APPENDIX = C

RESPONSIVENESS SUMMARY

1.1 = Stakeholder Issues and EPA=20 Responses

During the=20 Public Comment Period for the Proposed Plan, comments were received from = UPCM,=20 the Marsac Corridor Association and Utah Department of Fish and = Wildlife. Their comments and EPA=92s = response to=20 these comments are in the following sections.

1.1.2 Comments Received From = United=20 Park=20 City=20 Mines

Remedy = Selection. =20 United Park supports the remedy selected in the Proposed = Plan. Like EPA, United = Park believes that Alternative 3 = provides=20 more than adequate protection of human health and the environment, will = prove to=20 be effective (both in the long and short terms), will be cost-effective, = and=20 will otherwise address the remaining environmental conditions necessary = to=20 achieve final closure of the Site. =20

Possible Wetlands Operable=20 Unit. The Proposed Plan states that = the timing=20 of remediation as to the small wetland area between the impoundment and = Silver=20 Creek will be delayed until upstream remediation and reclamation efforts = are=20 complete. United Park=92s = understanding is that the wetland area will be remediated following = remediation=20 of several upstream areas, some of which are located on United = Park property. In any event, because the = timing for the=20 remediation of the wetland area will not be linked to the remediation = process=20 for the remainder of the Site, United Park suggests that EPA consider=20 designating the wetland area as a separate operable unit. EPA has the discretion to = designate=20 multiple operable units with respect to the Site. Doing so here makes sense in = part because=20 it will facilitate negotiation of the anticipated Consent Decree, = enabling EPA=20 and United=20 Park to define = construction=20 completion as to each operable unit.

EPA Response: = While EPA understands this is = an option=20 that would allow the Site to be archived by OU more quickly, EPA feels = strongly=20 that the timing of cleanup throughout the Watershed will work to = everyone=92s=20 advantage. By cleaning up = the=20 upstream sites along Silver Creek in a time efficient manner, the Site = wetlands=20 can then be excavated according to the plan set forth in this ROD. It is critical to EPA that the = entire=20 Silver Creek Watershed be addressed and by further dividing sites by OU = or=20 through some other approach, EPA believes this will slow the process = down rather=20 that expedite it.

Site Impacts on Silver=20 Creek. There are a number of = statements in the=20 Proposed Plan suggesting that the Site is presently having a significant = impact=20 on water quality in Silver Creek. =20 See page A-2 (first = paragraph)=20 (linking Site to other sites that are all impacting Silver Creek); page = A-3 and=20 A-4 (remediation of Site will play direct role in watershed = remediation). United Park finds these = statements=20 confusing. The Remedial=20 Investigation (=93RI=94) for the Site determined that surface waters = leaving the=20 Site present no significant impact on water quality in Silver = Creek. While it is true that surface = waters in=20 areas upstream of the south diversion ditch exhibit elevated metal=20 concentrations, the water in the south diversion ditch outfall has = consistently=20 met surface water quality standards. =20 The remedial action proposed for the Site is more appropriately = described=20 at addressing potential = future=20 impacts the Site may have on Silver Creek. =20 While United = Park recognizes that many of the issues = addressing=20 Silver Creek arose generally from historic mining operations, United = Park believes it is = inappropriate to group=20 the Site with other areas in the Silver Creek Watershed that may have = actual=20 present impacts on water quality in Silver Creek.

EPA Response: =20 EPA recognizes that the data from the Remedial Investigation = relating to=20 the Site=92s impact on Silver Creek support this statement. It was written in the Proposed = Plan that=20 historic mining activities throughout the Upper Silver Creek Watershed = have=20 adversely affected Silver Creek. = In=20 Section 12, The Selected Remedy, and in Section 5, Summary of Site=20 Characteristics, it is made clear that water from the Site that enters = Silver=20 Creek is of better quality than Silver Creek itself. It is accurate to state = that the=20 selected remedy will be protective of human health and the environment = in that=20 it will minimize any future exposures or impacts contamination at the = Site may=20 present.

Human and Ecological=20 Risks. United Park believes that the = Proposed=20 Plan mischaracterizes the results and findings of the human health and=20 ecological risk assessments relating to the Site. More specifically, the = discussion in the=20 Proposed Plan under Human Health Risks (page A-4) states that "if the = necessary=20 cleanup action is not taken . . . there is a risk to future recreational = users=20 at the Site because of lead and arsenic present in the tailings." In fact, the Baseline Human = Health Risk=20 Assessment ("BHHRA") conducted by EPA concluded no significant risk to=20 recreational users of the Site from the existing soils and mine tailings = unless=20 the soil cover is somehow disturbed. =20 With respect to the ecological risk assessment discussion, the = Proposed=20 Plan states that the Ecological Risk Assessment ("ERA") determined that=20 ecological receptors are potentially exposed to metals in several ways, = as=20 summarized in the chart on page A-4 of the Proposed Plan. It would be more accurate to = state that=20 the ERA concluded contaminated sediment in the wetland area is the = primary=20 ecological risk driver, although surface water in a portion of the south = diversion ditch may also present some risk, to a lesser degree. This conclusion is supported = by Table=20 7-8 in the ERA.

EPA Response: =20 Again, it is EPA=92s intent to make it clear that if the = necessary remedial=20 actions are not taken at the Site, which include both enhancing the soil = cover=20 and ensuring that it will remain intact in the future, potential risks = to human=20 health and the environment exist. =20 EPA agrees with the comment addressing sediments as the primary = risk=20 driver at the Site.

Future Consolidation of=20 Material. United Park understands the = practical=20 benefits that could arise from the future use of the Site as a = consolidation=20 area for mining materials and impacted soils. However, United = Park notes the potential = complications=20 related to defining completion of construction for purposes of the = remedial=20 action described in the Proposed Plan. =20 United Park suggests that one way to address this concern would = be for=20 EPA to provide in the ROD that: = (i)=20 any materials so consolidated at the Site during implementation of the = remedial=20 action will simply be incorporated into the remedial action and covered = with the=20 required amount of clean = cover=20 material and revegetated; and (ii) any material to be consolidated after = completion of construction will be subject to institutional controls = requiring=20 that mine wastes or impacted soils consolidated at the Site after the = remedial=20 action is completed would be covered with the required amount of clean material and = revegetated. This will allow United = Park to achieve a state of = completion with=20 the remediation while providing maximum flexibility for the future = consolidation=20 of material from the Watershed and any potential reuse of the=20 property.

EPA = Response: =20 EPA agrees with this comment; evidence of incoorporation of this = comment=20 into the ROD can be found in the Remedy Selection=20 section.

1.1.3 Comments=20 Received from the Marsac Corridor Association

One = component of=20 the remedy allows for waste to be transported from Empire = Canyon and deposited at = Richardson=20 Flat. The Marsac Corridor = Association (MCA) is a group of homeowners that live in the neighborhood = through=20 which trucks carrying the waste would drive. The members of the MCA had two = specific=20 comments: 1) The waste in Empire=20 Canyon should be left in = place, and 2)=20 If the waste must be moved, it should be transported up the Mine = Road and down=20 Royal=20 Street, rather than using only the = Mine = Road and=20 Lower Marsac.

EPA Response: EPA understands MCA=92s concerns = and has=20 considered its comments. = It is our=20 perspective that the waste may be left in place or moved to Richardson = Flat. Factors such as space to = contain the=20 waste, the cost of transportation, and potential migration of waste left = in=20 place will be considered by the parties involved in order to make a = decision=20 about the fate of the waste in Empire Canyon. EPA understands that = this is a=20 local issue and one that will be resolved through discussion and = consideration=20 amongst the stakeholders. = These=20 stakeholders include Park City, UPCM, MCA and other = concerned=20 public. A public hearing = will be=20 held by Park=20 City in the = upcoming future=20 to resolve this issue. =

1.1.4 Comments=20 Received from United=20 States Fish and Wildlife Service (the = Service)=20 Utah Field Office

The = Service=20 submitted comments concerning the remedy=92s protectiveness in relation = to=20 ecological receptors at the Site. =20 The Service=92s primary concern is that the sediments found in = the South=20 Diversion Ditch, the pond at its terminus and in the wetland at the base = of the=20 embankment are not being addressed in a manner efficient enough to = substantially=20 minimize risk to ecological receptors at the site. The Service proposes = excavation of the=20 sediments in all three areas.

EPA=20 Response: The sediments within the = wetland area=20 will be excavated and placed within the impoundment through the selected = remedy. EPA understands = that the=20 wetland is a naturally occuring ecological phenomenon that existed = before the=20 impoundment was created. = Therefore,=20 the remedy should allow for the restoration of the wetland as a habitat = for=20 ecological receptors at the Site. =20 However, the diversion ditch and small pond are engineered = features at=20 the site that were constructed to help contain the tailings in the = impoundment=20 and minimize groundwater infiltration from Area B into the main=20 impoundment. Therefore, = these areas=20 will be sufficiently remediated through the described mechanisms = (placement of=20 18 inches of gravel over contaminated sediments). While this action does not = create=20 habitat or restore habitat, it will minimize risk to ecological = receptors at the=20 Site. The requirements = set forth in=20 the NCP are met. Lastly, = this does=20 not preclude continued negotiation concerning the restoration of these = features=20 between UPCM and EPA surrounding Natural Resource Damages. These damages are currently = being=20 addressed, and they are a complicated issue. It is possible these damages = could be=20 mitigated through the restoration of other areas within the = Watershed. So, until a settlement = concerning these=20 damages has been reached the exposure pathways will be interrupted with = gravel=20 and risk to ecological receptors will be minimized in the diversion = ditch and=20 the pond at its terminus as it is described in the selected=20 remedy.

APPENDIX=20 A

FIGURES FOR = THE RECORD=20 OF DECISION

APPENDIX=20 B

TABLES FOR THE = RECORD OF=20 DECISION

Table 7-1

Summary of Chemicals of = Concern and=20

Medium-Specific Exposure = Point=20 Concentrations

Scenario=20 Timeframe: =20 Current

Medium: &nbs= p; = ;=20 &n= bsp; =20 Sediment

Exposure=20 Medium: =20 Sediment

Exposure=20 Point

Chemical = of Concern

Concentration=20 Detected

Units

Frequency = of=20 Detection

Exposure = Point=20 Concentration

Exposure = Point=20 Concentration Units

Statistical = Measure

Min

Max

Sediment:=20 Ingestion

Arsenic

101

310

mg/kg

12/12

200

mg/kg

95% = UCL

Lead

1,880

6,520

mg/kg

12/12

3,500

mg/kg

Key: =20

mg/kg: = milligrams per=20 kilogram

95% UCL: = 95% Upper=20 Confidence Limit of Arithmetic Mean

MAX: = Maximum=20 Concentration

AM:=20 Arithmetic Mean

Table=20 7-2

Summary of Chemicals of = Concern and=20

Medium-Specific Exposure = Point=20 Concentrations

Scenario = Time=20 frame:=20 Current

Medium: &nbs= p; =20 Surface Water

Exposure=20 Medium: Surface=20 Water

Exposure=20 Point

Chemical = of Concern

Concentration=20 Detected

Units

Frequency = of=20 Detection

Exposure = Point=20 Concentration

Exposure = Point=20 Concentration Units

Statistical = Measure

Min

Max

Surface = Water -=20 Ingestion/ dermal exposure

Arsenic

0.025

0.75

mg/L

99/291

0.012

mg/L

95% = UCL

Lead

260

0.0015

mg/L

211/425

0.13

mg/L

Key =20

mg/L: = milligrams per=20 liter

95% UCL: = 95% Upper=20 Confidence Limit

MAX: = Maximum=20 Concentration

&nbs= p; = ; = &= nbsp; &n= bsp; &nb= sp; &nbs= p; = ; = &= nbsp; &n= bsp; =20

&nbs= p; =20

Table=20 7-3

Summary of Chemicals of = Concern and=20

Medium-Specific Exposure = Point=20 Concentrations

Scenario = Time=20 frame:=20 Current

Medium: &nbs= p; =20 Soil & Tailings

Exposure=20 Medium: Soil & = Tailings

Exposure=20 Point

Chemical = of Concern

Concentration=20 Detected

Units

Frequency = of=20 Detection

Exposure = Point=20 Concentration

Exposure = Point=20 Concentration Units

Statistical = Measure

Min

Max

Soil&=20 Tailings:

Ingestion

Arsenic

2.5

2400

mg/kg

59/64

mg/kg

95% = UCL

Lead

5900

mg/kg

62/62

660

mg/kg

Key =20

mg/kg: = milligrams per=20 kilogram

95% UCL: = 95% Upper=20 Confidence Limit

AM: = Arithmetic=20 Mean

Table 7-4

Cancer Toxicity Data Summary

Pathway:=20 Ingestion

Chemical = of Concern

Oral Cancer = Slope=20 Factor

Slope = Factor Units=20

Weight of=20 Evidence/Cancer Guideline Description

Source

Date

Arsenic

1.5

(mg/kg)/day

Region 3 = RBC=20 Table

8/28/2001

Lead

KEY

EPA=20 Group:

A- Human=20 carcinogen

B1 = -Probable human=20 carcinogen - Indicates that limited human data are=20 available

B2 = -Probable human=20 carcinogen - Indicates sufficient evidence in animals and = inadequate or no=20 evidence in humans

C -Possible = human=20 carcinogen

D -Not = classifiable=20 as a human carcinogen

E -Evidence = of=20 noncarcinogenicity

RBC- Risk = Based=20 Concentration

NA: Not=20 Applicable

Table 7-5

Non-Cancer = Toxicity Data=20 Summary

Pathway:=20 Ingestion

Chemical=20 of = Concern

Chronic/

Subchronic

Oral=20 RfD Value

Oral=20 RfD Units

Dermal = RfD

Primary=20 Target Organ

Combined Uncertainty/

Modifying=20 Factors

Sources=20 of RfD:

Target=20 Organ

Dates=20 of RfD:

Target=20 Organ

Arsenic

Chronic

3.0E-04

mg/kg-day

=97

skin

=97

Region=20 3 RBC Table

8/28/01

Lead^a

=97

Key

(1)=20 The dermal RfD was assumed to equal the oral RfD. No adjustment factor was = applied

(2)=20 Toxicity values were pulled from the EPA Region 3 RBC=20 Table

a=20 There are no established criteria for lead; evaluation is made = using blood=20 lead levels

Table=20 7-6

Risk Characterization Summary = =96=20 Carcinogens

Scenario=20 Timeframe: = =20 Future

Receptor=20 Population: = =20 Low Intensity Recreational User

Receptor = Age: = &n= bsp; Child-Adult

Medium

Exposure=20 Medium

Exposure=20 Point

Chemical of = Concern

Carcinogenic=20 Risk

Ingestion

Inhalation

Dermal

Exposure = Routes=20 Total

Soil/Tailings

Ingestion

Arsenic

2E-05

---

2E-05

Dust

Inhalation

Arsenic

---

3.5E-10

Soil risk total=3D

2E-05

Sediment

Ingestion

Arsenic

3E-06

---

3E-06

Sediment Risk = Total=3D

3E-06

Surface=20 Water

Ingestion

Arsenic

1.8E-07

---

2.0E-07

Surface = Water Direct=20 Contact

Arsenic

---

3E-08

3.0E-08

Surface = Water Risk=20 Total

4E-07

Total Risk =3D

2E-05

Key

NA: Route of exposure is not = applicable to this medium.

NE: Not evaluated=20

=20