any statement of authorship are reproduced on all copies.

Screening-Level Ecological Risk Assessment Methods, Revision 5.1 iii

EXECUTIVE SUMMARY

This document provides guidance to conduct screening-level ecological assessments at the Los Alamos National Laboratory (LANL or the Laboratory). This guidance promotes consistency, rigor, and defensibility in ecological screening assessments and in reporting the results. The purpose of the screening assessment is to provide information to the risk managers to make informed risk-management decisions. The information presented in this document has been updated to reflect the current approaches implemented since the last revision of the screening-level ecological assessment methods.

The Laboratory-wide information needed for the screening-level ecological risk problem formulation, including the environmental setting, contaminant fate and transport, exposure pathways, and food webs, is presented. Screening assessments are performed on solid waste management units (SWMUs) or areas of concern (AOCs); the area may also be a collection of SWMUs and/or AOCs in a consolidated unit or some other aggregate. In this document, the term site is used broadly to include these different possibilities.

The purpose of the screening evaluation is to identify chemicals of potential concern (COPCs) that should be retained as chemicals of potential ecological concern (COPECs). The screening evaluation focuses investigations on important ecological concerns of potentially contaminated sites and identifies those sites that do not have COPECs. Sites with no COPECs do not need further ecological evaluation. The outcome of the screening is protective of receptors from potential adverse ecological effects but is not intended to be predictive of ecological risk. Thus, protective assumptions are made throughout the screening evaluation to ensure contaminants, exposure pathways, and sensitive species are not missed.

The key components of the screening evaluation are the ecological screening levels (ESLs) that are developed for each chemical and receptor and are media-specific. This document presents the basis for, and the elements used in, calculating ESLs for the screening assessment. The ESLs are determined such that if a site has concentrations of a chemical above the ESL in any medium, the site warrants further consideration because the chemical concentration(s) may pose a potential risk to ecological receptors. To evaluate the potential risk for each COPC, the ESL and the site exposure point concentration are used to calculate a hazard quotient (HQ). If the HQ for a COPC at a site with only a single COPC is greater than 1 or the HQ for a COPC is greater than 0.3 for a site with multiple COPCs, then that COPC is identified as a COPEC. The HQs are calculated for each receptor/COPEC combination and are the ratio of a receptor’s exposure at the site to an acceptable effects level (i.e., the ESL).

Because ESLs are specific to each medium evaluated (soil, sediment, or water), they do not account for exposure to multiple media. The potential hazard posed by multiple chemicals is summed as a hazard index (HI) for each wildlife receptor. If the HI is greater than 1, then the site may pose an ecological risk.

This document also describes the uncertainty analysis that follows the COPEC identification and the key sources of uncertainty in the screening assessment. This analysis includes a more refined screening assessment using ESLs based on the low observed adverse effect level (LOAEL) rather than on the no observed adverse effect level (NOAEL). The LOAEL analysis is less conservative and is designed to provide a more realistic, but still protective, estimate of potential risk. The LOAEL analysis is based on the lowest-effect ecological screening levels (L-ESLs).

The ESL, L-ESL, HQ, and HI calculations require toxicity information, including toxicity reference values (TRVs), and knowledge of bioconcentration and bioaccumulation factors for all chemicals for all receptors and media. The Laboratory’s ECORISK Database provides the necessary information and supporting detailed documentation for TRVs, ESLs, L-ESLs, and related information. The database includes values for the TRVs used to develop ESLs and L-ESLs, information on other studies considered for TRVs, transfer and bioaccumulation factors, and exposure parameters for the representative receptor species.

v

CONTENTS

1.0 INTRODUCTION

2.0 GENERIC PROBLEM FORMULATION FOR ECOLOGICAL RISK-SCREENING

ASSESSMENTS

2.1 Environmental Setting

2.1.1 Geographic Setting

2.1.2 Climate

2.1.3 Geology and Soil

2.1.4 Hydrology

2.1.5 Biology

2.1.6 Wetlands

2.2 Contaminant Fate and Transport

2.2.1 Hydrologic Transport

2.2.2 Mass Wasting and Mass Deposition

2.2.3 Atmospheric Transport

2.3 Exposure Pathways

2.4 Functional Food Web

2.5 Assessment Endpoints

2.6 Screening Receptors

3.0 DERIVATION OF ESLs

3.1 Screening-Level Ecological Risk Calculation Overview

3.2 Types and Sources of Ecological Effects Information

3.3 Wildlife Exposure and Effects Evaluations

3.4 ESLs for Chemicals

3.4.1 Soil ESLs

3.4.2 Burrow Air ESLs (Volatile-Phase Contaminants Only)

3.4.3 Sediment ESLs

3.4.4 Water ESLs

3.5 Radionuclide ESLs

3.5.1 Radionuclide Dose Limits and Effects Calculations

3.5.2 Soil ESLs

3.5.3 Sediment ESLs

3.5.4 Water ESLs

4.0 SCREENING-LEVEL ECOLOGICAL RISK ASSESSMENT

4.1 Scoping Evaluation

4.1.1 Ecological Scoping Checklist

4.2 Screening Evaluation

4.3 Uncertainty Analysis

4.3.1 Development of AUFs

4.3.2 Exposure-Related Parameters

4.3.3 Toxicity-Related Parameters

4.3.4 L-ESL Analysis

4.3.5 Comparison with Previous Investigations

4.4 Risk Interpretation

5.0 REFERENCES

vi

Figures

Figure 2.1-1 Laboratory TAs in relation to surrounding landholdings

Figure 2.1-2 Topography of the Los Alamos area

Figure 2.2-1 Key transport pathways

Figure 2.4-1 Terrestrial food web based on feeding relationships of biota on the Pajarito Plateau

Figure 2.4-2 Aquatic food web based on feeding relationships of biota on the Pajarito Plateau

Figure 2.6-1 Screening receptors for terrestrial food web

Figure 2.6-2 Screening receptors for aquatic food web

Figure 3.4-1 Ecological conceptual site model (CSM) for soil pathways

Figure 3.4-2 Aquatic CSM for sediment pathways

Figure 3.4-3 Terrestrial CSM for sediment pathways

Figure 3.4-4 Aquatic CSM for water pathways

Figure 3.4-5 Terrestrial CSM for water pathways

Figure 3.5-1 Aquatic CSM for sediment pathways

Figure 3.5-2 Aquatic CSM for water pathways

Figure 4.1-1 Terrestrial receptor conceptual exposure and transport model

Figure 4.1-2 Aquatic receptor conceptual exposure and transport model

Tables

Table 2.1-1 Sensitive Species Occurring or Potentially Occurring at the Laboratory

Table 2.6-1 List of Receptors Selected for Screening at the Laboratory

Table 3.3-1 Measures Required for the Wildlife Exposure Model

Table 3.4-1 Ecological Screening Receptors for Chemicals

Appendixes

Appendix A Derivation of Ecological Screening Levels

Appendix B Ecological Scoping Checklist

Plate

Plate 1 Vegetation land cover map of the LANL area vii

Acronyms

ACR acute-chronic ratio

ADEM Associate Directorate for Environmental Management

AOC area of concern

ARCS Assessment and Remediation of Contaminated Sediments asl above sea level

AUF area use factor

AWQC ambient water-quality criteria

BCF bioconcentration factor bgs below ground surface

BMP best management practice

Bq Becquerel

BW body weight

CCC criterion continuous concentration

CCME Canadian Council of Ministers of the Environment

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act

CMC criterion maximum concentration

COPC chemical of potential concern

COPEC chemical of potential ecological concern

CSL cleanup screening level

CSM conceptual site model

DCF dose conversion factor

DOE Department of Energy (U.S.)

EP Environmental Programs (Directorate)

EPA Environmental Protection Agency (U.S.)

EPC exposure point concentration

EqP equilibrium partitioning

ERM effect range median

ESA Endangered Species Act

ESH Environment, Health, and Safety (Directorate)

ESL ecological screening level

FSOC Federal Species of Concern

FSS Forest Service Sensitive Species

HI hazard index

HMP Habitat Management Plan

HQ hazard quotient

HR home range

IR inhalation rate viii

IAEA International Atomic Energy Agency

LANL Los Alamos National Laboratory

L-ESL lowest effect ESL

LOAEL lowest observed adverse effect level

LOEC lowest observed effect concentration

MC moisture content

MeV million electron volts

MPC maximum permissible concentration

NC negligible concentration

NCRP National Council on Radiation Protection

NMAC New Mexico Administrative Code

NME New Mexico Endangered

NMED New Mexico Environment Department

NMS New Mexico Sensitive Taxa

NMSOC New Mexico Species of Concern

NMT New Mexico Threatened

NOAA National Oceanic and Atmospheric Administration

NOAEL no observed adverse effect level

NOEC no observed effect concentration

PAUF population area use factor

PEC probable effect concentration

PTSE primary toxicity study evaluation

PTV primary toxicity value

RPF Records Processing Facility

S1 Heritage New Mexico: Critically Imperiled in New Mexico

SEL severe effect level

SI International System of Units

SLERA screening-level ecological risk assessment

SMDP scientific management decision point

SQS sediment quality standard

SQuiRT Screening Quick Reference Tables

Sv sievert

SWMU solid waste management unit

T&E threatened and endangered

TA technical area

TEC threshold effect concentration

TEL threshold effect level

TF transfer factor ix

TL threshold level

TRV toxicity reference value

UCL upper confidence limit

UET upper effects threshold

UF uncertainty factor

USACOE U.S. Army Corps of Engineers

VOC volatile organic compound

WQC water-quality criteria

1.0 INTRODUCTION

This revised methodology document describes the approach used by the Los Alamos National Laboratory (LANL or the Laboratory) Environmental Programs Directorate for screening-level assessments of potential impacts to ecological resources resulting from exposure to contaminants. The approach is consistent with the U.S. Environmental Protection Agency’s (EPA’s) “Ecological Risk Assessment Guidance for Superfund” (EPA 1997, 059370); the “Guidelines for Ecological Risk Assessment” (EPA 1998, 062809); “Issuance of Final Guidance: Ecological Risk Assessment and Risk Management Principles for Superfund Sites” (EPA 1999, 070086); and the “Guidance for Developing Ecological Soil Screening Levels” (EPA 2003, 085643). This guidance incorporates the assessment endpoints developed in “Generic Assessment Endpoints for Ecological Risk Assessment at the Los Alamos National Laboratory” (LANL 1999, 064137). The guidance in this document is consistent with the New Mexico Environment Department’s (NMED’s) “Risk Assessment Guidance for Site Investigations and Remediation” (NMED 2017, 602274; NMED 2017, 602273). The approach to ecological risk screening for radionuclides provided in this document is also consistent with the U.S. Department of Energy’s (DOE’s) “Graded Approach for Evaluating Radiation Doses to Aquatic and Terrestrial Biota” (DOE 2002, 085637) and DOE’s “RESRAD-BIOTA: A Tool for Implementing a Graded Approach to Biota Dose Evaluation, User’s Guide, Version 1” (DOE 2004, 085639). This version of the document incorporates guidance on and direction for conducting ecological risk-screening assessments and is consistent with risk-assessment conducted by the Laboratory.

EPA guidance requires that initial screening-level assessments use conservative assumptions to evaluate the potential for adverse ecological impacts. The rationale behind this requirement is to provide high confidence that all potential adverse impacts to ecological receptors resulting from exposure to contaminants are identified in the initial investigation. Thus, the screening-level assessment may be used to identify sites that clearly pose no threat to the environment as well as sites that need corrective action.

However, for the many sites that do not fall into one of these two categories, screening-level evaluations must be followed by a series of progressively more in-depth and site-specific evaluations to characterize risks accurately and to provide adequate information for risk-management decisions. The screening-level assessment helps to focus these more detailed (and often more complex) site-specific investigations by identifying important contaminants, receptors, ecological endpoints, and spatial scales. The screening-level evaluation also employs a common metric for comparing risks among different sites, thus providing a tool for prioritizing site investigations and corrective actions.

This document presents the ecological screening process for individual solid waste management units (SWMUs) or areas of concern (AOCs) as well as clusters of SWMUs and/or AOCs. Application of this methodology to larger spatial aggregates is not explicitly considered. The approach assesses present-day risk at the site where contamination has been investigated and characterized. However, these methods, coupled with the appropriate transport models, may be used to assess the potential for future ecological risk at areas affected by off-site transport of contaminants. The discussion and evaluation of transport models, other than to emphasize their importance, is beyond the scope of this document.

2.0 GENERIC PROBLEM FORMULATION FOR ECOLOGICAL RISK-SCREENING

ASSESSMENTS

As noted in the Comprehensive Environmental Response, Compensation, and Liability Act– (CERCLA- or Superfund-) specific ecological risk guidance (EPA 1997, 059370), problem formulation is the most critical step of an ecological risk assessment. The EPA guidance identifies (among others) the following issues for the screening-level problem formulation:

Environmental setting (physical and biological)

Contaminant fate and transport

Food webs

Screening receptors

Exposure pathways

Assessment endpoints

Therefore, problem formulation requires understanding the physical and biological setting of the Laboratory. The physical setting greatly influences the potential contaminant transport pathways, which also influence the potential exposure pathways for ecological receptors. The biological setting is important for receptor selection because receptors must represent the broad spectrum of plant and animal species present at the Laboratory. One key exposure pathway is expressed through the food web (section 2.4), which structures information on the feeding relationships among animals and plants to develop representative groups of ecological receptors. Receptor groupings based on feeding relationships are an efficient and effective way to represent all relevant biota. In the following sections, the general physical setting of the Laboratory and the surrounding area is summarized, followed by descriptions of the salient biotic features.

2.1 Environmental Setting

The Laboratory is situated on the Pajarito Plateau, which consists of a series of fingerlike mesas separated by deep east-to-west–oriented canyons cut by intermittent streams. Mesa tops range in elevation from approximately 2377 m (7800 ft) on the flanks of the Jemez Mountains to about 1890 m (6200 ft) at their eastern termination above the Rio Grande. The climate, geographic setting, geology, hydrology, and biology of the Laboratory are described briefly below.

2.1.1 Geographic Setting

The Laboratory and residential and commercial areas of Los Alamos and White Rock are located in Los Alamos County, in north-central New Mexico, approximately 60 mi northeast of Albuquerque and 20 mi northwest of Santa Fe. The surrounding land is largely undeveloped, with large tracts of land north, west, and south of the Laboratory held by the Santa Fe National Forest, Bureau of Land Management, Bandelier National Monument, General Services Administration, and Los Alamos County. The Pueblo of San Ildefonso borders the Laboratory to the east.

The Laboratory is divided into technical areas (TAs) that are used for building sites, experimental areas, waste disposal locations, roads, and utility rights-of-way (Figure 2.1-1). However, these uses account for only a small part of the total land area. Most land provides buffer areas for security and safety and is held in reserve for future use. Thus, much of the Laboratory is undeveloped land that supports diverse and abundant organisms. Land no longer needed to support programmatic activities may be transferred to

Los Alamos County or other government agencies. The TA boundaries shown in Figure 2.1-1 reflect current land transfer status.

Figure 2.1-1 Laboratory TAs in relation to surrounding landholdings

2.1.2 Climate

The average diurnal temperature at Los Alamos is 13°C (55°F). Winter temperatures range from −1°C to 10°C (30°F to 50°F) during the day, to −9°C to −4°C (15°F to 25°F) during the night. Summer temperatures range from 21°C to 31°C (70°F to 88°F) during the day to 10°C to 15°C (50°F to 59°F) during the night. The average annual precipitation (including both rain and water equivalent of frozen precipitation) is 48 cm (19 in.). Details are available at http://weather.lanl.gov/ and are discussed in the “Installation Work Plan for Environmental Restoration Project, Revision 8” (LANL 2000, 066802, p. 2-41).

The semiarid, temperate, mountain climate in Los Alamos County influences weather and soil development as well as biotic assimilation in the region. Both weather and soil conditions influence transport of contaminants at the Laboratory and potential exposure of ecological receptors to contamination. The speed, frequency, direction, and persistence of wind influence the airborne transport of contaminants. High winds, common in the spring, can result in atmospheric transport of contaminants.

The role of climate in the atmospheric contaminant pathway is considered part of the site-specific scoping evaluation.

Intense thunderstorms in the summer can cause erosion of unstable sediment or soil. The form, frequency, intensity, and evaporation potential of precipitation strongly influence surface water runoff and infiltration of contaminants. As discussed below, fires also change hydrological regimes, and small precipitation events may lead to large amounts of runoff.

2.1.3 Geology and Soil

Geologic and hydrologic information provides the basis for the discussion of hydrologic transport of contaminants. The likelihood of hydrologic transport is considered in the site-specific scoping evaluation (section 4.1). The geologic and hydrologic characteristics in and around the Laboratory as they relate to the potential for contaminant transport are complex. Additional literature on the hydrology and geology of the Los Alamos region may be found in an annotated bibliography of geologic, hydrogeologic, and environmental studies related to SWMUs and AOCs at the Laboratory (LANL 1990, 047588).

Geology

The Laboratory extends over the east-sloping dissected tableland of the Pajarito Plateau and is bounded on the west by the eastern Jemez Mountains and on the east by White Rock Canyon of the Rio Grande.

The geology of the Pajarito Plateau primarily reflects ancient volcanism in the Jemez Mountains and surrounding areas. The Rio Grande rift lies to the east of the plateau, forming a series of north-south– trending fault troughs from southern Colorado to southern New Mexico. Most of the fingerlike mesas in the Los Alamos area (Figure 2.1-2) are formed in Bandelier Tuff, which includes ash fall, ash-fall pumice, and rhyolite tuff. The tuff is more than 305 m (1000 ft) thick in the western part of the plateau and thins to about 79 m (260 ft) eastward above the Rio Grande. It was deposited as a result of major eruptions in the Jemez Mountains’ volcanic center about 1.2 to 1.6 million years ago. Deep canyons are incised into the Bandelier Tuff and exposed to depths of up to several hundred feet below the upper elevation of the plateau. Some of the deeper canyons expose older lava deposits and sedimentary rocks. Permeable units in the floors that outcrop below saturated alluvium create the potential for recharge to deeper groundwater zones and form a source for springs and seeps in the area. Faults, cooling joints, and fractures potentially occur throughout the Pajarito Plateau (LANL 2000, 066802, pp. 2-23–2-24).

Figure 2.1-2 Topography of the Los Alamos area

On the western part of the Pajarito Plateau, the Bandelier Tuff overlaps onto the Tschicoma Formation, which consists of older volcanic rock that comprises most of the Jemez Mountains. The conglomerate of the Puye Formation in the central plateau and near the Rio Grande underlies the tuff. Chino Mesa basalts intertwine with the conglomerate along the river. These formations overlay the sediment of the Santa Fe Group, which extend across the Rio Grande Valley and are more than 1006 m (3300 ft) thick. Most Laboratory facilities are located on tuff, covered by thin discontinuous soil on mesa tops and alluvial deposits of variable thickness on canyon floors.

Soil

Soil erodability is important to understanding the potential for contaminant transport. Characterizing soil erodability is also important for accurately completing the “contaminant transport information” in site-specific scoping evaluations (section 4.1). Soil on the Pajarito Plateau was initially mapped and described by Nyhan et al. (1978, 005702). A large variety of soil and sediment has developed on the Pajarito Plateau as the result of interactions of the underlying bedrock, slope, biota, and climate. Mesa tops may consist of soil derived from Bandelier Tuff, lavas, basalts, sedimentary rocks, and alluvium. Canyon floors generally contain poorly developed, deep, well-drained soil (Nyhan et al. 1978, 005702). General patterns of soil erosion rates are summarized by the following text from section 2.2.1.6 of the installation work plan (LANL 2000, 066802, p. 2-25):

Erosion rates vary considerably on the mesa tops; the highest rates occur in and near drainage channels and in areas of locally steeper slope gradient. The lowest rates occur on relatively gently sloping portions of the mesa tops removed from channels. Areas where runoff is concentrated by roads and other development are especially prone to accelerated erosion. The rates and processes of erosion may differ significantly between the north and south slopes of the canyons. Given current vegetation and climate, the more extensive exposure of bedrock on south-facing sides and greater soil cover on north-facing sides suggest that erosion rates of fine-grained material that can be transported by runoff are higher on the drier, less-vegetated, south-facing sides of canyons, although this material is largely retained on the north-facing slopes.

The mesa tops generally consist of finer-textured soil, and the canyon bottoms consist of relatively coarse sediment. The finer-textured soil of mesa tops is prone to overland runoff, whereas soil fines may accumulate in canyon bottoms. The latter are subject to mobilization during flood events.

2.1.4 Hydrology

Surface water on the Pajarito Plateau occurs as streams that are ephemeral (flowing in response to precipitation), intermittent (flowing in response to availability of snowmelt or groundwater discharge), perennial (flowing continuously), or interrupted (alternating perennial, ephemeral, and intermittent reaches). Some surface water arises from natural flows that originate in canyon heads in the upper Jemez Mountains north and west of the Laboratory. Other surface water originates from mesa-top storm water drainage and permitted Laboratory discharges. Perennial springs on the flanks of the Jemez Mountains supply base flow into the upper reaches of some canyons, but the volume is insufficient to maintain surface flows across the Laboratory site before they are depleted by the processes of evaporation, transpiration, and infiltration described in the “Core Document for Canyons Investigations”

(LANL 1997, 055622).

The Rio Grande is the highest-order river in north central New Mexico. Much of the surface water flow and groundwater discharge from the Pajarito Plateau canyon systems ultimately arrive at the Rio Grande through drainages that extend from the Laboratory in a southwest direction but not as continuous flow.

Only five of the canyons within Laboratory boundaries contain reaches with perennial water flow. These canyons are Los Alamos Canyon, Pajarito Canyon, Water Canyon, Ancho Canyon, and Chaquehui Canyon. In addition to these limited natural perennial reaches, several effluent-supported reaches also exist within the watersheds (LANL 2000, 066802).

Groundwater in the Los Alamos area occurs in three forms: (1) water in shallow alluvium in canyons,

(2) perched water (a body of groundwater above a less permeable layer separated from the underlying regional aquifer by an unsaturated zone), and (3) the regional aquifer of the Los Alamos area.

Groundwater hydrology for this region, including the potential for contamination, is complex.

2.1.5 Biology

The biota within the Laboratory includes approximately 500 plant species, 29 mammal species, 200 bird species, 19 reptile species, 8 amphibian species, and 1000s of insect species (LANL 2000, 066802).

The Laboratory’s Habitat Management Plan (HMP) is a document prepared to provide for the protection of federally listed threatened and endangered species and their habitats within the Laboratory boundaries. The HMP is designed to be a comprehensive landscape-scale management plan that balances the current operations and future development needs of the Laboratory with the habitat requirements of threatened and endangered species. It also facilitates DOE compliance with the Endangered Species Act (ESA) and related federal regulations (LANL 2015, 602156).

Currently, the HMP covers the following threatened and endangered species occurring or potentially occurring within the Laboratory boundaries: southwestern willow flycatcher (Empidonax trailii extimus), Jemez Mountains salamander (Plethodon neomexicanus), Mexican spotted owl (Strix occidentalis lucida), the western distinct population segment of the yellow-billed cuckoo (Coccyzus americanus), and the New Mexico meadow jumping mouse (Zapus hudsonius luteus).

Results of preliminary risk assessments for the bald eagle (Haliaeetus leucocephalus), Mexican spotted owl, and southwestern willow flycatcher are available in Gallegos et al. (1997, 057915); Gonzales et al.

(1997, 062879); Gonzales (1998, 062349); Gonzales (1998, 062350); and Gonzales et al. (2004, 085207). Information on the biology and ecology of these species relevant to risk from contaminants can also be found in these references.

There are also state-listed or other sensitive species within Laboratory boundaries that are not protected under the ESA. These species are identified by federal or state agencies or non-governmental organizations. Table 2.1-1 presents the current list of sensitive species potentially occurring within Laboratory boundaries (Hathcock et al. 2015, 602499).

Table 2.1-1

Sensitive Species Occurring or Potentially Occurring at the Laboratory

Scientific Name Common Name Protected

Statusa Potential to

Occurb

Gila pandora Rio Grande chub NMS Moderate

Falco peregrinus anatum American peregrine Falcon NMT, FSOC High

Falco peregrinus tundrius Arctic peregrine Falcon NMT, FSOC Moderate

Haliaeetus leucocephalus Bald eagle NMT, S1 High

Cynanthus latirostris magicus Broad-billed hummingbird NMT Low

Accipiter gentilis Northern goshawk NMS, FSOC High

Lanius ludovicianus Loggerhead shrike NMS High

Vireo vicinior Gray vireo NMT Moderate

Amazilia violiceps Violet-crowned hummingbird NMT Low

Myotis ciliolabrum melanorhinus Western small-footed Myotis bat NMS High

Myotis volans interior Long-legged Myotis bat NMS High

Euderma maculatum Spotted bat NMT High

Corynorhinus townsendii pallescens

Pale Townsend’s big-eared bat NMS, FSOC High

Nyctinomops macrotis Big free-tailed bat NMS High

Bassariscus astutus Ringtail NMS High

Vulpes vulpes Red fox NMS Moderate

Ochotona princeps nigrescens Goat Peak pika NMS, FSOC Low

Lilium philadelphicum var. andinum Wood lily FSOC, NME High

Cypripedium parviflorum var.

pubescens

Greater Yellow Lady’s Slipper FSOC, NME Moderate

Speyeria nokomis nitocris New Mexico silverspot butterfly FSOC Moderate

Mentzelia springeri Springer's blazing star NMSOC, FSOC, FSS

Moderate a NMS = New Mexico Sensitive Taxa (informal); S1 = Heritage New Mexico: Critically Imperiled in New Mexico; NMT = New Mexico

Threatened; NME = New Mexico Endangered; FSOC = Federal Species of Concern (no longer maintained); FSS = Forest

Service Sensitive Species; NMSOC = New Mexico Species of Concern.

b Low = No known habitat exists on Laboratory property; Moderate = Habitat exists, although the species has not been recorded recently; High = Habitat exists and the species is recorded to occur on Laboratory property.

Knowledge of the vegetative communities at the Laboratory and the animal fauna found in association with these complexes is used in the ecological risk-screening process for predicting the presence of species at the site or in the surrounding areas. For example, areas containing mature, mixed conifer stands are important to Mexican spotted owls. Knowledge and expectations from biological assessments associated with the site are then used to identify potential pathways and exposures to ecological receptors, including threatened and endangered (T&E) species.

The Laboratory has developed a vegetation land cover map (Plate 1) to support region-wide environmental studies. The land cover map identifies areas by the dominant overstory vegetation. The resulting cover types include major vegetation zones and physiognomic types important to the distribution and abundance of several T&E species (McKown et al. 2003, 087150). The individual conducting the site scoping verifies the vegetation cover type during the site visit that supports the site-specific problem scoping.

The land cover types can be subdivided to correspond with the National Vegetation Classification System (McKown et al. 2003, 087150). The elevation and climatic gradients in the region of the Laboratory most strongly influence distribution of three vegetative cover types defined by their dominant tree species and by their structural characteristics; these include piñon-juniper woodlands, ponderosa pine forests, and mixed conifer-spruce-fir forests. In contrast, aspen-riparian-wetland areas, grass species areas, shrub species areas, open water, and urban-sparse-bare rock lands are influenced less by elevation and climatic gradients. Instead, their distribution is most strongly influenced by topographic features, soil and geologic conditions, and moisture levels.

Mixed conifer-spruce-fir forests. Mixed conifer forests may be found above 2070 m (6900 ft) above sea level (asl), blended with ponderosa pine communities, but they also extend to lower elevations on north-facing slopes of canyons. These communities continue to the highest elevations of the Sierra de los Valles, 3150 m (10,500 ft). Douglas fir (Pseudotsuga menziesii) and white fir (Abies concolor) are the typical overstory dominants in mixed conifer forests. At elevations above 2700 m (9000 ft), Engelmann spruce (Picea engelmannii) becomes more important. Ponderosa pine (Pinus ponderosa) and aspen (Populus tremuloides) are also typically present. Limber pine (Pinus flexilis) can also be found in mixed conifer forests, especially on rocky ridgelines.

Aspen-riparian-wetland. Aspen (Populus tremuloides) communities are common at mid-elevations in the mountains, from approximately 2700 m to 3030 m asl (8900 ft to 9950 ft asl). Below 2820 m (9250 ft), aspen stands occupy north and northeast facing slopes, whereas above this elevation they are found mostly on southeast- to southwest-facing slopes. At higher elevations and on south-facing slopes, aspen typically exceeds 45% coverage and may be the only species present in the overstory. At lower elevations and on north-facing slopes, white fir, Engelmann spruce, and Douglas fir may collectively contribute up to 30% of the overstory coverage. Depending on the fire history of the specific stand, other tree species, such as ponderosa pine and limber pine, may be blended with aspen. Riparian areas and wetlands are also included in this vegetation land cover type.

Grass species. Grass species areas are dominated by grasses, narrow-leaf plants (e.g., yucca), and colonizing species that invade disturbed areas. Forbs and other nonshrubby species may be dominant components of these communities. Shrubs and trees are absent or rare. The grass species cover type may include areas undergoing post-fire succession, abandoned homestead areas, montane meadows, and subalpine grasslands.

Shrub species. These areas include evergreen, microphyllus shrubs, and temperate, cold-deciduous shrub species. Post-fire shrub-sized sprouts of aspen, Gambel oak (Quercus gambelii), and New Mexico locust (Robinia neomexicana) are also included in this vegetation type.

Ponderosa pine. This vegetation consists of open-canopied woodlands with needle-leaved evergreen trees, primarily ponderosa pine. An understory of Gambel oak or grasses and bare ground may occur between the trees.

Piñon-juniper. This vegetation cover also consists of open-canopied woodlands with needle-leaved evergreen trees, primarily piñon pines (Pinus edulis) and one-seed junipers (Juniperus monosperma);

bare soil may be under the trees or an understory of Basin big sage (Artemisia tridentate), and blue grama grass (Bouteloua gracilis) may grow.

Open water. This cover type includes all land that is at least periodically flooded or is open water. In the wettest of these sites, the vegetative cover is limited to plant species that require or prefer permanent or seasonally mesic conditions. The Rio Grande borders the Laboratory on its eastern boundary.

Urban-sparse-bare rock. This land type includes all undeveloped land covered by less than 7% vegetation. These land surfaces are dominated by cobbles, boulders, bedrock, or bare ground, including tuffaceous cliffs, basalt cliffs, felsenmeers, and basalt talus. Areas of sparse vegetation resulting from development, such as the Los Alamos townsite, the town of White Rock, and some TAs, are also part of the vegetation land cover class.

2.1.6 Wetlands

Wetlands are generally defined as areas of the environment containing water or moisture that support a host of aquatic plants and animals. More specifically, wetlands are defined on the basis of properties related to hydrophytes and hydrophilic plants, hydric soil, and the hydrology as described in 10 Code of Federal Regulations 1022, “Compliance with Floodplain and Wetland Environmental Review Requirements.” In and around the Laboratory, these systems occur primarily in the canyon bottoms of the Pajarito Plateau and along the banks of the Rio Grande. Wetlands may also be associated with effluent and storm water outfalls from Laboratory and county facilities. The Los Alamos Site Office, in March 2005, requested the services of and entered into contract with the U.S. Army Corps of Engineers (USACOE) Albuquerque District for the purpose of identifying and delineating wetlands at the Laboratory. Thirty wetlands occupying portions of 14 different TAs met the criteria of the 1987 USACOE Wetlands Delineation Manual, Routine Method and were identified and delineated totaling 33.955 acres (USACE 2005, 092220). The approximate locations of many of the larger wetlands are shown on Plate 1. Some of the larger wetlands on the Laboratory are located in upper Sandia Canyon, Pajarito Canyon, Mortandad Canyon, and Cañon de Valle.

The protection of wetland ecosystems at the Laboratory from the impacts of contaminants is especially important because of the diversity of associated fauna and because wetlands provide significant potential contaminant uptake pathways. These pathways include food web, direct media contact, and gamma radiation exposure pathways. Additionally, aquatic organisms occupying wetlands may experience higher exposures to contaminants because of continuous contact with water and specialized respiration mechanisms. Wetlands are of critical importance to both terrestrial and aquatic biota. Functional aspects of wetlands include food web contribution, breeding habitat, sediment retention, erosion prevention, flood and runoff storage, groundwater recharge, and nutrient retention.

2.2 Contaminant Fate and Transport

The geomorphology of the Pajarito Plateau, with its alternating mesas and canyons, determines the primary contaminant transport pathways for sources of environmental contamination. Figure 2.2-1 shows the key transport pathways:

hydrologic transport (e.g., surface water and groundwater) physical transport (e.g., mass wasting of cliffs) and atmospheric transport (e.g., dust resuspension)

These pathways are discussed briefly below. Pathways relevant to a particular site should be discussed in the applicable, site-specific reports.

S creen ing-Level E cological R isk A ssessm en t M ethods, R evision 5.1

Figure 2.2-1 Key transport pathways

2.2.1 Hydrologic Transport

2.2.1.1 Surface Water and Sediment Transport

Surface water flows provide the primary mechanism for redistributing and transporting the contaminants that remain from early Laboratory operations. The primary mechanisms affecting mobilization of contaminants within the canyons include sediment transport, contaminant dissolution and desorption, runoff, infiltration, and percolation. The water flowing across Laboratory property, especially in canyon systems, is used by wildlife, constituting a major potential contaminant exposure pathway to these receptors. Much of the surface water flow, including groundwater discharge from springs, from the Pajarito Plateau ultimately arrives at the Rio Grande.

Sediment transport by surface water may be the predominant mechanism for redistributing contaminants at the Laboratory. Carried by storm-event runoff, contamination from mesa-top release sites could enter surface-water drainages. Contaminants have also been released directly into stream channels by effluent discharges. Most environmental contaminants are adsorbed onto sediment particles, preferentially binding to particles with high surface areas and/or charged particles, such as silt and clay. The more soluble contaminants may remain in solution, which makes them available for vertical transport to perched aquifers and for later emergence in springs.

Erosion of soil and transport as sediment via surface water by runoff has significantly increased in areas of the Laboratory within or downstream of the Cerro Grande (2000) and Las Conchas (2011) burn scars.

In addition to an increase in the mass of sediment transported in the 2 to 3 yr following the fires, the concentrations of both nonradionuclides and radionuclides in sediment also increased significantly (e.g., Kraig et al. 2002, 085536; Gallaher and Koch 2004, 088747). The sediment is transported downstream and deposited at some locations where these elevated concentrations are potentially available to both terrestrial and aquatic receptors. Increased flow also leads to erosion of sediment deposits in other settings and contaminants in the mobilized sediment would mix with post-fire material and other upstream sediment sources.

2.2.1.2 Groundwater Transport

The primary mechanism for contaminant transfer between the surface and underlying groundwater is infiltration of surface water carrying colloidal and dissolved contaminants (LANL 1997, 055622). The potential for significant infiltration from mesa-top settings is typically limited by the general lack of ponded water that might create hydraulic head. In canyon settings, however, the potential for significant infiltration exists, given the presence of perennial or intermittent surface water and coarse-grained sediment in most parts of the canyon systems and the high vertical hydraulic gradients beneath canyon streams.

Saturated groundwater zones beneath the Pajarito Plateau may be recharged in part by the vertical migration of water from canyon-floor alluvium, which may be partly directed and accelerated by faults and fractures. Unsaturated zones are considered only an occasional transport pathway.

2.2.2 Mass Wasting and Mass Deposition

Physical transport of surface or subsurface materials is most dramatically possible through a mechanism termed mass wasting. Mass wasting is the process in which blocks of soil and rock break off the cliffs and are deposited violently into the canyons. Mass wasting is an episodic phenomenon and could be an important mechanism of contaminant transport for mesa-top sites located near canyon walls. Exposure to ecological receptors would result if subsurface contamination became surficial contamination through mass wasting into the canyons. The transport pathways would then be similar to media subject to surface-water transport.

2.2.3 Atmospheric Transport

Atmospheric transport may occur through transport of windblown particles or vaporization of volatile chemicals. Transport of soil or fine sediment particles by wind is a means of dispersing contaminants.

Wind resuspension and transport of surficial contaminant-laden soil or sediment is not a significant transport pathway because the volume of contaminated media mobilized by this pathway is small compared to the total amount of soil to which the receptor is exposed. Exposure of surface-dwelling animals to vapors does not represent a significant pathway because vapors disperse in the open atmosphere. Within burrows, however, vapors from subsurface contamination may accumulate and result in potentially significant exposures to animals.

2.3 Exposure Pathways

Contaminants associated with surface soil may be available to biological receptors through the following exposure pathways:

Rain splash or saltation-creep of contaminated soil onto plants

Root uptake of water-soluble contaminants

Incidental ingestion of soil

Dermal contact with soil

Inhalation of volatile chemicals by animals in burrows

Deposition of particulates on foliage

Deposition of particulates on animals, and subsequent ingestion during grooming

Food web transport (consumption of contaminated plants and animals)

Direct exposure to soil containing gamma-emitting radioactive contaminants

Contaminants associated with sediment or surface water may be taken up by biota primarily through the following exposure pathways:

Ingestion of surface water

Root uptake of surface water

Root uptake of water-soluble contaminants from sediment

Incidental ingestion of sediment

Rain splash or saltation-creep of contaminated sediment onto plants

Dermal contact with surface water or sediment

Exposure to aquatic animals through respiration

Food web transport (consumption of contaminated plants and animals)

Direct exposure to sediment containing gamma-emitting radioactive contaminants

Direct exposure to surface water containing gamma-emitting radioactive contaminants (immersion)

When groundwater becomes surface water in springs or seeps, the previous exposure pathways also apply. In addition, shallow groundwater, particularly alluvial water, may be taken up by deep-rooted plants (e.g., chamisa) and enter the food web primarily through the ingestion of contaminated plants.

Contaminants present in air as vapors are available for uptake by biota through the following exposure pathways:

Inhalation of contaminants present as vapors by animals in burrows

Uptake by plants of contaminants present as vapors

2.4 Functional Food Web

A food web diagram is important for evaluating dietary exposure pathways and for specifying ecologically relevant groups of organisms for an exposure assessment. The food web structure captures functionally relevant biotic assimilation and associated relationships and is important for selecting receptors that may be vulnerable to contaminants by virtue of dietary exposure. A food web diagram also shows pathways of food consumption in a biotic system by means of boxes and connecting arrows. Boxes in a food web diagram represent biota (e.g., functional assemblages or taxonomic groups), and arrows define the major direction of energy flow between biota (e.g., from prey to predators).

For the purposes of this ecological screening-level risk-assessment methodology, it is more useful to design a food web where biological receptors are classified into functional groups with similar feeding roles instead of a taxonomic classification. Taxonomically based food webs use phylogenetic classification to organize species into evolutionarily related natural assemblages (genera, families, orders) and are not sensitive to potentially similar feeding habits among taxa. Figures 2.4-1 and 2.4-2 represent the terrestrial and aquatic functional food webs for the Laboratory, respectively. The food webs are organized into functional guilds based on feeding (trophic) relationships. Thus, a feeding guild is a collection of species sharing common food consumption roles. For example, animals that eat seeds (granivores) are considered one feeding guild, browsers/grazers another, and top carnivores yet another. Feeding guilds may be organized in many ways, from general to specific.

A food web organized by feeding guilds forms a basis for selecting individual species from each guild that represent the guild as a whole. This approach forms the basis of receptor selection for the ecological screening assessments at the Laboratory. The food webs for the Laboratory include three fundamental trophic positions: producers (vascular and nonvascular plants); consumers (herbivores, omnivores, carnivores, and parasites); and decomposers. Within these basic trophic levels, several feeding guilds have been identified. For example, one group of consumers is herbivores, consisting of six feeding guilds:

seed eaters (granivores), fruit eaters (frugivores), foliage or leaf eaters (folivores), nectar and pollen feeders (nectarivores/pollen eaters), fungi eaters (fungivores), and browser/grazers. Since the Laboratory food web included multiple levels of organization, it was necessary to choose receptors that were broadly representative of these levels.

ing-Level E cological R isk A ssessm en t M

Figure 2.4-1 Terrestrial food web based on feeding relationships of biota on the Pajarito Plateau ing-Level E cological R isk A ssessm en t M

Figure 2.4-2 Aquatic food web based on feeding relationships of biota on the Pajarito Plateau

Aquatic environments on the Laboratory are of limited spatial extent and typically occur in canyon settings. Therefore, the primary connection between the terrestrial and aquatic food webs is not riparian species but rather aerial insectivores for which receptors are designated as part of the terrestrial food web discussed in in section 2.6.