AK STEEL LETTER RE: ADDENDUM TO REVISION 2 OF THE 3013 ...

Al" Steel Corpo,·ation Environmental Affairs 9227 Centre Pointe Drive West Chester, Ohio 45069

December 17, 2012

Ms. Christine McConaghy Project Manager U.S. EPA, Region 5 77 West Jackson Boulevard, LU-9J Chicago, IL 60604-3590

RE: Addendum to Revision 2 of the 3013 Order Final Report, AK Steel CorporationZanesville Works U.S. EPA ID No. OHD004281598

Dear Ms. McConaghy:

AK Steel Corporation (AK Steel) acknowledges your approval with modifications of the Final Report for the RCRA 3013 Order Investigation (Revision 2)1 as provided in your November 6,

I# 2012 approval letter. Per your request, AK Steel is submitting this addendum in response to the ~,four comments provided in your approval letter. To assist your review, EPA's comments are

shown below in italics followed by AK Steel's responses. Also, to assist the review of our responses, we have compiled figures showing soil and groundwater sampling locations related to the investigation of hexavalent chromium at the site (Figures 1 and 2, respectively) and a summary of these investigative activities (Table 1 ). Previously, this information was provided in multiple figures and tables.

Comment 1. Provide a summary of all reviews of maintenance records that AK Steel has undertaken with respect to the source of chromium in groundwater. Include the scope of the review (e.g. types and dates of records reviewed). Also include copies of any correspondence related to records reviews.

AK Steel Response

During your site visit conducted at the time of the off-site groundwater investigation in May 2010, we discussed the review of maintenance records regarding potential sources for the hexavalent chromium detected in MW-27A in 2004/2005. As I explained at the time, there were not any maintenance records I felt would be relevant or helpful to review given my familiarity · with the plant operations since 2001, my regular and routine reviews of potentially relevant work such as tank and containment inspections, and perhaps most importantly, interviews I had previously conducted with several experienced engineers and maintenance managers at the facility. Tanks and secondary containment structures are routinely inspected as part of normal operations and any issues or abnormal conditions are communicated to management. As an example, in October 2010 an inspection of the secondary containment structure for the Koliquid tank associated with the No. 1 AP Line showed that there was some minor deterioration of the

1 Final Report/or the RCRA 3013 Order Investigation-Revision 2, AK Steel Co,poration-Zanesville Works, Zanesville, Ohio, Cox-Colvin & Associates, Inc., April I, 2010

962094

Ms. Christine McConaghy December 17, 2012

Page2 concrete surface. As a proactive measure, AK Steel repaired the concrete surface and applied a coating to the interior of the secondary containment structure in an effort to ensure its integrity.

AK Steel takes material releases very seriously and has strict policies in place that require the reporting of spills of even minor volumes of liquids. There is no specific knowledge of a release or other type of maintenance event that would be related to the hexavalent chromium.

Comment 2. Provide an update to the source discussion for chromium in groundwater. Summarize any trends in chromium levels in groundwater from April ], 2010 to present. On page 69 of the Report, you discuss some anticipated future work to "continue to develop a hypotheses concerning hexavalent chromium dynamics. "Provide a summary of the data needed to continue developing the hypotheses.

AK Steel Response

Table 2 provides a summary of hexavalent chromium concentrations detected at monitor well MW-27A between April 2010 and September 2012 (total of 10 sample analyses). Hexavalent chromium was detected above the method detection limit (MDL) in seven samples. Of these seven detections, only one concentration was above U.S. EPA's regional screening level (RSL, 0.11 mg/L). The data were evaluated statistically using Sen's Slope Indicator test and no upward trend in the data was evident. The Sen's Slope Indicator test, conducted using the commercially available ChemStat™ software, is a non-parametric method of estimating the true slope ( change in concentration over time) of the data. Because this method is non-parametric, it is suitable for a high percentage of non-detects and is not significantly affected by outliers. The ChemStat™ output for this evaluation is provided in Attachment I.

The future work discussed on page 69 of the April 20 IO Final Report was realized with the implementation of a regional aquifer investigation2 conducted in May 20 IO in the area north (hydraulically downgradient) of the Zanesville Works property. As reported in the July 2010 regional aquifer investigation report3, hexavalent chromium was detected at estimated concentrations below the RSL in six disassociated geoprobe sampling locations ( one in the shallow, two in the intermediate, and three in the deep pmiions of the aquifer). Therefore, a discernible plume of hexavalent chromium was not evident in groundwater downgradient of the Zanesville Works in either the shallow, inte1mediate, or deep portions of the regional aquifer. As reported in the Final 3013 Order Report, the source for hexavalent chromium is likely within

2 Streamlined Scope of Work.for Additional Off-Site Groundwater Investigation-Revision I, AK Steel Corporation-Zanesville Works, Zanesville, Ohio. Cox-Colvin & Associates, Inc., March 22, 2010. 3 2010 Regional Aquifer InvesNgation Results, AK Steel Corporation-Zanesville Works, Zanesville, Ohio, CoxColvin & Associates, Inc., July 21, 2010.


a relatively small area that is somewhere in the vicinity of the central portion of the No. I AP Line, the SWMU 7/9 secondary containment area, and the adjacent truck loading/unloading area. As su111111arized herein in Figure I and Table I, drilling and soil sampling has been conducted in in a significant number of accessible locations within this area in an effort to determine the source. The results from this investigation indicated the presence of hexavalent chromium in soil; however, the results were inconclusive with regard to a source for the hexavalent chromium detected in MW-27A in 2004/2005. As shown on Figure 2 and Table I, extensive on-site and off-site groundwater investigations have also been conducted to identify the source and delineate the extent of hexavalent chromium in groundwater. Groundwater sampling efforts have been inconclusive with regard to identifying the source for the hexavalent chromium detected in MW-27 A. Furthermore, the results of the 20 IO off-site groundwater investigation did not indicate the presence of a discernible plume of hexavalent chromium downgradient of the Zanesville Works. Based on the results of the soil and groundwater sampling efforts, we do not believe that additional investigative activities will further assist identification of the source of the hexavalent chromium.

Comment 3. Elaborate on your discussion {page 63) of the potential that hexavalent chromium detected in groundwater has its source in the vadose zone soils that were impacted by the release of spent pickle liquor (K062). Provide additional background for the statement that: "Although other metals are present, including total chromium, the fluoride plume generally does not contain hexavalent chromium. As such, it is clear that the hexavalent chromium in groundwater discussed below in Section 5.20.3 does not originate from the same source as the fluoride." Chromium is a constituent in spent pickle liquor according to the K062 Listing Background Document: Resource Conservation and Recovery Act (RCRA), Subtitle C.

Section 261.31 and 261.32 - Identification and Listing of Hazardous Wastes - Steel Finishing, EPA-HQ-RCRA-2004-0017-0030, accessible at http://www.regulations.gov/#! documentDetail;D~ EP A-HQ~RCRA-2004-0017-003 0.

AK Steel Response

The statement that "the fluoride plume generally does not contain hexavalent chromium" is based on evaluation of historical hexavalent chromium analyses from recovery/monitor wells that are known to have been affected by the 1994 release based on the presence of flnoride above background (i.e., CP-01, MW-09, MW-09D, MW-09DD, MW-10, MW-11, MW-25, and MW-28A). From 2002 to 2012 there were 310 hexavalent chromium analyses conducted on groundwater samples collected from these wells. Hexavalent chromium was detected in only 11 samples (approximately 3% of the 310 samples), typically at low estimated concentrations between the PQL and MDL. If the 1994 release was the source for the elevated levels of hexavalent chromium detected in MW-27A, we would expect to see these elevated levels

consistently in wells near the release (particularly CP-01).


Page4

Further evidence is based on groundwater flow conditions. Review of 10 years of groundwater flow data shows that the direction of groundwater flow in the vicinity of the 1994 release is generally northward, and not westward toward MW-27A. Although the direction of groundwater flow can shift westward periodically due to the interaction of groundwater and the Muskingum River, any westward flow in this po1iion of the prope1iy is likely short lived and may not be sufficient to cause constituents released in 1994 to migrate to MW-27 A.

Based on these lines of evidence, we believe that it is unlikely that the 1994 pickle liquor release and the hexavalent clu·omium detected in MW-27A in 2004/2005 are related. However, given the amount of time that has elapsed since the release, and the uncertainties of contaminant migration and geochemistry in such a dynamic groundwater enviromnent, we cannot definitively conclude that these events are unrelated.

Comment 4. Discuss the potential that for certain limited periods of time, such as during extreme dry weather, the Muskingum River is a gaining stream.

AK Steel Response

Whenever surface water levels in the Muskingum River are lower than groundwater levels in the aquifer, the river would indeed technically be gaining water from the aquifer. However, direct measurements of surface water and groundwater levels collected during the 3013 Order investigation suggest that this is a rare occurrence. To illustrate the interaction between the river and groundwater, a hydrograph (Figure 3) was prepared using 10 years of measurements collected from the river (AK Steel pump house) and four monitor wells located near the river (MW-01, MW-02, MW-04, and MW-06). As the hydrograph shows, surface water levels from the river have only occasionally been observed to be lower than groundwater levels. Furthermore, because these conditions (gaining stream conditions) appear to be short lived, it would not be likely that they would have a significant impact on overall groundwater flow and constituent migration throughout the Zanesville Work property.

We appreciate your input and continued support in helping to bring this project to a successful conclusion. If you have any questions, or require additional information, please do not hesitate to contact me at (513) 425-2711.


Page5 I ce1tify after my diligent review and to the best of my knowledge, information, and belief, that the information contained in or accompanying this submission is trne, accurate, and complete.

Respectfully Submitted, AK Steel Corporatio

Leveng od Corporate Manager of Environmental Affairs AK Steel Corporation-Zanesville Works

cc: Laura Hughes, Ohio EPA-DERR SEDO Gregory. S. Kinsall, Cox-Colvin & Associates, Inc.

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Table 1. Summary ofHexavalent Chromium Investigative Activities at the Zanesville Works, AK Steel Corporation-Zanesville Works, Zanesville, Ohio.

une LUU3

August 6 through 14, 2003

August, September, December 2003

March 24, 2004

April 7, 2004

June and September 2004

December 15, 2004

January 12, 2005

March 10, 2005

hme 15, 2005

August 4, 2005

August 18, 2005

September 23, 2005

October 2005

December 8, 2005

March 2, 2006

April 2006

September and October 2006

March 1, 2007

March 29, 2007

August 2007

June 2006 through March 2009

June 25, 2009

September 24, 2009

December 16. 2009

March 17, 2010

May 5, 2010

April 26 through May 6, 2010

Event

Monitor well MW-27A installed as part of the Phase I 3013 Order-related investigation.

Soil sampling at SWMUs 4, 6, 9, and JO as part of the Phase I 3013 Order-related investigation Total of37 samples collected from 11 locations at depths ranging from 2 ft to 27 ft bgs.

Two rounds of sampling for the Phase I 3013 Order-related investigation and one routine quarterly sampling ofMW-27A

Routine quarterly sampling ofMW-27A

MW-27Aresampled.

Routine quarterly sampling of MW-27 A

Routine quarterly sampling ofMW-27A.

MW-27A resampled

Routine quarterly sampling ofMW-27A

MW-27 A resampled.

MW-27A resampled.

MW-27 A resampled.

MW-27A resampled.

Geoprobe groundwater samples collected at 20 locations from a grid pattern on Lear property.



Geoprobe groundwater samples collected at 6 additional locations from a grid pattern on Lear property and from five locations along the northern portion on AK Steel property (samples collected at 30 ft, 50 ft, or 70 ft bgs).

Geoprobe soil sampling at SWMU 9 (11 samples from four locations) and geoprobe soil (52 samples from si.x locations) and groundwater sampling (nine samples from nine locations) north of the AK Steel No. 1 AP Line building (chromium source area investigation) as part of the Phase 113013 Order-related investigation.

Geoprobe groundwater sample collected at one located at SWMU 9 at a depth of33 ft bgs.

Geoprobe groundwater samples collected at SWMU 9 at three locations surrounding March 1, 2007 sampling location at depths of30 ft bgs

32 geoprobe groundwater samples collected at 30 ft and 70 ft bgs at 16 locations (one inside AK Steel building upgadient of the No. l AP Line and 15 along the AK Steel northern fence line).






Routine quarterly sampling ofMW-27 A.

Geo probe groundwater samples collected from locations on Lear property (100 samples collected from 34 locations al approximate depths of 30 ft bgs, 50 ft bgs, and from just above the top of bedrock).

September and December 2010 and March Routine quarterly sampling ofMW-27 A 2011 June 14, 2011

September 27, 2011

December 14, 2011

March and June 2012

September 26, 2012

Routine qumterly sampling ofMW-27 A.




Routine quarterly sampling ofMW-27 A

Soil sample numbering is based on the following general rule

U9GP-01.10 equates to

U9-SWMU9

GP - Geoprobe Sample

01-BoringNo.1

.10 - sample depth 10 feet

Samples Collected Result

None Not applicable.

U4GP-01 (.02, .04, .10 & .27); U6GP-01 (.02, .04 & .10); U6GP-02 (.02, .04, .10, & .27); U6GP-03 (.02, .04, & .10); U6GP-04 (.02, Hexavalent chromium detected in 5 of the 37 samples at concentrations .04, & .10); U9GP-0J (.02, .04, .10, & .27); U9GP-02 (.02, .04, .10, & .27); U9GP-03 (.02, .04, & .10); U9GP-04 (.02, .04, & .10); ranging from 0.94 to 6.7 mg/kg (EPA SSL is 38 mg/kg). UI0GP-01 (.02, .04, .10, & .21); and Ul0GP-02 (.02 & .04)

MW-27A

MW-27A

MW-27A

MW-27A

MW-27A

MW-27A

MW-27A

MW-27A

:tvIW-27A

MW-27A

MW-27A

Hexavalent chromium not detected.

Hexavalent chromium detected in MW-27 A for the first time at a concentration equal to the RSL at 0.11 mg/L.

Hexavalent chromium detected at 0.02 mg/L.

Hexava\ent chromium not detected.

Hexavalent chromium detected above the RSL at a concentration of0.15 mg/L.




Hexavalent chromium detected at 2.4 mg/L (peak concentration detected).

Hexavalent chromium detected at 1.4 mgn •.

Hexavalent chrornilllll detected at .57 mg/L.

LPGW-A3.30; A9.32; B1.30; BS.30; Cl.30; C3.30; CS.30; C7.30; C9.30; Dl.30; D4.30; D6.30; D8.30; El .30; £3.30; E4 (.30, .50, Hexavalent chromium detected in five of20 samples at concentrations & .70); ES (.30 & .50); F2.30, F4.30; GI (.30, .50, & .70); and G3.30. ranging from 0.02 to 0.64 mg/L.

MW-27A

:MW-27A

Lear property [LPGW-GS(.30, .50, & .70); H2 (.30, .50, & .70); H4 (.30, .50, & .70); II (.30, .50, & .70); 13 (.30, .50, & .70); and 15 (.30, .50, & .70)] AK Steel property [APGW-01 (.30, .50, & .70); 02 (.30, .50, & .70); 03 (.30, .50, & .70); 04 (.30, .50, & .70); and 05 (.30, .50, & .70)]

U9GP-05 (.02, .04 & .10); U9GP-06 (.02, .04 & .10); U9GP-07 (.02, .04 & .10); U9GP-08 (.10 & .15); CSAGP-02 (.02, .05, .10, .15, .20, & .24); CSAGP-04 (.02, .05, .10, .15, .20, & .24); CSAGP-05 (.02, .05, .10, .15, .20, & .24); CSAGP-06 (.02, .05, .10, .15, & .20); CSAGP-07 (.02, .05, .10, .15, .20, & .25); CSAGP-08 (.02, .05, .10, .15, .20, & .25) andCSAGP-09 (.02, .05, .10, .15, .20, & .25) Groundwater Samples: CSAGP-01.30, CSAGP-02.30, CSAGP-03.30, CSAGP-04.30, CSAGP-05.30, CSAGP-06.30, CSAGP-07.30, CSAGP-08.30, and CSAGP-09.30

U9GP-09.33

U9GP-10, U9GP-l l, and U9-GPl2

Hexavalent chromium detected at .08 mg/L.

Hexavalent chromilllll detected at .04 mg/L.

Hexavalent chromium detected in seven of27 Lear property samples at concentrations ranging from 0.11 to 0.63 mg/L. Hexavalent chromium detected in one of 15 samples from AK Steel property at an estimated concentration of0.006 mg/L.

SWMU 9; hexavalenl chromium detected in three of 11 samples at concentrations ranging from 3.3 to 26.8 mg/kg; CSA: hexavalent chromium detected in eitght of53 samples at concentrations ranging from 0.95 mg/kg to 11.5 mg/kg (EPA SSL is 38 mg/kg) Hexavalent chromium not detected in groundwater.

Hexavalent chromium detected below the RSL at estimated concentration of 0.03 mg/L.

Hexavalcnt chromium not detected.

ACSGP-01 (.30 & .70); 05 (.30 &,.70); 06 (.30 & .70); 07 (.30 & .70); 08 (.30 & .70): 09 (.30 & .70); 10 (.30 & .70); 11 (.30 & .70); Hexavalent chromium not detected. 12 (.30 & .70); 13 (.30 & .70); 14 (.30 & .70); 15 (.30 & .70); 16 {.30 & .70); 17 (.30 & .70); 18 (.30 & .70); and 19 (.30 & .70)

MW-27A

MW-27A

MW-27A

MW-27A

MW-27A

MW-27A

GPI0-Bl (.30 . .50, & .75); B2 (.30, .50, & .76); B3 (.38, 58, & .73); Cl (.30, 50, & .74); C2, (.30, .50, & .73); C3 (.30, .50, & .77); C4 (.38, .58, & .83); DI (.30, .50, & .72); D2 (.30, .50, & .76); D3 (.33, .58, & .76); D4 (.35, .55, & .80): D5 (.38, .58, & .83); El.71; E2 (.30, .50, & .72); E3 (.36, .56, & .83); E4 (.35, .55, & .80); E5 (.37, .57, & .82); E6 (.36, .56, & .81); E7 (.38, .58., & .83); E8 (.42, .62, & .87); F3 (.30, .50, & .77); F4 (.33, .53, & .88); F5 (.36, .56, & .81); F6 (.36, .56, & .81); F7 (.38, .58, & .83); F8 (.38, .58, & .83); F9 (.41, .61, & .86); GJ (.30, .50, & .72); G6 (.36, .56, & .81); G7 (.37, .57, & .82); GS (.37, .57, & .82); G9 (.38, .58, &

.83); GlO (.37, .57, & .82); and Gl 1 (.41, .61, & .86)

MW-27A

MW-27A

MW-27A

MW-27A

MW-27A

MW-27A


HexavaJent chromimn detected above the RSL at 0.18 mg/L.

Hexavalent chromium detected above the RSL at 0.24 mg/L.

Hexavalent chromium detected above the RSL at 0. 14 mg/L.

Hexavalcnt chromium not detected.


Hexavalent chromium detected in 7 samples from 6 of34 locations at 0.003 to 0.18 mg/L (locations disassociated and it is concluded no discemable plume present).

Hexavalent chromimn detected at estimated concentrations ranging from 0.003 to 0.005 mg/L. Hexavalent chromium not detected.

Hexavalent chromium detected above the RSL at 0.17 mg/L.


Hexavalent chromium detected below the RSL in both samples at 0.051 mg/L.

Hexavalent chromium detected below the RSL at estimated concentration of 0.098 mg!L.

K:\CCA\PROJECTS\AKZancsville\Final Report 30!3 Order Rev. 2\Final Modification.s\Table 1 Hexavalent Chromium Timdinc.qpw

Cox-Colvin Et: Associates, lnc.

Table 2. Hexavalent Chromium Concentrations in Groundwater from Monitor Well MW-27 A (May 2010 to September 2012), AK Steel Corporation-Zanesville Works, Zanesville, Ohio

I Samele Date

05/05/10

09/01/10

12/01/10

03/23/11

06/14/11

09/27/11

12/14/11

03/08/12

06/13/12

09/26/12

J - estimated value U - undetected < - undetected

I Detected

No

Yes

Yes

Yes

No

Yes

No

Yes

Yes

Yes

I Result I 0.003 UJ

0.005

0.005

0.003

<0.02

0.17

<0.02

0.051

0.051

0 .0098 J

Units I MG/L

MG/L

MG/L

MG/L

MG/L

MG/L

MG/L

MG/L

MG/L

MG/L

K:\CCA\PROJECTS\AKZanesville\Final Report 3013 Order Rev. 2\Final Modifications\hex Cr Results MW-27 A.qpw

Cox-Colvin Et Associates, lnc.

Concentrations (IVIG/L) Parameter: Hexavalent Chromium Original Data (Not Transformed) Non-Detects Replaced with Detection Limit Total Measurements: 10 Total Non-Detect: 3 Percent Non-Detects: 30% Total Background Measurements: 0 There are O background locations

Loe. Meas. ND Date Cone. Original

There is 1 compliance location


MW-27A 10 3 (30%) 5/5/2010 ND<0.003 ND<0.003 9/1/2010 0.005 0.005 12/1/2010 0.005 0.005 3/23/2011 0.003 0.003 6/14/2011 ND<0.02 ND<0.02 9/27/2011 0.17 0.17 12/14/2011 ND<0.02 ND<0.02 3/8/2012 0.051 0.051 6/13/2012 0.051 0.051 9/26/2012 0.0098 0.0098

There are O unused locations . --


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Sen's Slope Analysis Parameter: Hexavalent Chromium Location: MW-27A Original Data (Not Transformed) Non-Detects Replaced w ith Detection Limit

90% Confidence Level

Xj XI< (Xj • Xl<)/(j-k) Q 0.005 (9/1/2010) ND<0.003 (5/5/2010) (0.005- 0.003)/(2 -1) 0.002 0.005 (12/1/2010) ND<0.003 (5/5/2010) (0.005 - 0.003)/(3 - 1) 0.001 0.003 (3/23/2011) ND<0.003 (5/5/2010) (0.003 - 0.003)/(4 - 1) 0 ND<0.02 (6/14/2011) ND<0.003 (5/5/2010) (0.02 - 0.003)/(5 - 1) 0.00425 0.17 (9/27/2011) ND<0.003 (5/5/2010) (0.17 - 0.003)/(6 - 1) 0.0334 ND<0.02 (12/14/2011) ND<0.003 (5/5/2010) (0.02 - 0.003)/(7 - 1) 0.00283333 0.051 (3/8/2012) ND<0.003 (5/5/2010) (0.051 - 0.003)/(8 - 1) 0.00685714 0.051 (6/13/2012) ND<0.003 (5/5/2010) (0.051 - 0.003)/(9 - 1) 0.006 0.0098 (9/26/2012) ND<0.003 (5/5/2010) (0.0098 - 0.003)/(10 - 1) 0.000755556

0.005 (12/1/2010) 0.005 (9/1/2010) (0.005 - 0.005)/(3 - 2) 0 0.003 (3/23/2011) 0.005 (9/1/2010) (0.003 · 0.005)/(4 - 2) -0.001 ND<0.02 (6/14/2011) 0.005 (9/1/2010) (0.02 - 0.005)/(5 - 2) 0.005 0.17 (9/27/2011) 0.005 (9/1/2010) (0.17 • 0.005)/(6 • 2) 0.04125 ND<0.02 (12/14/2011) 0.005 (9/1/2010) (0.02 • 0.005)/(7 - 2) 0.003 0.051 (3/8/2012) 0.005 (9/1/2010) (0.051 - 0.005)/(8 - 2) 0.00766667 0.051 (6/13/2012) 0.005 (9/1/2010) (0.051 - 0.005)/(9 - 2) 0.00657143 0.0098 (9/26/2012) 0.005 (9/1/2010) (0.0098 - 0.005)/(10 • 2) 0.0006

0.003 (3/23/2011) 0.005 (12/1/2010) (0.003 - 0.005)/(4 • 3) -0.002 ND<0.02 (6/14/2011) 0.005 (12/1/2010) (0.02 - 0.005)/(5 - 3) 0.0075 0.17 (9/27/2011) 0.005 (12/1/2010) (0.17 - 0.005)/(6 - 3) 0.055 ND<0.02 (12/14/2011) 0.005 (12/1/2010) (0.02 - 0.005)/(7 • 3) 0.00375 0.051 (3/8/2012) 0.005 (12/1/2010) (0.051 - 0.005)/(8 - 3) 0.0092 0.051 (6/13/2012) 0.005 (12/1/2010) (0.051 • 0.005)/(9 • 3) 0.00766667 0.0098 (9/26/2012) 0.005 (12/1/2010) (0.0098 - 0.005)/(10 - 3) 0.000685714

ND<0.02 (6/14/2011) 0.003 (3/23/2011) (0.02 - 0.003)/(5 · 4) 0.017 0.17 (9/27/2011) 0.003 (3/23/2011) (0.17 - 0.003)/(6 - 4) 0.0835 ND<0.02 (12/14/2011) 0.003 (3/23/2011) (0.02 - 0.003)/(7 · 4) 0.00566667 0.051 (3/8/2012) 0.003 (3/23/2011) (0.051 - 0.003)/(8 - 4) 0.012 0.051 (6/13/2012) 0.003 (3/23/2011) (0.051 - 0.003)/(9 - 4) 0.0096 0.0098 (9/26/2012) 0.003 (3/23/2011) (0.0098 - 0.003)/(10 - 4) 0.00113333

0.17 (9/27/2011) ND<0.02 (6/14/2011) (0.17 - 0.02)/(6 - 5) 0.15 ND<0.02 (12/14/2011) ND<0.02 (6/14/2011) (0.02 - 0.02)/(7 - 5) 0 0.051 (3/8/2012) ND<0.02 (6/14/2011) (0.051 - 0.02)/(8 - 5) 0.0103333 0.051 (6/13/2012) ND<0.02 (6/14/2011) (0.051 - 0.02)/(9 - 5) 0.00775 0.0098 (9/26/2012) ND<0.02 (6/14/2011) (0.0098 - 0.02)/(10 - 5) -0.00204

ND<0.02 (12/14/2011) 0.17 (9/27/2011) (0.02 - 0.17)/(7 - 6) -0.15 0.051 (3/8/2012) 0.17 (9/27/2011) (0.051 - 0.17)/(8 - 6) -0.0595 0.051 (6/13/2012) 0.17 (9/27/2011) (0.051 -0.17)/(9-6) -0.0396667 0.0098 (9/26/2012) 0.17 (9/27/2011) (0.0098 - 0.17)/(10 - 6) -0.04005

0.051 (3/8/2012) ND<0.02 (12/14/2011) (0.051 - 0.02)/(8 - 7) 0.031 0.051 (6/13/2012) ND<0.02 (12/14/2011) (0.051 - 0.02)/(9 - 7) 0.0155 0.0098 (9/26/2012) ND<0.02 (12/14/2011) (0.0098 - 0.02)/(10 - 7) -0.0034

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0.051 (6/13/2012) 0.0098 (9/26/2012)

0.0098 (9/26/2012)

Number of Q values = 45

Ordered Q Values n Q 1 -0.15 2 -0.0595 3 -0.0412 4 -0.04005 5 -0.0396667 6 -0.0206 7 -0,0034 8 -0.00204 9 -0.002 10 -0.001 11 0 12 0 13 0 14 0 15 0.0006 16 0.000685714 17 0.000755556 18 0.001 19 0.00113333 20 0.002 21 0.00283333 22 0.003 23 0,00375 24 0.00425 25 0.005 26 0.00566667 27 0.006 28 0.00657143 29 0.00685714 30 0.0075 31 0.00766667 32 0.00766667 33 0.00775 34 0.0092 35 0.0096 36 0.0103333 37 0.012 38 0.0155 39 0.017 40 0.031 41 0.0334 42 0.04125 43 0.055 44 0.0835 45 0.15

0.051 (3/8/2012) 0.051 (3/8/2012)

0.051 (6/13/2012)

Sen's Estimator (Median Q) Is 0.00375

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(0.051 - 0.051)/(9 - 8) (0.0098 - 0.051)/(10 - 8)

(0.0098 - 0.051)/(10 - 9)

0 -0.0206

-0.0412

Tied Group 1 2 3 4

Time Period 5/5/2010 9/1/2010 12/1/2010 3/23/2011 6/14/2011 9/27/2011 12/14/2011 3/8/2012 6/13/2012 9/26/2012

Value 0.003 0.005 0.02 0.051

Members 2 2 2 2

Observations 1 1 1 1 1 1 1 1 1 1

There are 0 time periods with multiple data

A=72 B=0 C=0 D=0 E=8 F=0 a= 2250 b = 6480 C = 180 Group Variance= 121 For 90% confidence interval (two-tailed), Z at (1-0.9)/2 = 1.64485 C = 18.0934 M1 = (45-18.0934)/2.0 = 13.4533 M2 = (45 + 18.0934)/2.0 + 1 = 32.5467 Lower limit is 0 = Q(13) Upper limit is 0.00775 = Q(33) 0 < 0 < 0.00775 indicating no trend in data.

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AK STEEL LETTER RE: ADDENDUM TO REVISION 2 OF THE 3013 ...

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