UNITE D

STATE S ENVIRONMENTA L

PROTECTIO N AGENC Y REGIO N VIII 9 9 9 18t h STREE T
- SUIT E 60 0 DENVER

, COLORAD O 80202-246 6

INITIA L POLLUTIO N REPOR T Midval e Sla g OU 2 Abandone d Well s 

### 2702 0 

# S F FIL E NUMBE R

I

. HEADIN G Date : Sub j ect: From : T o : POLRE P No

. 10/10/9 6 Midval e Sla g NP L Site (OU2 ) Abandone d Well s Mik e Zimmerman
, OS C /Yy\oL 4 Ann e Spencer

, EP A Headquarter s Emergenc y Respons e INITIA L POLRE P # 1

7 1 UTD08183427 7 CERCL A UDE Q Notifie d 07/26/9 6 10/3/9 6 N / A I I

. BACKGROUN

D Site No. : . CERCLI S No : Respons e Authority : State Notification : Actio n Memorandum : Star t Date : Completio n Date : III

. SIT E INFORMATIO N A

. Inciden t Categor y Time-Critical

, NP L B

. Site Descriptio n 1

. Site Descriptio n'' j T h e entir e Midval e Sla g sit e consist s o f abou t 53 0 acres ; OU 2 cover s abou t 20 0 acre s o f the Site

. A smelte r operate d on OU 2 fro m 189 7 unti l 1958

. lOver the years , i t change d fro m a coppe r t o a lea d smeltin g facility
, producin g gold/lead/silve r

bullio n fro m sulfid e ores
. Fiv e well s wer e installe d o n OU 2 i n 193 6 i n th e Dee p Principa l Aquife r fo r th e purpos e o f supplyin g wate r t o th e smelter

. Durin g th e demolitio n o f th e smelte r i n 1960 , th e surfac e casings o f the well s wer e damage d and severa l o f the wel l head s wer e covere d wit h demolitio n materials

. I t appear s tha t th e well s remaine d i n a n unprotecte d conditio n fo r man y years ,
Printed on Recycled Paper

### makin

g i t likel y tha t surfac e wate r an d windblow n smelte r • I ; ; wast e material s entere d th e casings

. 2

. Descriptio n

o f Threa t 

### A s a resul t o f damaged/deteriorate d

surfac e casin g o f 5 well s o n th e OU 2 site , surfac e wate r an d windblow n smelte r wast e material s hav e entere d the wells
, and the y no w sho w elevate d concentration s

o f severa l metals
, especiall y barium and cadmium

. Sinc e ther e ar e abundan t concentration s

o f 

### lead
, arsenic , copper , silver
, chromium
, an d zinc i n th e slag
, dross
, an d baghous e dus t foun d o n th e Site fro m previous smelte r operations , i t i s possibl e tha t additio n 

### metal s coul d migrat e int o th e well s i n th e future

. Because 

### thes e well s ma y b e actin g a s conduit s fo r contaminatio n

t o th e underlyin g aquifer
, the y wil l b e abandone d an d plugged

. C

. Sit e Evaluatio n Result s 

### Durin g th e EE/C A field investigatio n

i n 1993 , th e surfac e casings fo r thes e 5 forme r water-suppl y well s wer e located

. Tw o o f th e well s wer e sample d an d showe d elevate d concentrations greate r tha n th e Maximu m Contaminan t Leve l (MCL ) fo r tota l an d dissolve d bariu m an d cadmium

. Thes e elevate d concentration

s 

### migh t b e accounte d fo r b y surfac e wate r infiltratio n du e t o severel y deteriorate d wel l casing s a t th e surface

. I V

. RESPONS E INFORMATIO N A

. Situatio n 1

. Curren t Situatio n O n Octobe r 3 , 1996 , the EP A ERG S Contracto r mobilize d 

### t o th e Sit e t o begi n th e pluggin g an d abandonmen t o f th e fiv e (5 ) wells

. Th e wel l stem s o n th e nin e (9 ) monitorin g well s wil l b e remove d and the well s wil l b e plugge d and abandoned

. Whe n thi s i s complete d i t wil l remov e a condui t fo r contaminatio n

an d a n obstacl e t o futur e remediation

. 2

. Nex t Step s 

### T h e Contracto r plan s t o complet e th e pluggin g an d abandonment o f th e well s withi n 3 weeks

. V

. COS T INFORMATIO N Sinc e thi s i s th e initia l POLREP

, cost s ar e stil l minimal

.POLREPFILE GENERATION (to be submitted

by OSC with initial

Polrep) Sit e Name : N l t

O O & U S "SiUVC g - A ^ ft- H O o 64€ O ^ ^ <JLS > City/County/State : M SSZD #0. I/

CASENO.

Polreps Dist. List 1. Program Dir., Doug Side, T. Leaders: Jim Knoy, Steve Hawthorn, Luke Chavez (rotating) 2. RA, DRA, ARAships 3. ERD - Headquarters ATTN: Director (5202G) 4. Region Response Team Members (via fax - 19 members) 5. 8OC

ATTN: Rich Lathrop 6

. Lega

l Depar t (ENF) ATTN : Oots-vM ^ A\^5HJ>Q

. , ttS-\ c - 7

. osc : M,u< e 8. EPS 9. Adm. Records Coordinator 10. State Program Director/Manage

r \4 g ^ T G 0.^

^ ^ O Addres s "3

. U 11. National

Pollution Fund

Center: Y

01 12. Ann Spencer

HQ/EPA 703/603-9116