Summitville Mine Superfund Site

INAP Meeting, October 7-8, 2009

Kevin W. Conroy, P.E.Golder Associates Inc.

Austin N. BuckinghamColorado Department of Public Health and Environment

Presentation Overview

� Site Facts, Features and History� Site Remedial Activities� Water Treatment Issues� New Treatment Facility Design

I would like to acknowledge the contributions of information andphotographs supplied by Austin Buckingham, Summitville Project Manager, CDPHE.

2

Site Facts

� Site Location� Rio Grand County, Colorado� Approximately 19 miles from South Fork, CO

� History� 1800’s through 1970’s: Historic underground mining� 1984: Galactic Resources takes over the site� 1986: Commenced open pit operations� 1992: Galactic Resources abandons the site� 1994: Added to NPL list� 1998: RI/FS begins� 2001: ROD signed

3

Site Features

� Site Features� Approximate 1,200 acre site� Average elevation ~11,500 feet amsl� Average annual snowfall of ~ 30 feet

4

SMSS During Open Pit Operations

5

SMSS During Open Pit Operations

6

Evolution of a Superfund Site

� December 1992: Galactic Resources abandons site� Poor planning� Insurmountable climactic conditions� Multiple operations violations� Cease and Desist order

� 1992-1994: Emergency response activities� Cyanide neutralization in Heap Leach Pad� Maintenance of Heap Leach Pad� Heap Leach Pad cap� Adit plugs

� May 31, 1994: Site added to NPL� 1998: RI/FS process begins� 2001: ROD signed

7

ROD Scope

� OU 0 – Interim Water Treatment� Various water treatment facilities � ~1000 gpm capacity.

� OU 1 – Heap Leach Pad detoxification and closure� Following cyanide-destruction and pad rinsing� Materials recontoured within the HLP basin� Cover-liner placed for containment and isolation

� OU 2 – Mine-waste excavation/consolidation and pit-backfilling� Cropsy waste-rock dump was backfilled into the pits� Cropsy-drainage rerouted into a new channel/pipe diversion� Both mine pits backfilled� North waste-rock dump recontoured and cap-cover fills placed

8

ROD Scope

� OU 3 – South Mountain Groundwater Assessment� Studies of the groundwater system within the remaining underground

mine workings� Complex fractured bedrock geology underlying the backfilled pits

and waste-rock areas showed mine-pool mitigation to be near-infeasible

� OU 4 – Site-wide Reclamation� Soil amendments incorporated on the cap-covers and revegetation

and erosion control commenced� Network of large rip-rapped drain-channels placed to convey runoff,

with several turn-outs installed along the perimeter toe-ditch to divert higher-flow “fresh” waters into Wightman Fork

9

ROD Scope

� OU 5 Final Remedy� On-going

� O&M of water treatment plant including management of mine pool� Continued site maintenance and monitoring� Surface water, sediment, and aquatic life monitoring in Alamosa River

and Terrace Reservoir

� Completed (balance of OU4 work)� Upgrade of select site ditches� Construction of groundwater interceptor drains� Construction of a Highwall ditch

� In Progress� Design and construction of a new water treatment plant� Upgrade of Wightman Fork Diversion� Rehabilitation of Reynolds Adit

10

Site Layout

11

OU4 Surface Water Improvements

12

Wightman Fork Diversion

13

Wightman Fork Diversion System

Penstock for micro-hydropower system

Adit Rehabilitation

14

Reynolds Adit Entrance

Reynolds Adit

Discharge Drainage

15

Stunner Area – Alum Creek

16

Aluminum Load From Summitville

17

Summitville Altered Area Aluminum Load Allocation

Legacy Mines3%

SMSS36%

Natural Conditions61%

Aluminum Load in Alamosa River

18

Load Allocation at AR41.2 (lbs/year)

Upstream Stunner6%

Stunner44%

Summitville 15%

Summiville/Legacy1%

Jasper 7%

Jasper/Legacy0%

Summitville/Natural26%

Stunner/Legacy1%

Evolution of Discharge Criteria

� ROD Remedial Action Objective� Re-establish State aquatic use classifications and attainment of

water quality numeric criteria in segment 3c� Meet all non-waived criteria at end-of-pipe� CERCLA waiver for pH, iron and aluminum in segment 3b

� Remove to extent practicable at end-of-pipe� Use segment 3b as an extended mixing zone and meet waived criteria

at top of segment 3c

� Aluminum criteria became major issue� Aluminum criteria in segment 3b originally set at 0.087 mg/L (5/1 –

9/30) and 0.75 mg/L (10/1 – 4/30)� Bench and pilot plant studies completed in 2003

� One-stage process – 5.4 mg/L� Two-stage process – 0.12 mg/L

19

Evolution of Discharge Criteria

� Two-stage process originally selected� Objections raised by EPA � Poor ambient quality in Alamosa� High cost for minimal additional aluminum removal with no surety of

improvement in Alamosa quality� CDPHE completed a Use Attainability Analysis

� Modeling performed to predict contributions to Alamosa ambient quality

� No benefit from two-stage process could be predicted� CDPHE WQCC reviewed in June 2007 and agreed� Technology-based criteria based on single-stage plant adopted

20

85th Percentile Aluminum ConcentrationsNon-Snowmelt

Site Discharge Criteria

22

Parameter Units Segment 3b Value

Comments

Aluminum mg/L 0.041, 3 (TR); 0.317, 3 (TR)

Dissolved and total recoverable chronic seasonal standard from 5/1 to 6/30; and from 7/1 to 4/30

Arsenic mg/L 0.0076 (TR) Chronic value Cadmium mg/L 0.00039 Chronic value calculated at stream

hardness Copper mg/L 0.012 Acute (3b) and chronic (3c) values

calculated at stream hardness Iron mg/L 12 (TR) Chronic value Lead mg/L 0.0022 Chronic value calculated at stream

hardness Manganese mg/L 1.58 Chronic value calculated at stream

hardness Nickel mg/L 0.047 Chronic value calculated at stream

hardness Selenium mg/L 0.0046 Chronic value Silver mg/L 0.00006 Chronic value calculated at stream

hardness for trout Zinc mg/L 0.11 Chronic value calculated at stream

hardness pH SU 6.5 – 9 -

Site Water Quality

23

Parameter Units Average Maximum Projected Discharge

Goal Segment 3b

Parameters with discharge goals Aluminum mg/liter 136 245 5.4 0.041

Arsenic mg/liter TR 0.1 1.04 <0.1 0.0076 Cadmium mg/liter 0.13 0.32 <0.002 0.00039 Copper mg/liter 44 120 0.007 0.012 Iron mg/liter TR 156 644 0.12 12 Lead mg/liter 0.05 0.27 <0.001 0.0022 Manganese mg/liter 30 31 1.0 1.58 Nickel mg/liter 0.57 0.94 <0.04 0.047 Selenium mg/liter <0.02 -- <0.0046 0.0046 Zinc mg/liter 15.6 32 0.008 0.11 Parameters important in treatment plant design Calcium mg/liter 98 171 642 -- Chloride mg/liter 8 -- -- -- Magnesium mg/liter 39 63 22 -- Potassium mg/liter 4 -- -- -- TDS mg/liter 3,419 5,657 3,047 -- Sodium mg/liter 20 -- -- -- Sulfate mg/liter 2,165 3,786 1,990 --

Final Process Flowsheet

24

Final Process Flowsheet

25

Process Design

� Flow – 1,600 gpm� Based on hydrologic modeling� Balanced with SDI capacity

� Reaction System� pH 9.5 maximum� 45 minute retention time in Reaction Tank� Sludge recycle and lime fed to Mix Tank� Floc Tank prior to Clarifier

� Clarifier diameter � Diameter – 70 feet� 15 solids recycles� 12.5 ft2/STPD � 10% solids underflow

26

Process Design

� Lime usage� Slaker system to be used� 1,200 pounds per hour� 4,000 ft3 storage capacity

� Solids management� Production – 1.85 gr/L� 36 hours storage capacity� Filter press capacity – 225 ft3

� Polymer system� Dry polymer system

� Utilities� Redundant air compressors� Small membrane system for makeup water

27

Process Design

� Systems allowed for but not installed� Iron addition� Anti-scalent� Neutralization

� Material of construction� Epoxy coated steel – main tanks� Glass lined – clarifier tank� Polypropylene lined steel – low pH piping� HDPE – underground piping

28

Equipment Layout

29

Architectural Design

� Long design life (50 years)� Need to be self-sufficient

� Lab� Vehicle maintenance� Parts storage� Locker rooms

� Weather conditions� Snow drifting/loading and associated damage

� Architectural features� Precast concrete panels for lower 16 feet� Metal panels above� Sandwiched insulation� Flat roof structure

30

Architectural Design

31

Architectural Design

32

Civil/Structural Design

� Civil� Constrained site

� Topography not good� Relationship to SDI and existing utilities important

� Site drainage important� High groundwater levels� Seeps

� Geotechnical investigations� Soil borings� Lab testing� Geophysical investigation

� Foundation System� Drilled pier foundation system� Grade beams and structural slab

33

Civil/Structural Design

34

Miscellaneous Design Elements

� Fuel farm� New SDI pump system� Backup generator

� Life safety systems� Raise clarifier rake

� Extensive lightning protection system� Fire detection system� Communications

� Radio-based phones� Satellite-based Internet

35

What made the project a reality?

� Economic Stimulus money

� Willingness of regulatory community to understand the nature of ambient water quality in the Alamosa River

� Continued stakeholder involvement

� Excellent relationship between CDPHE and EPA Region 8

36

Questions?

37