Notes/Deficiencies, ADM Class VI Permit Application, Section 2 – Hydrogeology

2.2 Faults, Known or Suspected Within the Area of Review

“Newly acquired 3D seismic data has already been acquired at the proposed ICCS site and is currently

being processed.”  Please provide this information as soon as it is available.

2.3 Maps and Cross Sections

This section mentions that a “site elevation is approximately 660 feet.”  If this is the well site, why is it

not 675 feet above MSL as mentioned in section 2.1?  If this is a different site, please clarify in the text.

2.4.3.3 Fracture Pressure at the Top of the Injection Zone

What was the reason that the fracture pressure test was only run on the lower portion of the

completion interval and not the entire perforated interval?

Please explain how changes in downhole density due to the compressibility of CO2 were considered.  

What values for injectate density were used?

2.4.3.4 Effective Porosity

Please define effective porosity and how it differs from bulk porosity (to which it was compared), and

describe how effective porosity was determined.   

Will injection be effected by residual water saturation?  Also see related topic in 2.4.3.7.

Table 2‐1 – Please explain in more detail the methodology for the placement of the divisions between

sub‐intervals.

2.4.3.5 Intrinsic Permeability ‐ Core Analysis

Please state the origin of the value for m used in Archie’s equation.

Please give all values used in Archie’s equation, and how this calculation determined grain size.

Please explain why the interval 6,650‐6,820 has a higher average porosity, yet significantly lower

average permeability, than the interval immediately below (6,820‐7,050).

2.4.3.5 Intrinsic Permeability ‐ Well Testing

“After this test, these perforations were acidized and a step‐rate test was conducted.  For the second

step‐rate test, treated water was injected at 3.1 bpm (130 gpm) for five hours, while pressure was

monitored for approximately 45 hours.”  It is possible that the underlined “step‐rate test” should read

“pressure falloff (PFO) test”?  If this is so, please make the correction, if not, please explain.

2.4.3.7 Storage Coefficient

It does not appear that residual water saturation was included in calculations – please explain how

residual water saturation will or will not influence the effective porosity, given that this will be a two

phase system (CO2 and brine).

Why was the entire thickness (1,506’) of Mt. Simon and an average porosity of 10% used for calculation?  

Was the average porosity used that of bulk porosity or effective porosity?  Why was 10% used, but a

value of 13.2% given in Table 2‐3?

2.4.3.8 Seepage Velocity and Flow Direction of Formation Water

Please cite evidence and supporting references of the slow flow rate in the Mt. Simon.

2.4.4 Characteristics of Injection Zone Formation Water

Please support the description of reservoir fluid samples as “high quality.”
2.4.4.5 Total Dissolved Solids

Please explain the difference in values for TDS given in paragraph two of this section (higher) compared

to the values given for the area in Figure 2‐19 (lower).

2.5 Upper Confining Zone

Please provide a reference for data from the Manlove Gas Storage Field.

2.5.1 Geologic Names of Confining Zone

According to Figure 2‐8, shale is not the lowermost section in the Eau Claire.  Please explain.

2.5.3.1 Lithologic Description

Comments were received to suggest that the Eau Claire becomes a mixture of dolomite and limestone

with some fine‐grained siliciclastics far south of the proposed injection site.  Please amend to clarify the

distance from the injection site where this change takes place.

2.5.3.5 Alternative Confining Zones Proposed

For the statement “The Ordovician‐age Maquoketa Shale is 206 feet thick at the CCS #1 well site with

the top at a depth of 2,611 feet below.” it is assumed that the reference datum is implied to be 2,611

feet below ground surface.  Please amend to clarify.

2.5.5.3 Intrinsic Permeability

Were permeability values determined on the small shale samples from the core plugs or cuttings?  If

they were, please supply these values.  If not, why were they not determined?

2.7 Overlying Sources of Groundwater at the Site

The lowermost USDW should be stated as a formation name with an associated depth, as well as

measurements obtained above and below the threshold to justify the statement.  

If reference to letters from Frommelt and Nightingale continue to be used, please provide a copy of such

letters.

2.7.1.4 Lithology

Much of the information presented in this section appears to be stated as such in the northern part of

Illinois.  If it is also applicable to central Illinois, please explicitly state this.

2.7.2.1 Maps and Cross Sections – Mississippian Bedrock

In the statement “They noted that mineralization of groundwater in the Valmeyeran and Chesterian

units of the Mississippian System...” to whom does “they” refer?

For the statement “Groundwater with low TDS occurs only in and near....” it is assumed low TDS is

<10,000 mg/L.  Please amend to clarify.

General Questions

The Class VI regulations also ask for: (146.82) (6) Baseline geochemical data on subsurface formations,

including all USDWs in the area of review.   

Permit application section 2.7 has little more than mention of TDS in aquifers.  At some point prior to

injection, it is critical to obtain and list accurate values for many geochemical parameters such as pH,
alkalinity, Fe, Ca, Mg, Na, etc. prior to injection.  Any potential change in geochemical parameters after

injection would need good baseline data for comparison.

Please include some discussion about flow of dense fluid CO2 in the Mt. Simon – is this different

compared to brine?  Include parameters such as relative permeability, hydraulic conductivity, storage

capacity, etc.

Figures

2‐32 – Please add an index map to show the location of the Line as located on the study site.

2‐33 – Please resize figure if possible.  Much detail is lost at this resolution.

2‐34 – Please indicate the proposed injection site on this figure.

Please include a map displaying the coal mines and oil fields within the area of review.

Please include a large‐scale map showing all relevant features within the area of review (existing wells,

proposed wells, plugged wells, faults, coal mines, oil fields, surface water features, etc.)

Additional Information

From discussions with the United States Geological Survey, additional helpful information on regional

hydrogeology may be available in the following sources:

Pumpage effects in Ironton-Galesville in Chicago region: 

Avery, C., 1995, Reversal of declining ground-water levels in the Chicago area, U.S. Geological Survey 

Fact Sheet 222-95. 

Upward flow gradients in the Mt Simon aquifer: 

Nicholas, J.R., Sherrill, M.G., and Young, H.L., 1987, Hydrogeology of the Cambrian-Ordovician Aquifer 

System at a Test well in Northeastern Illinois, U.S. Geological Survey Open-File Report 84-4165. 

Recent groundwater modeling reports in the Great Lakes region likely provide useful data and 

understanding of flow in the deep bedrock aquifers of the region: 

Meyer, S.C., Roadcap, G.S., Lin, Yu-Feng, Walker, D.D., 2009, Kane County Water Resources 

Investigations: Simulation of groundwater flow in Kane County and northeastern Illinois: Illinois State 

Water Survey Cooperative Report 2009-07. 

Feinstein, D.T., Hunt, R.J., and Reeves, H.W., 2010, Regional groundwater-flow model of the Lake 

Michigan Basin in support of Great Lakes Basin water availability and use studies: U.S. Geological 

Survey Scientific Investigations Report 2010-5109. 

Lampe, D.C., 2009, Hydrogeologic framework of bedrock units and initial salinity distribution for a 

simulation of groundwater flow for the Lake Michigan Basin: U.S. Geological Survey Scientific 

Investigations Report 2009-5060. 
Notes/Deficiencies, ADM Class VI Permit Application, Section 5 – Area of Review

Page 5‐1

5.2 Method of Radius Determination: The text says “... the boundary of the AoR was extended to the

green line inscribing the blue polygon” but it appears to actually circumscribe the blue polygon.  Please

verify and amend if necessary.

Page 5‐2

5.4.1 Simulation Software Description and General Assumptions:  

Please clarify the name of the module – COSTORE or CO2STORE.  The validation, verification and

calibration of the software and model must be documented.

Please describe how the Redlich‐Kwong equation of state was “tuned and modified”.

“Initial simulation‐based estimates ....” Please document this assertion.

Please explain how the software optimizes time step duration.

5.4.2 Site Specific Assumptions and Methodology

Please provide details on the development of the petrophysical and transport properties – “... based on

the interpreted well log data and analysis of core samples ...”  

Page 5‐3

Please provide more detail on the decision that the low‐porosity, low‐permeability interval will be a

flow‐limiting barrier to the CO2.

Is permeability the same in vertical and horizontal directions within a given layer?

For Figure 5‐4, please add a legend explaining the meaning of the colors.

Page 5‐4

Fig. 5‐5 needs to have a more complete caption: please state what the four curves represent.

Fig. 5‐6:  It would have been useful if the information about the meaning of Pc(1), Pc(2), etc. found on

page 5‐4 had been included in the captions for this figure.  Please also define Sw.

Please cite the source of the fracture gradient of 0.715 psi/ft.

Please explain the reasoning behind the 80% and 90% values in the last sentence of the second

paragraph.

5.4.3 Simulation Results

Note that the captions for figures 5‐16 – 5‐21 indicate that the pressure front is shown on the figures, as

does the legend in the upper right corner.  However, there is no white line pressure front shown.  Based

on Fig. 5‐23 the pressure front area has declined to zero.  This should be noted in the figure captions.
Page 5‐6

Geochemical modeling:  The final paragraph states that there will be geochemical reaction of CO2 with

the Eau Claire Formation: how is this possible if the CO2 never leaves the Mt. Simon, as stated in the first

paragraph on this page?

Page 5‐7

5.5.1 Tabulation of Well Data: Within the AoR, final paragraph it is stated that the water table is

generally expected to reflect the ground surface and shallow groundwater is expected to flow east and

southeast.  Please cite references to support these statements for this location.

Page 5‐8

5.6 Area of Review Re‐Evaluation & Corrective Action Plan

First paragraph: discrepancies between predictions and observations can also be due to faulty modeling.  

This should be included as an additional possibility.

Re‐Evaluation Report: The Class VI regulations at §146.91 require the original area of review evaluation

to be retained throughout the life of the project and for 10 years following site closure.  EPA Region 5

policy will be to apply this requirement to subsequent area of review re‐evaluations.