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BEFORE THE PUBLIC UTILITIES COMMISSION
OF THE STATE OF CALIFORNIA
Application of California-American Water
Company (U210W) for Approval of the
Monterey Peninsula Water Supply Project and
Authorization to Recover All Present and Future
Costs in Rates.
Application 12-04-019
(Filed April 23, 2012)
REBUTTAL TESTIMONY OF PETER M. LEFFLER, P.G., C.HG
Sarah Leeper
Nicholas A. Subias
Cathy Hongola-Baptista
California-American Water Company
555 Montgomery Street, Suite 816
San Francisco, CA 94111
Telephone: 415.863.2960
Facsimile:415.397.1586
[email protected] Attorneys for Applicant California-American Water Company
Lori Anne Dolqueist
Nossaman LLP
50 California Street, 34th
Floor
San Francisco, CA 94111
Telephone: 415.398.3600
Facsimile: 415.398.2438
Attorneys for Applicant California-American
Water Company
Dated: October 13, 2017
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TABLE OF CONTENTS
I. INTRODUCTION ....................................................................................................... 1
II. PURPOSE OF TESTIMONY ...................................................................................... 1
III. REBUTTAL TO DR. ABRAMS’ TESTIMONY ....................................................... 2
IV. REBUTTAL TO CURTIS HOPKINS’ TESTIMONY ............................................... 8
V. REBUTTAL TO TESTIMONY OF KEITH VAN DETER MAATEN ................... 15
VI. REBUTTAL TO TESTIMONY OF VERA NELSON ............................................. 19
VII. REBUTTAL TO TESTIMONY OF DR. KNIGHT .................................................. 25
{00412785;1} 1
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BEFORE THE PUBLIC UTILITIES COMMISSION
OF THE STATE OF CALIFORNIA
Application of California-American Water
Company (U210W) for Approval of the
Monterey Peninsula Water Supply Project and
Authorization to Recover All Present and Future
Costs in Rates.
Application 12-04-019
(Filed April 23, 2012)
REBUTTAL TESTIMONY OF PETER M. LEFFLER, P.G., C.HG
I. INTRODUCTION
Q1. Please provide your name and business address.
A1. My name is Peter M. Leffler. My business address is 505 14th
Street, Suite 945, Oakland,
California 94612.
Q2. By whom are you employed and in what capacity?
A2. I am a Principal Hydrologist at Luhdorff & Scalmanini Consulting Engineers.
Q3. Have you previously supplied your qualifications in this proceeding?
A3. Yes, I provided my qualifications in my Direct Testimony in this proceeding, which was
served on March 8, 2013, and updated in my Rebuttal Testimony served on March 22,
2016.
Q4. Are there any changes to your qualifications?
A4. No.
II. PURPOSE OF TESTIMONY
Q5. What is the purpose of your testimony?
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A5. I offer this rebuttal testimony on behalf of California American Water Company
(“California American Water”) to respond to certain issues in the testimony and reports
submitted by Dr. Robert Abrams, Curtis Hopkins, Keith Van Der Maaten, Vera Nelson,
and Dr. Rosemary Knight. I note that large portions of the testimony and reports to
which I am responding are identical, or nearly identical, to that which was submitted in
response to the Draft Environmental Impact Report/Environmental Impact Statement
(“DEIR/EIS”). I understand the California Public Utilities Commission’s (“CPUC”) own
experts are analyzing and will respond to those issues in due course through the EIR
process. I believe those large portions of testimony to be outside the list of topics
identified in the Assigned Commissioner and Administrative Law Judge’s (“ALJ”)
August 28, 2017 Ruling, and I understand California American Water has moved to
exclude that testimony. In the event the Commissioner and ALJ opt to address or
consider those issues from the large portions of testimony in this proceeding that
California American Water has moved to exclude, I provide some limited rebuttal
testimony, but could also furnish additional testimony, if necessary, depending on the
extent to which the Commission and ALJ may decide to consider those issues California
American Water moved to exclude.
III. REBUTTAL TO DR. ABRAMS’ TESTIMONY
Q6. Did you review the Prepared Direct Testimony of Dr. Robert Abrams for the City of
Marina, including the attached March 27, 2017 Memorandum identified as “Comments
on behalf of the City of Marina regarding the Draft EIR/EIS Monterey Peninsula Water
Supply Project, Monterey County, California,” which together are identified as Exhibit
MNA-3?
A6. Yes.
Q7. Do you agree with Dr. Abrams’ testimony that ongoing seawater intrusion control efforts
in the area could affect the feedwater source area and result in a much greater percentage
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of fresh water entering Monterey Peninsula Water Supply Project (“MPWSP”) slant
wells?
A7. I disagree with Dr. Abrams. Dr. Abrams appears to assert that certain measures that have
been proposed, planned, and/or operated could potentially reverse the direction of
groundwater flow so that landward groundwater would flow in a seaward direction,
changing the makeup of the feed water for the MPWSP. Dr. Abrams offers no support
for these assertions. In fact, he acknowledges that currently, seawater intrusion exists in
the project area and that “groundwater flow directions near the Monterey Bay coast are
oriented landward.” (Ex. MNA-3, at p. 4:6-7.) Monitoring well data show that the Dune
Sand Aquifer and 180-FTE Aquifer in the project area were already severely intruded
with seawater prior to California American Water’s operation of the test slant well. Dr.
Abrams states in his testimony, the “2013 data indicate that the seawater intrusion fronts
are in approximately the same locations they were in 2011.” (Ex. MNA-3, Mar. 27, 2017
Memo at p. 4 of 20.) The current Monterey County Water Resources Agency
(“MCWRA”) seawater intrusion maps, which now include 2015 data, show substantial
inland movement of saline water over the last 5 to 15 years. As documented on the 2015
MCWRA seawater intrusion maps for the 180-Foot and 400-Foot Aquifers, seawater
intrusion in both aquifers has been documented to extend up to five miles inland in the
Marina/Fort Ord area (and even further inland in Salinas Valley proper). This has caused
MCWD to abandon many 180-Foot and 400-Foot Aquifer production wells due to high
salinity, including wells MCWD-1, 2, 3, 4, 5, 6, 7, 8A, and 9. These salted-in/abandoned
MCWD production wells are located within or immediately adjacent to areas of
purported “fresh water” being advocated by Abrams and others (e.g., Hopkins, Knight).
The projects Dr. Abrams references were designed, as he acknowledges elsewhere in his
testimony, with the “primary objective of stopping seawater intrusion.” (Id. at p. 4:30.)
While it remains to be seen if the referenced projects will be able to halt the inland
migration of seawater intrusion over the longer-term, available data (2015 MCWRA
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seawater intrusion maps, MCWRA groundwater contour maps) indicate seawater
intrusion continues to migrate further inland and do not indicate a trend of recovering
water levels that would reverse seawater intrusion. To the extent that a seaward
hydraulic gradient may one day be reestablished in these aquifers, it would still take
many decades from that future date to see substantial improvement in water quality.
Furthermore, the capture zones depicted by Dr. Abrams in Figures 6B and 6C of his
March 27, 2017 TM are not accurate because they do not account for the dramatic effect
of the ocean recharge boundary (which will remain the major source of water to the
wells) that is adjacent to and above the MPWSP slant well screens.
Q8. Do you agree with Dr. Abrams’ testimony that the potential impacts of the MPWSP to
groundwater quality and MCWD water supplies have not been completely and
adequately studied, and that the potential impacts on the 900-Foot Aquifer were not
adequately studied or discussed in the DEIR? Please explain your answer.
A8. I disagree with Dr. Abrams. Although this appears to be an issue addressed in the EIR
process, and is not among the issues to be addressed in this portion of the proceeding, to
the extent Dr. Abrams’ testimony on this issue may be considered, I offer the following
brief response.
Results presented in the DEIR, including the HydroFocus Report in DEIR Appendix E2,
illustrate potential impacts to the 900-Foot Aquifer, the 180- and 400-Foot Aquifers, and
existing groundwater users in the City of Marina. The DEIR includes a determination
that there will be no significant impacts to the 400-Foot Aquifer (from which one would
logically conclude there will be no significant impacts to the 900-Foot Aquifer), and
includes drawdown contour maps (in Appendix E2) that show no contour lines to reflect
impacts to the 900-Foot Aquifer (apparently because any such effects are so small in
magnitude as to be below the minimum contour interval of one foot).
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It should also be noted that the MCWD wells screened in the 180-Foot and 400-Foot
Aquifers (that are reported to be active per Dr. Abrams’ Testimony and March 27, 2017
TM) are located more than four miles inland from the proposed MPWSP wells and inland
of the seawater intrusion front. Accordingly, I do not anticipate that the MCWD wells
will suffer any significant impacts from the proposed MPWSP; in fact, the MPWSP may
have a beneficial effect (retardation) of the seawater intrusion front at the MCWD 180-
Foot and 400-Foot Aquifer well locations shown in Abrams TM Figure 2 (based on
groundwater modeling conducted for the DEIR).
The MCWD 900-Foot Aquifer wells are screened at depths ranging from 900 to 1,950
feet below ground surface (i.e., 650 to 1,600 feet below the bottom of the MPWSP wells)
and are located 1.75 to 3 miles inland from the proposed MPWSP wells. There are also
multiple layers of thick clay layers between the bottom of MPWSP wells and the MCWD
deep aquifer well screens. Given the distance between the MPWSP and MCWD wells,
difference in depth of screen intervals of the wells, and presence of multiple clay layers
between the MPWSP wells and the MCWD well screen intervals, the DEIR finding of no
significant impact to the 400-Foot Aquifer, lack of drawdown in the 900-Foot Aquifer
demonstrated in DEIR Appendix E2, and the lack of impacts to the 400-Foot Aquifer
directly beneath the CEMEX site over the two years of test slant well pumping, there is
no evidence to indicate that the operation of the MPWSP will have detrimental impacts
on MCWD’s wells.
Q9. Do you agree with Dr. Abrams’ assertion that the groundwater models used to assess the
potential impacts of the MPWSP on the 180/400 Foot Aquifer and Monterey Subbasins
are not sufficiently detailed or documented to evaluate potential impacts from the
proposed operation of the MPWSP wells? Please explain your answer.
A9. My understanding is that the specifics of the sufficiency of the modeling is addressed in
the EIR process, and that additional peer review of DEIR groundwater modeling
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conducted by GeoSyntec addresses modeling concerns raised by Dr. Abrams. (See
Review of MCWD Comments on RDEIR, Monterey Peninsula Water Supply Project,
Subsurface Intakes and Groundwater Modeling; Revised Draft, August 30, 2017,
appended hereto as Attachment 1.)
Q10. Do you agree with Dr. Abrams’ assertions that the 180/400-Foot Aquitard is likely
missing and/or the 400-Foot Aquifer in the MPWSP area is likely unconfined?
A10. No. Although this appears to be an issue addressed in the EIR process, and not among
the issues to be addressed in this portion of the proceeding, to the extent Dr. Abrams’
testimony on this issue may be considered, I offer the following brief response.
The MPWSP monitoring well lithologic/geophysical data and test slant well pumping
data show that the 400-Foot Aquifer is confined. Dr. Abrams’ assertions that the 180/400
Foot Aquitard is absent in the project area appears to be based on a selective review of
the evidence resulting in a false conclusion. The data, including the lithologic logs and
geologic cross-sections documented in the Hydrogeologic Working Group’s (“HWG”)
Hydrogeologic Study and Technical Report filed in this matter on October 12, 2017
(“HWG Final Report”), monitoring well water levels, and water level responses to test
slant well pumping documented in weekly and monthly reports posted on the project
website and in the HWG documents, makes clear that the 180/400 Foot Aquitard is in
fact present and the 400-Foot Aquifer is confined in the project area. I also note that Dr.
Abrams’ discussion, in his memorandum appended to his testimony, of possible holes in
the 180/400-Foot Aquitard and potential for corresponding gaps in the Salinas Valley
Aquitard (“SVA”) (for which he provides no evidence), are based on data outside of the
CEMEX project area. More detailed lithologic logging, geophysical logging, and cross-
section preparation conducted as part of HWG efforts show continuity of the 180/400-
Foot aquitard and confinement of the 400-Foot Aquifer in the project area. (See HWG
Final Report.)
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Q11. Do you agree with Dr. Abrams’ contention that Dr. Knight’s preliminary report regarding
her airborne electromagnetic survey provides “clear evidence of freshwater in the upper
aquifer in the Marina Coast area”?
A11. No; I disagree with that contention. First, it is important to note that Dr. Knight’s report
is very preliminary and she states that evaluation of the data will require another six
months of work; therefore, interpretations presented in Dr. Knight’s report cannot be
considered final. That being said, the preliminary profiles (i.e., cross-sections) developed
from surface geophysical data by Professor Knight do not delineate the unsaturated
(vadose) zone, water table, or aquifers and aquitards, so it is not possible to evaluate if
any revised interpretation of the hydrogeology has been developed by Dr. Knight.
Review of the currently available geophysical data (which is limited because field data
collection efforts did not begin until May 2017, well after the DEIR was prepared and
comments submitted) indicates that the surface geophysical data developed by Dr. Knight
is consistent with the existing hydrogeologic conceptual model developed by the HWG
(which is generally incorporated in the DEIR). Several of the cited issues with Dr.
Knight’s work were addressed in the HWG Final Report, which provides a more detailed
interpretation of available surface geophysics data.
There are several issues related to the relevance of the other studies by Dr. Knight (and
her associates) referenced by Dr. Abrams in his March 27, 2017 EIR comment
memorandum1 to the MPWSP. The studies generally do not cover the potential impact
areas from pumping of MPWSP wells, no well control is utilized from the MPWSP area,
these studies are only conducted for a section along the coastline, and lithologic
(aquifer/aquitard delineation) is not provided in these references. Overall, these studies
1 Goebel, Pidlisecky, and Knight, 2017. Resistivity imaging reveals complex pattern of saltwater intrusion along
Monterey Coast. Journal of Hydrology (in press); and Pidlisecky, Mora, Hansen, and Knight, 2016. Electrical
resistivity imaging of seawater intrusion into the Monterey Bay aquifer system. Groundwater, Vol. 54, No. 2, pp.
255-261.
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do not provide substantiated data or information that contradicts the Hydrogeologic
Conceptual Model (“HCM”) developed by the HWG, nor does Dr. Knight’s most recent
preliminary report provide substantiated data or information that contradicts the HCM
developed by the HWG. Dr. Abrams’ reliance on the data from this report in asserting
there is “clear evidence of freshwater in the upper aquifer in the Marina Coast area…
including the seawater intruded area mapped by the MCWRA,” fails to account for
flawed assumptions in the preliminary report, most importantly, the level of dissolved
solids to constitute freshwater. Dr. Abrams’ reliance on Dr. Knight’s report is also
flawed because the definition of fresh water that Dr. Knight uses in her preliminary report
is misleading. Dr. Knight defines fresh water as that with total dissolved solids in
concentrations of 3,000 mg/L or less. The maximum contaminant levels (“MCL”) for
total dissolved solids in potable water are 500 mg/L (recommended) and 1,000 mg/L
(maximum). (See Cal. Code Regs., tit. 22, sec. 64449 (2016).) Indeed, monitoring well
data demonstrates that the TDS values of 1,000 and 1,500 mg/L are typically associated
with chloride values of approximately 250 and 500 mg/L. Such chloride values are
commonly used to define the extent of seawater intrusion, as well as serving as MCLs
(recommended and maximum) for chloride.
IV. REBUTTAL TO CURTIS HOPKINS’ TESTIMONY
Q12. Did you review the Further Direct Testimony of Curtis Hopkins, identified as Exhibit
MCD-55 and his Memorandum regarding the MPWSP return water, dated September 29,
2017, and all of the attachments thereto, including the March 29, 2017 letter from
Hopkins Groundwater Consultants to MCWD, identified as Exhibit MCD-57?
A12. Yes.
Q13. In his Further Direct Testimony, Mr. Hopkins states the purpose of his testimony is to
update HGC’s January 22, 2016 report (identified as Exhibit MCD-20) with new
information, including information from the June 16, 2017 report titled “Preliminary
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Interpretation of SkyTEM Data Acquired in the Marina Coast Water District,” prepared
by Ian Gottschalk and Rosemary Knight, which is identified as Exhibit MCD-51. Have
you reviewed the documents identified as Exhibits MCD-20 and MCD-51?
A13. Yes.
Q14. Mr. Hopkins also addresses the Return Water Settlement Agreement entered among
California American Water and other parties. Have you reviewed the Return Water
Settlement Agreement that Mr. Hopkins refers to in his testimony?
A14. Yes.
Q15. At the outset of his testimony, Mr. Hopkins notes that his report addresses the Return
Water Settlement Agreement entered among certain parties, including California
American Water, asserting it does not address concerns he raised in his prior testimony
regarding the Return Water Settlement Agreement. Do you have any comments on his
report as it relates to the Return Water Settlement Agreement?
A15. Yes. As an initial matter, my understanding is that the Return Water Settlement
Agreement was intended to address issues of compliance with the Agency Act, and not
mitigation or water rights. However, I also understand that Mr. Hopkins raised the
mitigation issue in response to the DEIR and, therefore defer to that process to address
the issue.
However, I do want to address a couple points outlined in his discussion on the Return
Water Settlement Agreement in his report.
First, Mr. Hopkins describes groundwater levels “above sea level” in the 180-Foot
Equivalent (“FTE”) Aquifer during the 2015-2016 winter season being related to
downward recharge from the overlying shallow aquifer. (Ex. MCD-57, at p. 29.) His
discussion on this point is incomplete and misleading for the following reasons: 1) mean
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sea level in terms of the NAVD88 Datum used on monitoring well hydrographs in the
weekly and monthly MPWSP reports is equivalent to approximately +3 feet NAVD –
meaning that 180-FTE Aquifer water levels effectively do not rise above sea level even in
the winter, and 2) to the extent that groundwater elevations in the 180-FTE Aquifer show
a seasonal rise that may very temporarily rise above sea level for only a short time, that
recovery or rise in water levels is primarily related to reduced agricultural and municipal
and overall groundwater recharge throughout the basin pumping during the winter
season.
Second, Mr. Hopkins asserts that “[t]he benefits from these unique groundwater recharge
conditions creating shallow mounding…[which] will be removed by the project…” (Id.)
This statement is inaccurate. To the extent that shallow perched/mounded aquifers
provide any beneficial recharge to the underlying Dune Sand and/or 180-FTE Aquifer
related to seawater intrusion, this process would continue to occur without impacts from
the proposed MPWSP pumping wells due to the distance from the MPWSP pumping and
lack of hydraulic continuity with the zone of project pumping.
Third, Mr. Hopkins contends that water levels in MW-6M and MW-6M(L) demonstrate
vertical recharge in certain areas where aquitard layers are discontinuous. (Id.) This
statement is also inaccurate, because monitoring wells MW-6M and MW-6M(L)
(formerly labeled as MW-6D) are located within the same aquifer (the 180-Foot Aquifer),
and the aquitard layer between the 180-Foot and 400-Foot aquifers is indicated to be
present at the MW-6 monitoring well location.
Fourth, Mr. Hopkins also asserts that “California American Water’s return water proposal
does not address the increased seawater intrusion that the project will cause…by lowering
existing protective heads and removing freshwater in storage.” (Id.) What Mr. Hopkins
is referring to here is water in the perched/mounded aquifer, which will not be impacted
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by proposed project pumping for the following reasons: (1) the area where groundwater
from the perched/mound aquifer percolates into the underlying Dune Sand (or equivalent)
Aquifer or 180-Foot (or 180-FTE) Aquifer is generally located about 1.5 miles inland
(where the FO-SVA pinches out) or further from the coastline and MPWSP wells; (2) the
area described above is inland from the capture zone (i.e., flow paths of ocean water to
the project slant wells) of the MPWSP wells, which means it will not be impacted by
increased salinity; and 3) the Perched/Mounded Aquifer is hydraulically disconnected
from the regional Dune Sand where MPWSP wells are screened. Finally, I must clarify a
point that Mr. Hopkins makes in the introduction to his report regarding the Return Water
Settlement Agreement. Mr. Hopkins states that “California American Water proposes to
return to the SVGB the percentage of the raw water (or feed water) pumped from the
MPWSP intake wells that is determined to be groundwater as opposed to ocean water.”
It is more accurate to state that California American Water proposes to return the fresh
water component of the feed water as determined by the water quality from the project
extraction wells and based on the formula provided in the Settlement Agreement.
Q16. Mr. Hopkins makes several references in his testimony and report to “protective
groundwater levels,” “protective water levels” above seawater that prevent seawater
intrusion in shallower sediments, and the “protective head” or impedance provided by the
freshwater recharge efforts, concluding that unless the return water method ensures that
these protective conditions are not harmed, the MPWSP will induce seawater intrusion
into the Dune Sand Aquifer, will exacerbate seawater intrusion in the 180-Foot Aquifer
and 400-Foot Aquifer, will likely result in cumulative impacts to aquifers and wells much
further inland, and will delay or defeat efforts to reverse the trend of seawater intrusion in
the Northern Marina Subarea. Do you agree?
A16. No. First, it is at best questionable what, if any, protection these groundwater levels and
any alleged freshwater pockets actually provide, given the historic and current extent of
seawater intrusion in the project area. Mr. Hopkins appears to support his position on
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this point by asserting throughout his testimony and report that updated modeling is
necessary to address the data outlined in Dr. Knight’s preliminary report and otherwise
further evaluate the MPWSP’s direct and cumulative impacts on water quality and levels
in each aquifer. I will generally defer to the anticipated findings in the EIR process
regarding the sufficiency of the modeling and the overall DEIR hydrogeologic analysis
related to this issue. However, to the extent any groundwater levels exist that provide
any sort of barrier to seawater intrusion, they occur in the perched/mounded aquifers
greater than 1.5 miles inland as evidenced by geologic mapping and groundwater contour
maps provided in the HWG Final Report and will not be impacted by project pumping
(due to distance and hydraulic discontinuity from the aquifers subject to project pumping
(as further described in my answer to Question 15 above). Additionally, as noted above
and as evidenced in the project DEIR groundwater modeling, operation of the MPWSP
wells will create a zone of beneficial impact (for salinity) that will retard seawater
intrusion inland of the capture zone. This beneficial impact occurs because the pumping
of the MPWSP wells extracts saline water flowing inward from the ocean (that would
occur without the MPWSP) that would otherwise migrate further inland beyond the
MPWSP capture zone in the absence of the MPWSP. In other words, the operation of
the MPWSP will help serve as a partial protective barrier to further seawater intrusion for
a portion of the basin area.
Q17. Mr. Hopkins commits much of his testimony and report to addressing information from
Dr. Knight’s preliminary report regarding whether fresh water is present inland of the
coastline and within the Dune Sand and 180 FTE Aquifer. Do you have a response to
these comments?
A17. In Dr. Knight’s preliminary report, she mischaracterizes the definition of “fresh water.”
Mr. Hopkins adopts this misinterpretation and, as a result, incorrectly analyzes the
potential implications for the MPWSP. Specifically, Dr. Knight defines “fresh water” as
water containing less than 3,000 mg/L of total dissolved solids (“TDS”). Her definition
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is based upon a document titled “EPA Guidance for the Determination of Underground
Sources of Drinking Water,” which was written for regulating the construction of deep
water injunction wells in Indiana and Michigan.2 Traditionally, and more appropriately,
“fresh water” is defined as that with a TDS content of less than 1,000 mg/L (maximum)
or 500 mg/L (recommended). (See Cal. Code Regs., tit. 22, sec. 64449 (2016).) My
review of California American Water monitoring well data also indicates that the TDS
values of 1,000 and 1,500 mg/L are typically associated with chloride values of
approximately 250 mg/L and 500 mg/L, respectively. Such chloride values are
commonly used to define the extent of seawater intrusion, as well as serving as MCLs
(recommended and maximum) for chloride. As Mr. Hopkins contends his testimony
addresses the issue of supply, the definition of fresh water that implies usable water is
most appropriate. Accordingly, Mr. Hopkins’ analysis of the airborne electromagnetic
(“AEM”) data from Dr. Knight’s preliminary report – including all of the figures related
to AEM data, and including those figures addressing locations of “fresh water” and
monitoring well water quality – are all misleading and inaccurate.
Furthermore, the conversion of AEM resistivity values to groundwater TDS in
information and figures provided by Dr. Knight and Mr. Hopkins appears to be incorrect;
the HWG provides a proper correlation between AEM data and groundwater TDS values
(HWG Final Report). Furthermore, Figure 3 in Mr. Hopkins’ report (Ex. MCD-57, p. 6)
and other figures in his testimony showing AEM profiles do not delineate the unsaturated
zone, water table, perched zones, aquifers, or aquitards. These figures further
2
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mischaracterize the extent of fresh water by not distinguishing what may be fresh water
in the unsaturated zone or a shallow perched aquifer that has no significance to regional
groundwater.
Mr. Hopkins reliance on Dr. Knight’s preliminary report, and her incorrect definition of
“fresh groundwater” (and lack of data points) also renders his assertion that the Dune
Sand Aquifer and “shallow aquifer zones” in the 180-400 Foot Aquifer could be used as a
direct source of potable groundwater (id., pp. 11-15) without basis. The Dune Sand
Aquifer has not been historically developed for water supply, likely due to lack of
sufficient quantity of water and poor water quality. For the same reasons, it is unlikely to
be developed for water supply in the future. In addition, the 180-FTE Aquifer in the
project vicinity is also not utilized for water supply due to poor water quality related to
historic seawater intrusion; indeed, the MCWD abandoned several wells in this region for
that reason.
Mr. Hopkins’ discussion on page 12 of his report and in Figures 9 and 10, which purport
to show areas of “fresh water,” within the Dune Sane and 180 FTE Aquifers, are
misleading and inaccurate because they rely on an inappropriate definition of “fresh
water,” lack of data points to support the areas purported to hold “fresh water”, and the
analysis does not reflect data from monitoring well MW-6M(L) and therefore fails to
show the presence of the seawater wedge in the 180-Foot Aquifer at this location.
Mr. Hopkins’ testimony (like Dr. Knight’s preliminary report) also fails to sufficiently
address information necessary to analyze the seawater intrusion, including how
aquifer/aquitard sequences are defined and the fact that seawater intrusion is often
manifested as a wedge (i.e., occurrence of less saline water above more saline water
within a given seawater intruded aquifer).
Q18. Mr. Hopkins also discusses on page 20 of his report his estimates of the TDS
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concentration from the test slant wells during the MPWSP’s production period.” Are his
assumptions here accurate?
A18. No. The TDS concentrations cited by Mr. Hopkins here were those levels prior to the
onset of the long-term pumping test that began on April 22, 2015. Water quality data
from long-term testing indicates TDS concentrations of 26,000 mg/L after one week of
pumping, 27,600 mg/L after three weeks of pumping, and 29,100 mg/L (87% ocean
water) after 1.5 months of pumping. TDS concentrations continued to increase when test
slant well pumping resumed later in 2015 to concentrations greater than 30,000 mg/L and
greater than 90% ocean water. Accordingly, it is expected that project slant wells will
extract greater than 90% ocean water.
Q19. Do you have any further points to add in response to Mr. Hopkins’ testimony or report?
A19. Yes. To the extent that any small “fresh water” pockets may exist in the general area of
seawater intrusion as defined by MCWRA due to aquifer heterogeneities and/or location
of inland pumping centers, it is important to note that any attempt to develop a water
supply from these “fresh water” pockets (by installing production water supply wells)
will quickly result in salting in of the well to the point where it becomes unusable. This
is because the nearby saline water will be quickly drawn in towards the pumping well and
the “fresh water” pocket will become saline.
V. REBUTTAL TO TESTIMONY OF KEITH VAN DETER MAATEN
Q20. Did you review the Direct Testimony of Keith Van Der Maaten submitted on behalf of
MCWD, identified as Exhibit MCD-36?
A20. Yes.
Q21. Did you also review the June 22, 2017 memorandum, drafted by Vera Nelson of EKI
Environment & Water, Inc., which is addressed to MCWD and referenced by Mr. Van
Der Maaten in his testimony regarding “costs,” and identified as Exhibit MCD-47?
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A21. Yes.
Q22. Mr. Van Der Maaten cites Ms. Nelson’s memorandum as purportedly providing a
description of the current status and future plans for remediation efforts at Fort Ord. Do
you have any comments in response to statements in the memorandum?
A22. Yes. Mr. Van Der Maaten provides submits Ms. Nelson’s memorandum purportedly to
explain the other projects for which “millions of dollars [have] already been invested by
MCWD and others,” to support and provide context for his assertion that MCWD is
concerned about costs that MCWD could incur in relation to the MPWSP. Notably,
however, neither Mr. Van Der Maaten nor the memorandum identify exactly for what or
how much MCWD has paid for the projects. Instead, it appears the memorandum is
presented to provide additional comments of EKI relating to the DEIR/EIS, challenging
findings regarding the potential for the MPWSP wells to impact the Dune Sand and 180
Foot Aquifers. (Ex. MCD-47, p. 1.) Although I understand such testimony is to be
addressed in the EIR proceedings, I offer the following in response to assertions in the
memorandum, in the event it for some reason is considered in this portion of the
proceeding.
As an initial matter, Ms. Nelson refers to the A-Aquifer in the Fort Ord area as the Dune
Sand Aquifer. This is incorrect. The HWG has documented that the A-Aquifer is
perched/mounded on the FO-SVA aquitard and is hydraulically distinct from the Dune
Sand Aquifer that occurs west of where the FO-SVA aquitard pinches out (i.e., about 1.5
miles from the coast).
Ms. Nelson also notes that the A-Aquifer and Upper 180-Foot Aquifer in the Fort Ord
area are not used for public water supply or sources of drinking water for either former
Fort Ord or the City of Marina. It is important to note that these aquifers are also outside
of the zone of potential water quality impacts from the MPWSP slant wells.
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Ms. Nelson misleadingly asserts that “data from Fort Ord indicates that seepage from the
Dune Sand Aquifer near Monterey Bay…into the underlying 180-Foot Aquifer has
effectively stopped salt water intrusion in the Upper 180-Foot Aquifer in that area.” (Ex.
MCD-47, p. 4.) Her statement fails to acknowledge that: (1) the presence of sufficient
clay layers to define distinct “Upper” and “Lower” 180-Foot Aquifers that may occur in
portions of the Fort Ord area do not occur in the MPWSP area or inland of the MPWSP
area; and (2) regardless of the presence of such clay layers in the middle of the 180-Foot
Aquifer, seawater intrusion tends to occur in the form of a wedge in any given aquifer, as
water with lower salinity will necessarily sit above water with higher salinity (due to
density differences). A seawater wedge in the 180-Foot Aquifer would result in lower
salinity in the upper portion of the aquifer and higher salinity in the lower portion of the
aquifer, with the net result that it is not possible do develop any portion of the aquifer for
potable water supply.
Ms. Nelson contends that: “This natural barrier appears to have been undermined north
of Fort Ord through groundwater extraction and/or salt water discharges into the Dune
Sand Aquifer at the CEMEX sand mining site, and would likely be further disturbed by
the California American Water Project.” (Id. at p. 5.) This statement is misleading and
inaccurate, with no data or analysis to support the claim. It is not clear what Ms. Nelson
is referring to in referencing “groundwater extraction.” Seawater intrusion has occurred
in this area for many decades prior to operation of the California American Water test
slant well at the CEMEX property, and effects of the test slant well operation have been
shown to not extend beyond MW-4 (as demonstrated by water level data in
weekly/monthly test slant well pumping monitoring reports). I am not aware of any other
groundwater extractions from the Dune Sand Aquifer in this area. It is also not clear
what Ms. Nelson is referring to in her reference to “salt water discharges.” The
Hydrogeologic Working Group Final Report documents that discharges by CEMEX to
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percolation ponds are at salinity concentrations much less than seawater and less than
ambient salinity concentrations in the discharge area adjacent to the ocean (due to the
contribution of groundwater from the CEMEX well to these discharges as explained in
the HWG Final Report). Overall, the hypothetical concept put forth in Ms. Nelson’s
memorandum (and Mr. Hopkins’ supplemental report) that the perched/mounded
groundwater from the A-Aquifer provides some sort of natural barrier to prevent seawater
intrusion is highly questionable given the known extent of historic/current seawater
intrusion in the project area. However, to the extent such a partial barrier exists, the
proposed MPWSP would not impact it, because: (1) the location of the purported barrier
is inland of the MPWSP capture zone and area of water quality impacts, and (2) the
perched/mounded aquifer is not directly hydraulically connected to the Dune Sand
Aquifer to be screened by MPWSP wells.
Ms. Nelson’s assertion that monitoring well clusters MW-5, MW-6, and MW-7, “indicate
that chloride and TDS concentrations in the Dune Sand Aquifer and the Upper 180-Foot
Aquifer meet…criteria as a potential drinking water source,” citing in footnote the State
domestic water chloride standards of 250 and 500 mg/L and TDS standards of 500 and
1,000 mg/L, also requires clarification. (Id. at p. 5.) First, the “Upper 180-Foot Aquifer”
does not exist in this area, there is just a single 180-FTE Aquifer. Second, MW-5S(P) is
not screened in the Dune Sand Aquifer but rather in the perched/mounded 35-Foot
Aquifer and is not relevant to the discussion. Third, the MW-6 cluster includes a well
screen in the upper portion of the 180-Foot Aquifer (MW-6M) and a well screened in the
lower portion of the 180-Foot Aquifer (MW-6M(L)). As a result of a seawater wedge at
this location, water quality in the 180-Foot Aquifer does not meet the cited standards.
Fourth, neither MW-7S nor MW-7M meet the cited standards. Therefore, drinking water
supplies cannot be developed at these locations without desalination.
Although Ms. Nelson also claims that California American Water project “should be held
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to the same standards as remedial actions at Fort Ord” (id. at p. 9), the hydrogeologic and
water quality conditions are very different at the California American Water project
location compared to the Fort Ord remedial action areas. The capture zone area for
MPWSP wells contains unusable highly saline water. The only way to make this water
useable is via desalination, which is what the MPWSP will do.
Ms. Nelson’s broad contention that the MPWSP has potential to “increase salt water
intrusion” is refuted by extensive studies completed for the MPWSP that demonstrate the
area of increased salt water intrusion is limited to the capture zone of MPWSP wells
(generally west of Highway 1, and no more than one mile inland from the coast for the
case of highest pumping rate and lowest gradient) and this area will have unusable highly
brackish water replaced by slightly more saline water. (DEIR, HWG Final Report).
VI. REBUTTAL TO TESTIMONY OF VERA NELSON
Q23. Did you review the Direct Testimony of Vera Nelson submitted on behalf of MCWD,
identified as Exhibit MCD-52?
A23. Yes.
Q24. Did you also review the March 28, 2017 memorandum, drafted by Vera Nelson of EKI
Environment & Water, Inc., which is addressed to MCWD and referenced by Ms. Nelson
in her testimony regarding “costs,” and identified as Exhibit MCD-47?
A24. Yes.
Q25. Ms. Nelson first asserts that the MPWSP has the potential to impact MCWD’s
groundwater recharge projects planned for the Armstrong Ranch Area, which she
contends are in close proximity to the proposed MPWSP slant well intake location.
(Ex. MCD-52, p. 3.) Do you agree with her assertion?
A25. No, I do not. As an initial matter, I note (as Ms. Nelson states in her testimony), that
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MCWD presented this same report as part of its comments in response to the DEIR/EIS;
accordingly, the issues addressed in Ms. Nelson’s testimony should be addressed in that
portion of the proceeding; however, I provide the following responses to Ms. Nelson’s
testimony in the event that her testimony and report are for some reason considered in
this portion of the proceeding.
As reflected in Figure 1 in Ms. Nelson’s report, Armstrong Ranch is located over two
miles inland from the MPWSP wells and over one mile inland from the area of potential
water quality impacts from the MPWSP. As noted in the HWG Final Report, the water
quality impact of the MPWSP will only occur within the capture zone (no more than
about 0.5 to 1 mile inland from the coast). Ms. Nelson’s assertion that the model for this
area predicts “that drawdowns will extend between 1.5 and 4.5 miles inland into
MCWD’s service area” (Ex. MCD-54, p. 2) misrepresents this issue. The extent of
drawdowns does not equate to the extent of potential water quality impacts. Potential
water quality impacts are limited to a much smaller area defined by flow paths of water
particles from the ocean to MPWSP wells (essentially the capture zone), an area
generally limited to west of Highway 1 and at most up to one mile inland (DEIR,
Appendix E2). Areas inland of the capture zone will have neutral to positive impacts
(retardation of seawater intrusion) due to the project pumping as discussed in the DEIR
(section 4.4.5). Accordingly, the MPWSP will not impact the ability of MCWD to
develop recharge projects at Armstrong Ranch.
Q26. Ms. Nelson also testifies that California American Water “mischaracterizes the quality of
groundwater in the Dune Sand Aquifer and 180 Foot Aquifer, through which the slant
wells at the CEMEX site will be screened,” asserting that the salinity levels in the Dune
Sand Aquifer and upper portion of the 180-Foot Aquifer meet State potential drinking
water source criteria. Do you agree with this assertion?
A26. No. Ambient groundwater within the main capture zone area of MPWSP wells has high
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salinity as indicated by California American Water monitoring wells MW-1, 3, and 4.
Elevated chloride concentrations are present at least as far inland (over four miles) as
MW-6M(L), which is screened in the lower portion of the 180-Foot Aquifer and indicates
the presence of a seawater wedge at this location (also supported by MCWRA seawater
intrusion mapping). Review of MPWSP monitoring well water quality data indicates that
monitoring wells with groundwater having TDS in the range of 2,500 to 3,000 mg/L have
chloride concentrations exceeding 1,000 mg/L. For example, MW-5D has TDS of 2,616
mg/L and chloride at 1,168 mg/L. Similarly, MW-7M has TDS at 3,832 mg/L and
chloride at 1,739 mg/L, and MW-9S has TDS at 3,204 mg/L and chloride at 1,199 mg/L.
Drinking water maximum contaminant levels for chloride are 250 mg/L (recommended)
and 500 mg/L (maximum). Review of MPWSP monitoring well data indicates that TDS
levels need to be less than 1,000 to 1,500 mg/L TDS to meeting drinking water standards
for chloride. The State drinking water standards set the maximum contaminant levels for
TDS at 500 mg/L (recommended) and 1,000 mg/L (maximum). In summary,
groundwater with TDS concentrations exceeding approximately 1,000 to 1,500 mg/L will
require desalination to allow use for drinking water.
I also note that Ms. Nelson makes conflicting statements regarding the use of the Dune
Sand and upper 180-Foot Aquifers, asserting at one point in her memorandum that “the
Dune Sand Aquifer and upper 180-Foot Aquifer are an important source of water in the
region,” and at another point asserting that the Dune Sand Aquifer and Upper 180-Foot
Aquifer are not used as a public water supply or sources of drinking water. (Ex. MCD-
54, p. 4.) It is clear the latter statement on this subject is correct – the Dune Sand Aquifer
and 180-Foot Aquifer are not used for drinking water in the project area.
Q27. Ms. Nelson also testifies that California American Water failed to consider data from Fort
Ord or certain data from the MPWSP’s recently installed monitoring well clusters. Do
you agree?
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A27. I do not agree. However, this issue is most appropriately addressed in the EIR process.
Indeed, the DEIR/EIS and associated attachments/references provide extensive
explanation and illustration of project area groundwater conditions. The DEIR/EIS
groundwater characterization is further supplemented by HWG work products, which are
summarized and provided as appendices in the HWG Final Report. Should the
Commissioner and ALJ consider this issue, I offer the following.
Ms. Nelson’s assertion in her memorandum that the MPWSP monitoring wells show a
“Bay-ward gradient” in the Dune Sand Aquifer (Ex. MCD-54, p. 4, and Figure 5, p. 8)
are completely inaccurate. Ms. Nelson’s claim and referenced figure both combine use
of monitoring wells screened in the perched/mounded aquifer with the regional Dune
Sand Aquifer (which includes -2 Foot Aquifer and Perched “A” Aquifer). Mr. Hopkin’s
March 29, 2017 report included a similar inaccurate figure (Figure 6). The HWG TM-2
(included as an appendix to the HWG Final Report) includes groundwater contour maps
of the various aquifers, which have distinct and different groundwater flow patterns
compared to the Perched/Mounded aquifers. (As noted, Ms. Nelson’s comments in the
report questioning the adequacy of the groundwater modeling performed for the
DEIR/EIS are more appropriately addressed in the EIR process. I understand that a draft
technical memorandum prepared by GeoSyntec and dated August 30, 2017 [Attachment
1 hereto] addresses these DEIR/EIS comments, and the EIR team will also prepare
responses to these DEIR comments.)
Q28. Ms. Nelson testifies that maps depicting TDS and chloride concentrations detected in
groundwater samples collected from the Fort Ord and California American Water wells
(specifically MW-5, MW-6, and MW-7) screened in the Dune Sand Aquifer and 180-
Foot Aquifer over the last 10 years show that, outside of the immediate CEMEX Site,
groundwater in these aquifer zones is not brackish. Do you agree?
A28. No. Groundwater within the area described by Ms. Nelson is generally not usable
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without desalination. For example, monitoring well MW-7M, screened in the 180-Foot
Aquifer, has TDS exceeding 3,800 mg/L and chloride exceeding 1,700 mg/L as shown in
Figure 4 of Ms. Nelson’s March 28, 2017 memorandum. (Ex. MCD-47.) Monitoring
well MW-6M(L), which is screened in the lower portion of the 180-Foot Aquifer, has
TDS exceeding 1,800 and chloride exceeding 800 mg/L (not shown on Figure 4 of
Ms. Nelson’s March 28, 2017 memorandum March 28, 2017 memorandum). Shallow
monitoring wells within this area have TDS exceeding 1,000 mg/L and chloride greater
than 250 mg/L, indicating they do not meet drinking water MCLs.
In her memorandum, Ms. Nelson also acknowledges that the HWG TM2 provides
groundwater contour maps for various aquifers in the MPWSP area, but claims these
maps complicate matters by separating the “perched zone” from the “-2 foot aquifer
zone,” “incorrectly implying” groundwater flow is discontinuous between Fort Ord and
the northern portion of MCWD service area. (Ex. MCD-54, p. 7.)
Q29. Ms. Nelson also claims that “No current water quality data exists in the south portion of
these capture zones which may extend into areas where non-saline water current exists”
Do you agree?
A29. No. Regarding the first claim, groundwater contour maps should be made for each
aquifer and should not use wells from different aquifers – using monitoring wells from
different aquifers on the same map provides meaningless information. Regarding the
second claim, there is no statement or implication that groundwater flow is discontinuous
on the maps provided in TM 2; rather there is a large area between Fort Ord and the
MCWD service area lacking well data (and contour lines are not drawn where there is no
data). Regarding the third claim, Ms. Nelson’s statement that “No current water quality
data exists in the south portion of these capture zones which may extend into areas where
non-saline water current exists” (id.) is incorrect. Data from MCWD monitoring wells
located within (or adjacent to) the southern portion of the MPWSP wells capture zone
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show TDS concentrations in the Dune Sand Aquifer and 180-FTE Aquifer generally
exceeding 20,000 mg/L (Fugro West, Marina Coast Water District Seawater Desalination
Project; Initiation of Inland Groundwater Monitoring; Letter Report, December 31,
1996).
Q30. Ms. Nelson also testifies that the construction and operation of the MPWSP’s slant wells
at the CEMEX property will: (i) limit recharge of fresh water from the Dune Sand
Aquifer into the upper 180-Foot Aquifer, (ii) influence the natural hydraulic barrier
created as water from the Dune Sand Aquifer recharges the 180-Foot Aquifer; and
(iii) decrease the existing freshwater zone within a portion of MCWD’s service area and
sphere of influence. Do you agree with this testimony?
A30. No. As outlined in my testimony above, to the extent that shallow perched/mounded
aquifers provide any beneficial recharge to the 180-Foot Aquifer, this process would
continue to occur without impacts from the proposed MPWSP pumping for the same
reasons as outlined above in response to the testimony of Dr. Abrams (i.e., this recharge
process occurs inland of capture zone where water quality impacts may occur and there is
hydraulic discontinuity between source of purported recharge and zone of project
pumping). As also outlined above, the hypothetical concept put forth by Ms. Nelson in
her memoranda (and Mr. Hopkins’ supplemental report) that the perched/mounded
groundwater from the A-Aquifer provides some sort of natural barrier to prevent seawater
intrusion is highly questionable given the known extent of historic/current seawater
intrusion in the project area. However, to the extent such a partial barrier exists, the
proposed MPWSP would not impact it because: (1) the location of the purported barrier
is inland of the MPWSP capture zone and area of water quality impacts, and (2) the
perched/mounded aquifer is not directly hydraulically connected to the Dune Sand
Aquifer to be screened by MPWSP wells. Ms. Nelson’s assertions that the salinity of
groundwater within the Dune Sand Aquifer and 180-Foot Aquifer will increase
immediately inland of these capture zones as saline water is drawn into these areas to
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backfill groundwater that is withdrawn is also incorrect. Seawater intrusion inland of the
capture zone will be retarded by the operation of the MPWSP, as would be expected from
basic hydrogeologic principles and is demonstrated in project DEIR groundwater
modeling and the HWG Final Report. As noted in my testimony above, I also disagree
with Ms. Nelson’s assertions that Dr. Knight’s preliminary report lends any support to
her position.
VII. REBUTTAL TO TESTIMONY OF DR. KNIGHT
Q31. Did you review the Direct Testimony of Rosemary Knight submitted on behalf of
MCWD, and identified as Exhibit MCD-49.
A31. Yes.
Q32. Did you also review the document identified as prepared by Dr. Knight and Ian
Gottshalk, titled “Preliminary Interpretation of SkyTEM Data Acquired in the MCWD,”
dated June 16, 2017, and marked as Exhibit MCD-51?
A32. Yes.
Q33. Dr. Knight testifies that the AEM data she and/or her team collected in May 2017
indicates the presence of a sizeable “lens” of freshwater in the Dune Sand and 180-
Foot/180 FTE Aquifers, where it is otherwise presumed that those areas were fully
intruded with salt water. Do you agree with this conclusion?
A33. No. Dr. Knight’s interpretation of the data is incorrect for a couple of reasons.
First, Dr. Knight’s use of the term “fresh water” is misleading. As noted in my testimony
above, Dr. Knight defines “fresh water” as water containing less than 3,000 mg/L of
TDS. Her definition is based upon a document titled “EPA Guidance for the
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Determination of Underground Sources of Drinking Water,” which was written for
regulating the construction of deep water injunction wells in Indiana and Michigan.3
Traditionally, and more appropriately, “fresh water” is defined as that with a TDS content
of less than 1,000 mg/L (maximum) or 500 mg/L (recommended). (See Cal. Code Regs.,
tit. 22, sec. 64449 (2016).) My review of California American Water monitoring well
data also indicates that the TDS values of 1,000 and 1,500 mg/L are typically associated
with chloride values of approximately 250 mg/L and 500 mg/L, respectively. Such
chloride values are commonly used to define the extent of seawater intrusion, as well as
serving as MCLs (recommended and maximum) for chloride. As Dr. Knight asserts that
her testimony addresses the issues of demand and supply of quality groundwater in the
proposed project area (Ex. MCD-49, p. 2:17-20), the definition of fresh water that implies
usable water is most appropriate.
Second, Dr. Knight’s presumption that a “lens” of freshwater means that the area is not
intruded with seawater is incorrect. Dr. Knight’s conclusion fails to account for the fact
that seawater intrusion is often manifested as a wedge. In a saline intruded aquifer, as the
seawater moves inland, the water with less saline is less dense, and therefore sits above
water with more saline, which is denser. As a result, the seawater intruded aquifer would
present as a wedge and would likely appear in the AEM data as what Dr. Knight
perceives, incorrectly, as a “lens” of fresh water. In other words, the data has been
misrepresented. Ds. Knight’s reference to, “…a presumption that those areas were fully
intruded with salt water” is misleading and inaccurate. Seawater intrusion is generally
3
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defined as having chloride concentrations of 500 mg/L or more in this area, which
constitutes less than three percent seawater. Furthermore, as described above, seawater
intrusion commonly occurs as a wedge with lower salinity water overlying high salinity
water in the same aquifer. Thus, the area mapped at having seawater intrusion does not
equate to the aquifer being “fully intruded with salt water.” Lastly, I note that the
resistivity values/color scheme provided on Dr. Knight’s Figures 8a, 8b, 9a, and 9b do
not appear to properly represent field water quality data; thereby resulting in an
indication of lower groundwater TDS from her geophysical survey data as compared to
actual monitoring well TDS concentrations. The HWG Final Report provides the correct
conversion and interpretation of this data.
Q34. Dr. Knight also testifies that, based on the AEM data, she believes the presumption
concerning salt water intrusion in the Dune Sand and 180-Foot/180 FTE Aquifers appears
to be incorrect. Do you agree with her conclusion?
A34. No, I do not. As I explained above, Dr. Knight and others have misinterpreted the data.
Further evidence includes the fact that water supply wells in this region have been
abandoned due to production of high salinity water, indicating that seawater has intruded
into the aquifers in the region. The wedge effect that occurs in a seawater intruded
aquifer, as I described above, likely explains some of the AEM data points that appear to
indicate the presence of less saline impacted water. However, any effort to extract water
from this area would likely produce brackish water that would require desalination.
Q35. Does this conclude your testimony?
A35. Yes.
Attachment 1
595 Market Street, Suite 610 San Francisco, California 94105
PH 510.836.3034 www.geosyntec.com
REVISED DRAFT 30 Aug 2017 Review of MCWD Comments on RDEIR.docx
DRAFT Techn ica l Memorandum
Date: REVISED DRAFT 30 August 2017
To: Jim Cullem, Monterey Peninsula Regional Water Authority
From: Gordon Thrupp, PhD, PG, CHG, Principal Hydrogeologist
Subject: Review of MCWD Comments on RDEIR Monterey Peninsula Water Supply Project Subsurface Intakes and Groundwater Modeling
Geosyntec Consultants (Geosyntec) was engaged by SPI Membrane Technology Consultants, to review comments prepared on behalf of the Marina Coast Water District (MCWD) on the Revised Draft Enviromental Impact Report (RDEIR, ESA, January 2017) prepared for the CalAm Monterey Peninsula Water Supply Project (MPWSP).
The goal of the review was to specifically address the following comments that relate to groundwater/hydrogeologic conditions and potential impacts of the MPWSP to the groundwater resources:
1) MCWD 29 March 2017 letter pgs 1-4, 7-8, Sections C.1 (pg 50-54) and C.2 pgs 55 -64
2) HGC Comments on pgs 1-8, and comments #23-28, #30, #31, #32, #35, #36, #38, & #39
3) GeoHydros Comments- all
4) EKI Comments- parag #5
5) California Unions for Reliable Energy’s (CURE) Comments concerning the vertical infiltration rates to the source wells at pages 38-41 of their comment letter and the supporting technical memoranda.
A brief summary of my response to the comments is followed specific responses and discussion for each of the comment letters.
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SUMMARY
The comment letters submitted on behalf of MCWD claim the analysis of the potential impacts of the proposed project pumping based on the updated model (NMGWM2016, RDEIR, ESA 2017) is not valid because of problems with the model calibration, reliability, and uncertainty. Updates to the NMGWM (NMGWM2016) include refinement of hydrostratigraphy and aquifer properties that better represent conditions near the proposed project. The detailed CEMEX model was calibrated to the test slant well pumping monitoring data, and resulting changes in aquifer parameter values in the re-calibrated CEMEX model were incorporated in the updated NWGWM. The model extent and properties of the Fort Ord - Salinas Valley Aquitard (FO-SVA) were refined in the NMGWM2016, which was a key recommendation by the Lawrence Berkeley National Laboratory review of the NGWMM2015. The FO-SVA, which hydraulically separates the Dune Sand and 180-foot-equivalent (180-FTE), was added south of the Salinas River in the NMGWM2016 and a transition zone was added where the FO-SVA thins toward the coast (HydroFocus, 2016). The ocean boundary conditions were changed to represent more physically realistic conditions. We agree that groundwater quality (salinity) is locally variable, but detailed characterization of groundwater quality and quantity in the Dune Sand Aquifer is not relevant to the evaluation of feasibility and potential impacts of the project. Moreover, both quality and quantity of groundwater in the Dune Sand varies temporally with rainfall, particularly at local occurrences of perched groundwater. MCWD is correct that the model does not evaluate groundwater quality, but return flow will be based on data (salinity of the pumped water), not modeling. Note however, that a recent geophysical survey along the Monterey Bay Coastline using electrical resistivity tomography (ERT) indicates that while the distribution of saltwater intrusion is variable and complex in portions of the 180-ft and 400-ft Aquifers, the saltwater intrusion is relatively ubiquitous and uniform along the coastal margin within the Upper Alluvium including the Dune Sand Aquifer. The only exception appears to be a prominent area of shallow fresh water within the Fort Ord Dunes approximately 6.3 miles south of the CEMEX Plant that is attributed to recharge from water diverted from storm water ponds (Goebel et al, 2017).
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Including water level data for areas of perched groundwater in the shallow aquifers (Dune Sand and A-Aquifer) is a key reason for the alleged “poor calibration” of the NMGWM2016. Local occurrences of perched groundwater are isolated hydraulically from the regional water table by intervening unsaturated intervals, and MODFLOW does not simulate the flow of groundwater for unsaturated conditions. Some of the groundwater elevations for the A-Aquifer (Dune Sand) near Fort Ord and the County Landfill are associated with perched groundwater that are not hydraulically connected to the regional water table and should not be included in the MODFLOW model. This does not influence the reliability of the model simulations of the proposed project pumping. The comment letters for MCWD include numerous claims that the simplified superposition modeling approach that was used to evaluate potential project impacts is not appropriate and the results are not reliable. However, superposition modeling is a commonly used valid approach that directly estimates the lowering of the groundwater levels associated with proposed pumping. For example, the Arizona Department of Water Resources requires all stresses other than the proposed pumping to be removed from models to evaluate potential impact for permitting of proposed pumping wells. Also, routinely used type-curve analysis of aquifer testing data is superposition modeling. Some of the comments address differences in hydostratigraphy represented in regional Salinas Groundwater Basin model and the NMGWM, and calibration problems associated with assigned initial groundwater levels based the regional model. However, the inaccurate initial heads based on the regional model has no influence on the equilibrium (steady-state) simulations of the proposed project pumping, which apparently was recognized by GeoHydros when they used the calibrated version of the NMGWM2016 to independently run simulations of the proposed project pumping instead of the simplified version used by HydroFocus for the superposition modeling presented in the RDEIR. The claims are incorrect that the model results are not reliable because they do not include the influence of salinity and density on groundwater flow. As is documented in the RDEIR, accounting for variable density as a function of salinity would have negligible influence on the model calculations of potential impacts of the proposed project pumping. Although the NMGWM2016 was not used to evaluate portions of source water that the proposed slant wells would pump, modeling simulations conducted by GeoHydros indicate that the total groundwater portion would decrease to 11% after one year and remain at approximately 10% from
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2 to 32 years. This is generally consistent with previous groundwater modeling with the NMGWM2015 reported in the DEIR, and is within the range of assumed replenishment obligations addressed with the NGWM2016 modeling presented in the RDEIR (0 to 12%). Moreover, the determination of the quantity of return water from the project for the groundwater replenishment obligation will be calculated based on the salinity of the water pumped by the project wells using a formula to calculate the portion of Ocean Water and Inland Fresh Water that was based on a water purchase agreement between MCWD, MCWRA and Cal Am (2010). The replenishment formula is provided in Appendix E2 to the DEIR. As part of the review of the NMGWM2015, LBNL did their own simulations using the model files provided by the CPUC, and compared results of their model results with those presented in Appendix E2 of the DEIR (ESA, 2015). LBNL reported that their model runs closely replicated the results for both the CMEX and Northern Marina Groundwater Model (NMGWM2015) that were presented in Appendix E2 of the Draft E2 of the DEIR. As part of the review of NMGWM2016 GeoHydros obtained the model files and ran their own simulations of the proposed project pumping using the calibrated model boundary conditions instead of the simplified version of the model used by HydroFocus for the superposition modeling approach. The modeled drawdown calculated using the two different modeling approaches are nearly identical (see Attachment 1 to this memorandum). Moreover, the difference between the extent of drawdown calculated using the two approaches are well within the uncertainty considered in the analysis and findings by the RDEIR based on the sensitivity analyses on the model results. Claims that the proposed project pumping would interfere with recharge operations planned at Armstrong Ranch are inconsistent with data and analysis. Claims submitted on behalf of CURE that the RDIER fails to adequately analyze the vertical infiltration rate of ocean water into the sea floor that would be induced by the pumping from proposed slant wells are incorrect. Section 4.5.5.2 (pages 4.5-51 to 53) of the RDEIR presents analysis of the vertical infiltration rate of water into the sea floor. The findings presented by the RDIER are reasonable that the potential for impingement of marine organisms and organic material on the sea floor due to the proposed project pumping is less than significant. The claims on behalf of CURE challenging these finding are technically flawed and unsubstantiated.
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REVIEW OF SECTIONS C.1 AND C.2 OF THE MCWD LETTER Sections C.1 and C.2 of the MCWD letter (29 March 2017) address groundwater analysis and discussion of potential impacts. The MCWD letter indicates that the analysis and characterization of existing groundwater conditions, and evaluation and discussion of potential impacts to groundwater by the proposed project presented by the RDEIR, including the North Marina Groundwater Model (NMGWM) is inadequate. I disagree. The RDEIR and the associated groundwater modeling to evaluate feasibility and potential impacts of the proposed project utilizes many available sources of regional hydrogeologic data, groundwater conditions, and environmental status. In addition to numerous reports by private consultants that are also cited in in the RDEIR, the following public sources of information and data were used to establish baseline conditions:
California Coastal Commission, California Department of Conservation, California Department of Water Resources (DWR), California Department of Fish and Game, California Department of Fish and Wildlife, California Division of Mines & Geology, California State Mining and Geology Board, California Geological Survey, California Resources Agency, Fort Ord Reuse Authority, Marina Coast Water District, Monterey County Planning Department, Monterey County Regional Water Agency, Monterey Peninsula Water Management District, Monterey Regional Water Pollution Control Agency, Monterey Bay Aquarium Research Institute, Monterey Bay National Marine Sanctuary, National Oceanographic AtmosphEIRc Administration (NOAA), National Research Council, National Marine FishEIRes Service, Pajaro Valley Water Management Agency,
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Seaside Groundwater Basin Watermaster, Regional Water Quality Control Board, State Water Resources Control Board, United States Environmental Protection Agency (EPA), and United States Geological Survey.
Geology and groundwater conditions along the coastal margin of the Salinas Valley Groundwater Basin, as well as in communities of Marina Coast, Fort Ord, Seaside, Sand City, and Monterey have been studied for many decades. The conceptual hydrogeology on which the Northern Marina Groundwater Model (NMGWM) is based is presented Section 2 of Appendix E2 to the RDEIR. The framework of the NMGWM is based on the regional Salinas Valley Groundwater Basin models with refinements based on local hydrogeologic data along the coastal margin and near the proposed site at the CEMEX facility. These data and the NMGWM include estimated extent of the Dune Sand Aquifer, extent and thickness of the Salinas Valley Aquitard, and extent of the 180-foot Aquifer. Six exploratory borings were drilled along the coastal margin near the CEMEX Facility to investigate hydrostratigraphy and make site-specific measurements of hydraulic properties. Testing at the borings included
water quality samples in 15 aquifer zone locations, grain-size analysis and calculations of hydraulic conductivity (K), laboratory testing of horizontal hydraulic conductivity (Kh) and vertical
hydraulic conductivity (Kv) on core samples, and geophysical logs
Detailed reporting on the CEMEX borings and testing is provided in Appendix C3 of both the DEIR and RDEIR.
A long-term pumping test of the test slant well at 2000 gpm began 22 April 2015. Water levels and electrical conductivity is recorded with transducers and data loggers in six monitoring wells and reports are available from the project web-site1. The CEMEX model was used to simulate the test slant well pumping and re-calibrated to the long-term data (Geoscience, 2016). The resulting
1 http://www.watersupplyproject.org/testwellmonitoring
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changes in aquifer parameter vales in the re-calibrated CEMEX model were incorporated in the updated NWGWM for the RDEIR (HydroFocus, 2016).
Revisions to the updated NMGWM included refinement of the model extent and properties of the Fort Ord - Salinas Valley Aquitard (FO-SVA), which was a key recommendation by the Lawrence Berkeley National Laboratory review of the NGWMM2015 (LBNL, 2016, included as Appendix E1 of RDEIR). The FO-SVA hydraulically separates the Dune Sand and 180-foot-equivalent (180-FTE). The FO-SVA was added south of the Salinas River in the NMGWM2016 and a transition zone was added where the FO-SVA thins toward the coast (HydroFocus, 2016). Note that as part of the review of the NMGWM2015, LBNL re-ran models using files provided by the CPUC, and compared results of their model results with those presented in Appendix E2 of the DEIR. LBNL reported that their model runs closely replicated the results for both the CMEX and Northern Marina Groundwater Model (NMGWM2015) that were presented in Appendix E2 of the Draft E2 of the DEIR.
The RDEIR shows 500 mg/l chloride threshold for the regional scale characterization of extent of sea water intrusion (SWI) as defined by the MCWRA (every two years). 500 mg/l chloride is the California secondary maximum contaminant level (MCL) recommended upper limit for consumer acceptance level for potable water. Development of new water supply with water greater than 500 mg/l would require blending or treatment. We agree that groundwater quality (salinity) is locally variable, but detailed characterization of groundwater quality and quantity in the Dune Sand Aquifer is not relevant to the evaluation of feasibility and potential impacts of the project. Moreover, both quality and quantity of groundwater in the Dune Sand varies temporally with rainfall, particularly at local occurrences of perched groundwater. Note however, that a recent geophysical survey along the Monterey Bay Coastline using electrical resistivity tomography (ERT) indicates that while the distribution of saltwater intrusion is variable and complex in portions of the 180-ft and 400-ft Aquifers, the saltwater intrusion is relatively ubiquitous and uniform within the Upper Alluvium including the Dune Sand Aquifer. The only exception appears to be a prominent area of shallow fresh water within the Fort Ord Dunes approximately 6.3 miles south of the CEMEX Plant that is attributed to recharge from water diverted from storm water ponds (Goebel et al, 2017).
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Comments on the model properties, design and calibration. Model layering, boundary conditions and properties were improved based on additional data and comments (including peer reviews). Calibration of the NMGWM2016 model is generally improved compared to the NMGWM2015. The model does not simulate unsaturated flow and does not represent perched groundwater. Shallow perched groundwater occurs locally in the Dune Sands including highland areas of Fort Ord. Groundwater elevation contour maps such as Hopkins Fig 6, that include elevations of perched groundwater in the landfill and Fort Ord areas are incorrect. The areas of perched groundwater are not hydraulically connected to the regional water table and should not be included in regional water table elevation contour maps. As documented in the RDEIR (Appendix E2), incorporating the influence of variable density on groundwater flow has negligible influence on model results. Comments that the superposition modeling is not appropriate. The MCWD letter includes numerous claims that the superposition modeling is not appropriate. The RDEIR explains the limitations of the modeling in general and specifically the superposition modeling.
Superposition modeling is a common method to evaluate impact of pumping (e.g. Arizona Department of Water Resources requires all stresses other than the proposed pumping to be removed from models to evaluate potential impact for permitting of proposed pumping wells).
Standard aquifer testing analysis is superposition modeling. The superposition modeling approach directly estimates the lowering of the groundwater
levels associated with proposed project pumping. It does not preclude prediction of changes in groundwater elevation associated with the
project. MCWD is correct that the model does not evaluate groundwater quality, but return flow
will be based on data (salinity of the pumped water), not modeling.
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Monitoring and Mitigation Measures My understanding is that MCWRA is planning a monitoring program. Mitigation would include greater portion of return water Comments on depletion of groundwater in the Dune Sand Aquifer and resulting decrease in recharge to 180-FTE Aquifer
If groundwater in the Dune Sand was a significant resource there would be wells in it. There are no irrigation wells in the Dune Sand because of the sporadic unreliable presence of water.
Recharge to the 180-FTE Aquifer from water in the Dune Sand clearly has not prevented SWI in the 180 FTE aquifer.
Lowering of water levels in the 180 FTE could enhance leakage into the 180-FTE from Dune Sand in areas where they are hydraulically connected, but separated by a semi-confining layer (leaky aquitard).
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REVIEW OF HGC COMMENTS (pgs 1-8, and comments #23-28, #30, #31, #32, #35, #36, #38, & #39) Comments and claims by Hopkins Groundwater Consultants (HGC) in his 29 March 2017 letter are provided followed by my opinion and discussion in blue italics. Pages 1-8 HGC claims that the RDEIR and associated updated North Marina Groundwater Model (NMGWM2016) “mischaracterizes the project and the complex hydrogeological conditions in the project area by incorrectly suggesting, without any supporting evidence in many cases, that:”
1. “The intake system will induce flow vertically through the ocean floor… “ This is not mischaracterization. It is true the a large portion of the source water would be drawn vertically through the ocean floor.
2. “The shallow aquifers along the coastline around the CMEX site are fully intruded by seawater … “
The RDEIR makes no such claim.
3. “The groundwater gradient (flow) in all aquifer zones produced by the project is onshore (inland or away from the coast) in the entire area …”
The RDEIR makes no such claim. In fact Figures 5.6 and 5.7 of Appendix E2 (HydroFocus, 2016) present model results that show local flow directions from inland toward the proposed project wells.
4. “Historical studies are sufficiently complete and comprehensive in nature to document conditions in the vicinity of the project…”
The RDEIR makes no such claim. In fact the updates to the NMGWM presented in the RDEIR utilize newly acquired data from the slant well testing program. However, sufficient information exists to provide the framework for a hydrogeologic conceptual model on which the numerical models are based.
5. “The limited exploration and testing to date sufficiently validates assumptions in the DEIR/EIS’s groundwater models…”
The RDEIR makes no such claim. Many of the assumptions made for the groundwater modeling analyses have nothing to do with exploration and testing, but on physical principles of
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groundwater flow. Moreover, the updates to the groundwater modeling presented in the RDEIR do utilize results of additional testing and data compilation.
6. “The DEIR/EIS’s superposition model is reliable and demonstrates that the project’s potential impacts on groundwater levels and groundwater quality in the Marina Subarea will be less than significant.”
Estimates of the project’s impacts on groundwater levels based on the superposition model are reasonably reliable. The superposition model does not simulate changes in groundwater quality.
7. “Mitigation of the project’s impacts can be accomplished through multiple methods and means.”
This comment is vague. Mitigation measures depend on specific potential project impacts. HGC claims the calibrated NGWM2016 model was abandoned and replaced with the inferior superposition model. Superposition modeling is a common method to evaluate impact of pumping. For example, e.g. Arizona Department of Water Resources requires all stresses other than the proposed pumping to be removed from models to evaluate potential impact for permitting of proposed pumping wells. Type-curve analysis of aquifer testing is superposition modeling. I agree that the superposition modeling has limitations. For example, it can’t be used directly for evaluation of capture zone of the project wells. HydroFocus superimposed the regional hydrologic gradient on the superposition model results to evaluate capture zones. Note also that GeoHydros (discussed below) ran project pumping simulations with the NGWM2016 calibrated model and obtained very similar results for drawdown of groundwater to HydroFocus with the simplified superposition modeling approach. HGC claims the perched groundwater in portions of the Dune Sand Aquifer and -2-Foot-Aquifer beneath the County Landfill, which are not addressed by the NGWM2016, are important for evaluating potential impacts of project pumping. I disagree. The proposed project pumping cannot impact the local occurrences of perched groundwater in the Dune Sands because they are not hydraulically connected to the regional water table. Moreover, the -2-foot Aquifer, which occurs beneath the County Landfill is underlain by the Salinas Aquiclude, which is s competent and widespread barrier that separates the shallow perched zones from water supply aquifers including the 180-foot, 400-foot aquifers (California Regional Water Quality Control Board, 2006).
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HGC claims the DEIR/EIS fails to evaluate the project impacts on a perched groundwater in portions of the Dune Sand Aquifer, which are not addressed by the NGWM2016, are important for evaluating potential impacts of project pumping. I disagree. The proposed project pumping cannot impact the local occurrences of perched groundwater in the Dune Sands because they are not hydraulically connected to the regional water table. HGC claims the DEIR/EIS incorrectly estimates capture zones of the project pumping. This is incorrect. HydroFocus superimposed the regional hydrologic gradient on the superposition model results to evaluate capture zones. HGC claims that a dual density model should be used evaluate the proposed project pumping and water quality changes. Presumably HGC means variable density not dual density. But accounting for the influence of density on groundwater flow due to variation in salinity is not important to evaluate the proposed impacts of project pumping because the influence of density variation is negligible compared to slant well pumping and uncertainties in hydraulic conductivity. This is discussed and demonstrated by (HydroFocus, 2016, Appendix E2 to the RDEIR). Seawater is only 2.5% more dense than freshwater. HGC Comment 23 HGC claims the slant well screens are not beyond the jurisdictional boundaries of the County. Apparently this pertains to the relationship between the location of the wells screens and the coastline. Presumably it also depends on the location of the source water pumped by the wells. I defer to legal counsel on this issue. However, please note that the freshwater/seawater interface is not a distinct boundary beneath the coastline and in many settings, the fresh groundwater/sea water transition beneath the ocean floor is well beyond the coastline. The distinction between fresh groundwater and sea water is based on salinity, not location. HGC claims the updated model (NMGWM2016) presented in the RDEIR relies on the CEMEX Model Update (Geoscience, 2016), which HGC says makes unsupported assumptions.
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The CEMEX model was used to simulated the test slant well pumping and re-calibrated to the long-term data (Geoscience, 2016). The resulting changes in aquifer parameter vales in the re-calibrated CEMEX model were incorporated in the updated NWGWM2016 as presented in the RDEIR (HydroFocus, 2016). The NWGWM2016 incorporates results of updates to the CEMEX model, but does not rely on the CEMEX model. Not possible to address the “unsupported assumptions” claimed by HGC because HGC does not describe them. HGC Comment 24 HGC claims that baseline water levels were not established prior to the testing of the slant well. HGC also claims there was no information regarding tidal, seasonal, or climatic variations, and that it was unclear what was considered as pre-pumping conditions.
I disagree. Baseline monitoring of water levels and water quality were recorded for seven weeks prior to the initiation of the test well pumping. Moreover, monitoring was continued when the test well pumping stopped for regulatory review or maintenance, including approximately four months in 2015 and several weeks in 2016. The hydrographs presenting monitoring data recorded for prior and during test well pumping program clearly illustrate baseline conditions and tidal influence. Rainfall data are also included to facilitate assessment of influence on groundwater levels.
Monitoring reports are prepared on a weekly basis for the California Coastal Commission and monthly monitoring reports are prepared for Cal Am. The monitoring reports are available from the project web site: https://www.watersupplyproject.org/test-well
HGC expresses concern that project impact in terms of drawdown of groundwater levels assessed during pumping in drought conditions when groundwater levels were low are not representative of typical conditions when groundwater levels are higher. Higher water level conditions after the drought increases transmissivity, which results in less drawdown impact of the test well pumping in the unconfined surficial aquifers. Assessing influence of test well pumping on groundwater levels for drought conditions provides a conservative assessment of project impact.
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HGC claims the degree of uncertainty in the groundwater modeling is intolerable. I disagree. The degree of uncertainty is typical and acceptable. Results of sensitivity analyses are presented to illustrate the uncertainty. The modeling is intended to evaluate the potential impacts of the proposed project pumping, not other potential future changes in pumping. HGC Comment 25 In Comment 25, HGC again claims the degree of uncertainty in the groundwater modeling is intolerable. HGC also states the superposition modeling used to evaluate potential drawdown of groundwater levels by the proposed project pumping cannot be used to evaluate potential impacts to groundwater quality or water budget (different sources of water).
I disagree that the degree of uncertainty in the groundwater modeling is intolerable. The degree of uncertainty is typical and acceptable. Results of sensitivity analyses are presented to illustrate the uncertainty.
The superposition model was not used to evaluate potential impacts to groundwater quality. Nor was it used to estimate portions of sources of water pumped by the proposed project. I agree that the model does not simulate changes to local occurrences of perched groundwater in the dune sands. This is nothing to do with superposition. MODFLOW only simulates saturated flow conditions, and unsaturated conditions exist below perched groundwater. Perched groundwater is not hydraulically connected to the aquifers that would be pumped by the project wells, and therefore cannot be impacted by the project pumping. HGC also again claims the assessment of potential impacts of the project pumping are based on inadequately defined baseline conditions and that the modeling is fatally flawed.
I disagree.
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HGC Comment 26 In Comment 26, HGC again claims baseline conditions are not investigated, the modeling is flawed, does not utilize best available information, and that potential interference with groundwater recharge is not evaluated. I disagree with all these claims. Note also that the model updates use most current information on groundwater conditions including ongoing monitoring data for the test slant well pumping. HGC Comment 27 In Comment 27, HGC claims the that Figure 4.4-13 of the RDEIR is simplistic and somehow erroneous? Figure 4.4.-13 shows the modeled “worst-case” drop in groundwater levels (drawdown) in the 180-FTE aquifer caused by continuous project pumping for 63 years with no delivery of return water to replenish the inland aquifers. The superposition model provides the estimated impact on groundwater levels only of the project pumping, which is the objective of the analysis. Other unknown potential changes in pumping are not included. Based on the analysis, which includes the groundwater modeling, the project pumping would have less than significant impact on water quality, depletion of storage, and on groundwater dependent ecosystems. The analysis for the RDEIR also includes assessment of influence of projected rise in sea level, because this is expected to occur. Higher sea level will result in a slightly greater portion of sea water flowing to the slant wells and thus a decrease the portion of inland groundwater. Figures 4.4-14 – 16 of the RDEIR show the range of the extent of greater than 1-foot-drawdown in the Dune Sand, 180-FTE, and 400-ft Aquifers for current sea level and with sea level rise after 63 years and with a return water range of 0 to 12%. In Comment 27, HGC again claims baseline conditions are not investigated, the modeling is flawed, and does not utilize best available information. I disagree.
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HGC Comment 28 In Comment 28, HGC comments that the superposition model cannot quantify the amount of seawater and fresh groundwater that the project wells would pump. Although the superposition is not used to quantify portions of seawater and groundwater from inland aquifers pumped by the proposed wells, it could be. In Comment 28, HGC again claims baseline conditions are not investigated, the modeling is flawed, and does not utilize best available information. HGC also claims the hydraulic conductivity values assigned to the superposition model are not reliable. I disagree. In Comment 28, HGC claims that the proposed slant wells would be within the jurisdictional boundary of County Ordinance 3709. I defer to legal counsel on this issue. However, my understanding is this is correct and is the reason that the portion of fresh groundwater pumped by the project will be returned to the groundwater basin. My understanding is the plan to return water from the project to the groundwater basin is conditionally acceptable to the State Water Board (2013, included as Appendix B2 of RDEIR). HGC Comment 30 In Comment 30, HGC refers to additional modeling of the project pumping conducted by GeoHydros using the re-calibrated NMGWM2016, and points out that the model indicates that the initial portion of groundwater pumped by the project wells would be 30%. The same modeling indicates that the total groundwater portion would decrease to 11% in one year and remains at approximately 10% from 2 to 32 years. This is generally consistent with previous groundwater modeling with the NMGWM2015 reported in the DEIR and is within the range of assumed replenishment obligations addressed with the NGWM2016 modeling presented in the RDEIR (0 to 12%). Note that a greater groundwater replenishment obligation lessens potential inland impacts of the project pumping.
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HGC also claims that the project would reduce groundwater storage. I agree. The modeled drawdown of the water table, which is addressed in the RDEIR, shows this HGC claims that the amount of return water needs to be indicated and analyzed. The RDEIR evaluates potential project impacts for a range of return water (0, 3, 6, and 12%) based on groundwater replenishment obligations estimated by previous modeling. The updated modeling for the RDEIR does not re-evaluate the portions of ocean water and inland groundwater water pumped by the project wells. However, as discussed above, the additional modeling presented with comments by GeoHydros indicates that the groundwater portion would be approximately 10% (Ocean Water 90%) after approximately 2 years of pumping. The portion of fresh groundwater would be less than 10% because most of groundwater in the coastal margin aquifers has been impacted by sea water intrusion. More importantly, based on a water purchase agreement between MCWD, MCWRA and Cal Am (2010), the determination of the quantity of return water from the project for the groundwater replenishment obligation will be calculated based on the salinity of the water pumped by the project wells using the following formula to calculate the portion of Ocean Water and Inland Fresh Water that was provided in Appendix E2 to the DEIR:
X = (FS-IS)/(OWS-IS) Where, X is Proportion of Ocean Water in Intake Water, (1-X) is Proportion of Fresh Water, OWS is Ocean Water Salinity = 33,500 mg/L TDS FS is Feedwater Salinity, and IS is Inland Water Salinity (Fresh Water) = 440 mg/L TDS, which is based on inland Salinas Basin groundwater that is not impacted by sea water intrusion.
For example, Feedwater with salinity of 32,000 mg/L consists of 95.5% Ocean Water and 4.5% Inland Fresh Groundwater. Based on the NMGWM pumping simulations presented in the DEIR, over the long term, the average intake water consists of 94.5% ocean water, and 5.5% inland fresh groundwater, which require replenishment of 1,458 AFY (1.3 mgd) for the proposed project pumping of 24 mgd. The RDEIR states that a mathematical formula will be used to calculate the quantity of water to be retuned the groundwater basin each year (pg 4.4-49), but does not seem to provide the formula.
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Note that based on the salinity of water pumped by the test slant well, the calculated portion of ocean water using the above formula was initially approximately 75%, but approached the estimated range of 93 to 96% based on NMGWM2015 modeling, after a few months of pumping. However, the last several months the salinity has been generally decreasing and based on salinity reported for a sample collected 21 June 2017 (Geoscience, 2017), the Ocean Water Portion has decreased to 84%. Presumably the change is due to dilution of salinity in the shallow coastal aquifers associated with recharge of fresh water associated with the abundant rainfall this year. In Comment 30, HGC comments that groundwater that is degraded by seawater intrusion is useable because it can be treated. I agree that brackish or saline water can be treated to potable water standards. Indeed, this is the plan of the proposed project. HGC is correct that the State’s TDS threshold is 3,000 mg/L for designation as potentially suitable for municipal or domestic water supply.2 However, the State Water Resources Board secondary maximum contaminant levels for TDS in drinking water are 500 mg/L TDS (recommended) and 1000 mg/L TDS (upper limit)3. In Comment 30, HGC claims the modeling needs to consider cumulative drawdown. I disagree. The purpose of the analysis for EIR is to assess potential impacts of the project pumping, not unknown other possible future pumping. I agree that drawdown of groundwater levels in the range of 1 to 5 feet is less than significant impact to existing production wells. Typical seasonal variations of groundwater levels are greater. HGC Comment 31 In Comment 31, HGC again claims the modeling needs to consider cumulative drawdown. I disagree. The purpose of the analysis for the EIR is to assess potential impacts of the project pumping, not unknown other possible future pumping.
2 https://www.waterboards.ca.gov/board_decisions/adopted_orders/resolutions/2006/rs2006_0008_rev_rs88_63.pdf 3 http://www.waterboards.ca.gov/gama/docs/coc_salinity.pdf.
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In Comment 31, HGC states that the reported findings regarding potential project impacts to Tembladero and Elkhorn Sloughs are inconsistent in Sections 4 and 5 of RDEIR. I disagree. As explained by the excerpts from the RDEIR included in HGC’s Comment 31, the alternative project, which would be pumping from slant wells at Potrero Road, would have greater potential impact on Elkhorn Slough because of the proximity of the slant wells to the Slough. HGC Comment 32 In Comment 32, HGC states again that the reported findings regarding potential project impacts to Tembladero and Elkhorn Sloughs are inconsistent in Sections 4 and 5 of RDEIR. I disagree. As explained above for HGC Comment 31. In Comment 32, HGC states that the evaluation of the slant well pumping with surface water at the CEMEX facility is inadequate, and the therefore the modeling presented in the RDEIR is subject to intolerable uncertainty. I disagree. Moreover, the CEMEX dredge pond is hydraulically connected to the ocean and is simply a window into the water table beneath the sand. The Pacific Ocean is the source of water to the CEMEX dredge pond. I agree that the potential impact of the project pumping on recharge to the Dune Sand Aquifer and sand mining operations is less than significant. HGC Comment 35 In Comment 35, HGC states again that the evaluation of potential impacts to groundwater resources reported in the RDEIR and the proposed measure 4.4-3 for groundwater monitoring are inadequate. I disagree. Moreover, my understanding is that MCWRA will oversee developing a groundwater monitoring program to evaluate if the project pumping impacts the performance of local production wells. HGC Comment 36 In Comment 36, HGC expresses concern that the project could result in fresh and brackish groundwater becoming “hypersaline”, and that the RDEIR fails to address this possibility. Also, HGC states again that the modeling must be updated to address project impacts to water quality.
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It is not possible that project would cause groundwater to become hypersaline as HGC claims. Hypersaline means salinity greater than ocean water. Local temporal and spatial variations in salinity of groundwater along the coastal margin where there are no production wells are not relevant to evaluation of potential impact of the project pumping. Model calculations (particle tracking presented by Figure 4.4-17 of the RDEIR) show that the project has insignificant influence on the inland extent of sea water intrusion. The determination of the quantity of return water from the project for the groundwater replenishment obligation will be calculated based on the salinity of the water pumped by the project well. My understanding is the plan to return fresh water from the project to the groundwater basin is conditionally acceptable to the State Water Board (2013, included as Appendix B2 of RDEIR). HGC Comment 38 In Comment 38, HGC expresses concern that additional evaluation is needed of potential influence of the proposed project pumping on contamination beneath the Fort Ord remediation site using a “revised and calibrated or a new dual density model”. I disagree. The RDEIR adequately address potential impact of the proposed project pumping on contaminated groundwater including the plumes at Fort Ord. The main plume of contaminated groundwater is called the Operable Unit Carbon Tetrachloride Plume (OUCTP), although it also includes trichloroethene (TCE) (Mactec, 2006). The larger extent of contamination is within the A-Aquifer, which is within recent dune sands. The A-Aquifer is separated from the 180-FTE Aquifer by the regional Fort Ord – Salinas Valley Aquitard (FO-SVA). As stated by the RDEIR the A-Aquifer is a shallow inland aquifer above the 180-Foot Aquifer and is not known to be hydraulically connected to the Dune Sand Aquifer at the proposed slant well locations. Stability in groundwater elevations in the A-Aquifer (Plate 12, Mactec, 2006) support that this aquifer is hydraulically isolated from pumping from irrigation wells in the underlying 180-foot and 400-foot aquifers to the east in Salinas Valley (pg 12, Mactec, 2006). Moreover, hydrographs for monitoring wells in the upper and lower portions of the 180-ft aquifer beneath Fort Ord show seasonal variation in groundwater levels of greater than 5 and 10 feet, respectively
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(Plates 13 and 14, Mactec, 2006), which is likely due to variable influence of pumping from irrigation wells. The potential influence of the project pumping at Fort Ord in the 180-FT aquifer would be much less. Moreover, accounting for variable density based on salinity (not “dual density”) would have negligible influence on the model calculations in the vicinity of the Fort Ord plumes. HGC Comment 39 In Comment 39, HGC expresses concern that the evaluation presented in the RDEIR only addresses potential impacts of the project pumping. Indeed, the intent is to evaluate potential impact of the proposed project pumping. There is no basis to simulate future potential changes in pumping associated with unknown other projects. Sensitivity analyses were conducted that provide a range of estimated project impacts, and the potential impacts with compensation for projected sea level rise.
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REVIEW OF GEOHYDROS COMMENTS
Claims and comments by GeoHydros (GH) in their 27 March 2017 letter are followed by my opinion and discussion in blue italics. Section 2. NMGWM GH (page 1) says updates to the NMGWM2016 include “structural changes that favored the conceptualized flow from the Pacific Ocean into the aquifers.” GH’s statement implies that the updates were intended to result in a larger portion of ocean water flow to the model slant wells. But the changes by HydroFocus to the offshore boundary conditions and initial conditions were improvements to the model. These changes are listed below:
Changed Layer 1 (ocean specified head) to represent actual thickness. 2015 used uniform 1-ft thickness.
Activated all cells in ocean with specified heads. In the NMGWM2015 version, the offshore cells were inactive resulting in offshore no-flow boundaries, which inappropriately lessened connection to the sea—particularly for steady-state model runs.
Added equivalent fresh-water heads used for offshore boundary conditions. The water levels represent hydraulic potential, or hydraulic head, and are corrected for density differences between the high saline, denser ocean water relative to the less saline, less dense inland groundwater. These corrected water levels are referred to as “equivalent freshwater heads.”
GH (page 2): “The model boundaries are arbitrary and do not represent natural hydrologic divides therefore the model simulates flow across the external boundaries that cannot be verified from data.” Presumably GH means the model extent is arbitrary. The model extent is not arbitrary, but is based on the geography and hydrogeology of the project vicinity and utilizes information from more regional models. The NMGWM covers nearly 150 square miles; the boundary conditions are acceptably far-removed from the location of proposed project pumping. The model would need to cover the entire Salinas Valley and portions of adjacent highlands for the inland boundaries to represent physical hydrologic divides. The extent of the model domain is appropriate for the purposes of the analysis and consistent with standard practice. GH (page 2): GH criticizes the use of equivalent freshwater heads for the ocean boundary conditions, but no use of equivalent freshwater heads for inland groundwater with elevated salinity
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due to saltwater intrusion. They claim that a dual-density model such as SEAWAT or FEFLOW would be the appropriate way to simulate saltwater intrusion. The use of equivalent freshwater heads for ocean boundary conditions is common practice and reasonable. We agree that a variable density (not dual-density) model such as SEAWAT could be used to simulate variable salinity distribution and potential change in salinity distribution due to the project pumping. However, the objective of the modeling was not to specifically simulate sea water intrusion and salinity distribution. Moreover, as reported in the RDEIR (pg 26 of Appendix E2), model simulations were conducted using SEAWAT to evaluate the error associated with neglecting to account variable density in the NMGWM2016. The results demonstrated that accounting for the influence of density on groundwater flow due to variation in salinity is not important to evaluate the proposed impacts of project pumping because the influence of density variation is negligible compared to slant well pumping and uncertainties in hydraulic conductivity. This is discussed and demonstrated by (HydroFocus, 2016, Appendix E2 to the RDEIR). Seawater is only 2.5% more dense than freshwater.
GH (page 2-3): GH comments that interconnectivity between the regional Salinas Valley Model (SVIGSM) and the NMGWM model are problematic. I agree. But, the regional Salinas Basin model and NMGWM model are not intended to be “interconnected”. They are of different scales and detail. As discussed in the RDEIR (Appendix E2, HydroFocus, 2016), the differences between the models influence the large calibration errors. Note however, that much of the calibration error is a consequence of inaccurate initial heads particularly in the Dune Sand aquifer. The 180-FT aquifer is the uppermost aquifer system in which horizontal groundwater is simulated by SVIGSM. SVIGSM was not designed to simulate horizontal groundwater flow in the shallow Perched A or Dune Sand Aquifer. So, it is not surprising that the boundary conditions and initial heads derived from SVIGSM for the Dune Sand Aquifers were not accurate. It seems that GeoHydros recognizes that the inaccurate initial heads based on the SVIGSM have little influence on the equilibrium (steady-state) simulations of the proposed project pumping, which is why they used the calibrated version of the NMGWM2016 to independently run simulations of the proposed project pumping instead of the simplified version used for the superposition modeling.
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Another key factor regarding the “poor calibration” is that the groundwater within the Dune Sand locally is perched—hydraulically not connected to the regional water table. MODLOW does not simulate unsaturated flow of groundwater. GH (page 3): GH Figures 8 and 9 show contours of groundwater levels for their 32 transient runs of the calibrated version of NMGWM2016 for the 400-ft and 900-ft aquifers. GH claims the model overestimates the inland directed hydraulic gradient in these aquifers. Apparently GH Figures 8 and 9 are for model runs without the proposed project pumping. Seems to me the differences between the initial time step and result at 32 years is simply a consequence of equilibration groundwater levels between the assigned initial heads and the solved heads, which are mainly controlled by the boundary conditions. Inaccuracy of initial heads assigned to the model for starting conditions has no relevance to the reliability of steady-state simulations of the project pumping. Evidence of extensive sea water intrusion into the 400-ft aquifer indicates that inland from the ocean has and is occurring. Moreover, the low groundwater elevation in the 400-ft aquifer near the northeast extent of the model are based on measured water levels. I agree that the model results depicted for the 900-ft aquifer by GH Figure 9 may overestimate inland flow of groundwater from the ocean, but this would have little if any influence on the reliability of the model simulations of the project pumping in the shallow aquifers. GH (page 3-4): GH discusses the model calibration and points out the model fails the stated calibration test in the Dune Sand Aquifer. Some of the groundwater elevations for the A-Aquifer (Dune Sand) are for occurrences of perched groundwater that are not hydraulically connected to the regional water table and should not be included in the MODFLOW model, which cannot simulate flow of perched groundwater. This does not influence the reliability of the model simulations of the proposed project pumping. In most respects, the NMGWM2016 model is improved compare to the NMGWM2015, particularly with respect to aquifer properties and geometry near the project. GH (page 4): GH claims the sensitivity analyses conducted by HydroFocus on the NMGWM2016
(Figures 6.1 & 6.2, Appendix E2) show a five-fold increase in horizontal hydraulic conductivity (Kh) coupled with five-fold decrease in vertical hydraulic conductivity (Kv) nearly doubles the size of the modeled cone of depression in the Dune Sand Aquifer.
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GH is incorrect. Hydrofocus Figure 6.2 shows that the sensitivity with maximum anisotropy (five-fold increase in Kh coupled with five-fold decrease in Kv) decreases the modeled extent of groundwater drawdown due to the proposed pumping. But, minimum anisotropy (five-fold decrease in Kh coupled with five-fold increase in Kv) increases the modeled extent of groundwater drawdown. I agree that improvement of model calibration is possible, but the range of potential drawdown based on the sensitivity analyses is considered in the evaluation of potential impacts of project pumping presented in the RDEIR. Section 3. Superposition Model GH (page 5) discuss the simplified superposition modeling approach that HydroFocus used to evaluate potential drawdown of groundwater levels due to the proposed project pumping. GH states that “though superposition modeling is a valid technique, it isn’t necessary or appropriate for these evaluations…”. I agree that the simplified superposition modeling approach isn’t necessary. But it is appropriate for evaluating potential impacts of the proposed project pumping. GH claims that “superposition modeling precludes evaluation of impacts to the water budget associated with the proposed pumping…”, and that “superposition modeling precludes prediction of measurable changes associated with the proposed pumping (i.e. predicted groundwater elevations and gradients)”. I disagree. Water budget information from superposition modeling can be used to estimate portions of source water associated with the proposed project pumping. It also can be used to predict changes in groundwater elevations and hydraulic gradient. GH obtained the model files and independently ran simulations of the proposed project pumping with the calibrated (unsimplified) version of NMGWM2016. GH claims that comparison of the results of the model runs they did with the calibrated (unsimplified) version of NMGWM2016 show that the superposition model approach used by HydroFocus underestimates the extent of groundwater drawdown by the proposed project pumping (GH Figures 10-13). GH Figures 10-13, which are included as Attachment 1 to this memo, provide a comparison of the results of the two modeling approaches. The modeled drawdown calculated using the two
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different modeling approaches are nearly identical. Moreover, the difference between the extent of drawdown calculated using the two approaches are well within the uncertainty considered in the analysis and findings by the RDEIR based on the sensitivity analyses on the model results. Section 4. Evaluation of Potential Impacts GH (page 5-6) states that “the calibration and boundary condition problems … render predictions dEIRved from the NMGWM unreliable particularly with respect to the Dune Sand Aquifer…” I disagree. In fact, as discussed in the previous comment above, the additional modeling runs conducted by GH support that the results of the simplified superposition model presented in the RDEIR are reasonable, and that the superposition modeling approach is valid. GH (page 7-8) report and discuss water budget calculations of source water to the slant wells based on their model simulations of the project pumping. The model runs by GH and their presentation of source water calculations are helpful. The model results by GH indicate that source water is approximately 30% inland groundwater after one month of pumping, but groundwater contribution decreases to 11% in one year and remains at approximately 10% from 2 to 32 years. The portion of fresh groundwater would be less than 10% because most of groundwater in the coastal margin aquifers has been impacted by sea water intrusion The results of the water budget calculations based on the model runs by GH are generally consistent with previous groundwater modeling with the NMGWM2015 reported in the DEIR and are within the range of assumed replenishment obligations addressed with the NGWM2016 modeling presented in the RDEIR (0 to 12%). Note that a greater groundwater replenishment obligation lessens potential inland impacts of the project pumping.
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Section 5. Conclusions GH (page 8) concludes that the NMGWM2016 is poorly calibrated in the Dune Sand Aquifer, the quality of model calibration of the NMGWM2016 is not as good as for the NMGWM2015, and the reliability of predicted impact of the project pumping is undermined by the poor calibration. The “poor calibration” is a consequence of including data for areas of perched groundwater in the shallow aquifers (Dune Sand and A-Aquifer). Local occurrences of perched groundwater are isolated hydraulically from the regional water table by intervening unsaturated intervals and MODFLOW does not simulate the flow of groundwater for unsaturated conditions. I agree that data are limited for calibration of model properties for the shallow aquifer (Dune Sand Aquifer), however, the hydraulic conductivity properties assigned for the Dune Sand are reasonable, and the variation in hydraulic conductivity for the sensitivity analyses provides a conservative assessment of potential impact of the proposed project pumping. GH (page 9) states that the model results indicate that 2.8% or 756 acre-feet per year is predicted to come from the 400-ft and 900-ft aquifers, which will contribute to overdraft in those aquifers. GH Table 3 indicates 1.9% and 0.9% from the 400-ft and 900-ft aquifers, respectively. The potential impacts to the 400-ft and 900-ft aquifers of the proposed project pumping are evaluated by the RDEIR and found to be less than significant. GH (page 10) states that “The sensitivity analyses performed by HydroFocus with respect to hydraulic conductivity indicate that the predicted impacts could be substantially understated, which demonstrates the importance of achieving better calibration.” This statement is misleading. The sensitivity analyses show a range of potential impacts of the project. The range of potential impacts is considered by the RDEIR. The level of uncertainty is acceptable for the purpose of evaluating the potential project impacts as presented by the RDEIR. GH (page 10) states that “Based on the findings presented in this report, we believe that the Draft EIR/EIS’s conclusions regarding the MPWSP’s groundwater impacts are not scientifically supportable and that they conflict with available information.” I disagree. The model findings are scientifically supportable are consistent with abundant information. The model approximates subsurface conditions and is not intended replicate complex heterogeneity of subsurface properties. The model is a reasonable screening tool designed to evaluate potential project impacts. The other bullet points by GH in their conclusion section are addressed above.
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REVIEW OF COMMENTS BY EKI Nearly all the comments and concerns by EKI (29 March 2017) are essentially the same as by Hopkins and GeoHydros, which are addressed above. EKI states that “the Project will preclude MCWD from utilizing the Dune Sand Aquifer for storage and/or augmentation of groundwater supplies through surface water recharge at Armstrong Ranch”, and that the RDEIR needs to address this. I disagree that the project would preclude the MCWD from utilizing the Dune Sand Aquifer for storage and/or augmentation of groundwater supply by recharge at Armstrong Ranch. Moreover, the RDEIR does address potential impacts of project pumping including estimated drawdown of groundwater levels in the vicinity including Armstrong Ranch. Armstrong Ranch is thousands of feet beyond the estimated extent of groundwater capture by the proposed project pumping. The capture zone envelopes for the proposed project pumping of 24.1 mgd were calculated by HydroFocus for the Dune Sand and 180-FTE Aquifers (Figure 5.6 Appendix E2, RDEIR) for a range of hydraulic gradients. These capture zones are also shown on EKI Figures 11 and 12. Figure 137 of Appendix E2 from the DEIR, which is included as Attachment 2 to this memo, also shows the capture zone in the 180-FTE Aquifer associated with the project pumping, based on the NMGWM2015 for the proposed pumping of 24.1 mgd. Figure 137 (see Attachment 2 to this memo), also shows groundwater flow pathlines both with and without the project pumping. The pathlines on the attached figure help to show that with the project pumping would reverse the groundwater flow direction inland of the capture zone, so groundwater would flow towards the coast instead of inland. As is recognized and addressed by the RDIER, the proposed project pumping may increase salinity in the Dune Sand and 180-FTE Aquifers within the extent of hydraulic capture by the project wells. However, further inland, beyond the capture zone in locations such as Armstrong Ranch, the proposed project pumping should result in a long-term decrease in salinity the Dune Sand and 180-FTE Aquifers due the reversal of groundwater flow direction (flow toward the coast instead of away from the coast). Note, however, that any change in flow direction and water quality, due the project pumping, that could occur thousands of feet away from the extent of hydraulic capture would be minor and take many decades if not centuries. The model simulations of the proposed project pumping show that the potential extent of 1-foot drawdown of groundwater levels in the Dune Sand and 180-FTE Aquifers (Figures 4.4-14 and 4.4-15, RDEIR; Figures 9 and 10, EKI) reaches the vicinity of Armstrong Ranch. However, these
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small changes in groundwater elevation would not influence water quality or feasibility of enhanced recharge projects. Moreover, seasonal variation in groundwater elevation and hydraulic gradients due to variation in pumping and rainfall are much more significant, as discussed above in response to HGC Comment 38. Note also, that the Fort Ord-Salinas Valley Aquitard (FO-SVA), which hydraulically separates the Dune Sand and 180-foot equivalent (180-FTE) aquifers from greater than about 2 km east of the proposed MPWSP project site, limits recharge benefit from Dune Sand to 180-FTE Aquifer at Armstrong Ranch.
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REVIEW OF COMMENTS ON BEHALF OF CALIFORNIA UNIONS FOR RELIABLE ENERGY’S On behalf of California Unions for Reliable Energy (CURE) Linda Sobczynski with the law firm of Adams Broadwell Joseph & Cardozo submitted a letter dated 28 March 2017 (the CURE letter) to the CPUC and MBNMS with comments on the DEIR/EIS for the proposed MPWSP. I was asked to specifically review pages 38-41 of the CURE concerning the vertical infiltration rates to the source wells. Page 38 of the CURE letter states: “The DEIR/EIS fails to adequately analyze and mitigate potential significant impacts related to marine resources, particularly as those impacts are caused by the subsurface slant well technology.” More specifically, the letter claims that factors influencing vertical infiltration rates are not adequately analyzed including:
location of the submersible pump in the slant wells; sediment profile for the existing 19o slant wells and proposed 14o slant wells; packers in the slant wells; and clogging in the seabed.
I disagree that the RDIER fails to adequately analyze the vertical infiltration rate of ocean water into the sea floor that would be induced by the pumping from proposed slant wells. Section 4.5.5.2 (pages 4.5-51 to 53) of the RDEIR presents analysis of the vertical infiltration rate of water into the sea floor, and potential resulting impingement of marine organisms and organic material on the sea floor. The basis for the calculated vertical infiltration rate of ocean water into the seafloor is provided on page 4.5-52 of the RDIER. The calculation assumes that infiltration of ocean water would occur within a 1,000,000 sq ft. area of the seafloor: 2000 ft long along the coast, by 500 ft long perpendicular to the coast (offshore distance). If all 24.1 mgd (3,221,925 ft3/d) flows into the seafloor within this area, the average infiltration velocity of ocean water into the sea floor would be 3.22 ft/d, which equates to velocity of 0.011 mm/sec. As discussed in the RDIER, this calculated ocean water velocity into the seafloor is much lower than swimming speeds of marine organisms, and much lower than currents associated with waves and thus potential impingement of organisms and organic material on the sea floor due to the proposed project pumping is less than significant. I suggest that the infiltration velocity calculations should also include effective porosity of the sea floor sediment. Because water only flows through the connected void space (effective porosity) within the sediment, the velocity of water flowing within the sediment is faster. The lower the
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effective porosity, the higher the velocity. Assuming an effective porosity of 0.25 (25 percent) for the sea floor sediment, the velocity in the sediment would be four times higher: (0.011mm/sec divided by 0.25 = 0.0455 mm/sec). However, this more conservative velocity is still much lower than swimming speeds of marine organisms, and much lower than currents associated with waves and thus potential impingement of organisms and organic material on the sea floor due to the proposed project pumping is less than significant. Moreover, the calculated velocity of ocean water infiltration into the sea floor is conservative because not all the water pumped by the project wells would infiltrate through the assumed 2000 by 500 ft area of seafloor. A portion of the source water would come from inland groundwater and the area of seafloor through which ocean water would infiltrate would be larger than 2000 by 500 ft. I disagree that the location of the submersible pump is an important factor in the vertical infiltration velocity of ocean water through the sea floor. The location of the pump within the well will have little influence on the flow profile and negligible influence on vertical infiltration rate of ocean water into the sea floor. Note the that the depth of the slant wells where they would approach the coastline would be a couple hundred feet, and consequently the ocean water drawn into the slant wells would come from a large area. The detailed stratigraphy (sediment profile) for the existing test slant well, which is based on the boring log is depicted Figure 4c in Appendix E2 of the DEIR (ESA, 2015). The sediment profile for the proposed shallower angle slant wells (14 degrees instead of 19 degrees) will be similar and can be estimated from the stratigraphy shown by Figure 4c in Appendix E2 of the DEIR (ESA, 2015). Moreover, the hydrostratigraphy is approximated by the NMGWM2016, which includes updates based on specific information from borings logs in the project site vicinity. The distribution of inflow to the slant wells may influence salinity, but will have negligible influence on vertical infiltration rate of ocean water into the sea floor because of the large distance between the well screens and the sea floor and anisotropy of hydraulic conductivity within the sediments (Kh > Kv). I am not aware of any packers in the test slant well, or plans for packers in the proposed slant wells. Packers, which could be used to focus flow from portions of the well, could influence salinity, but would have negligible influence on vertical infiltration rate of ocean water into the sea floor for the same reasons discussed above. As discussed above and presented in the Section 4.5.5.2 of the RDEIR, the vertical velocity of ocean water entering the sea floor would be too low relative to the cleaning effects of the water energy to cause clogging.
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REFERENCES
EKI, 28 March 2017, Comments Regarding California America Water Monterey Peninsula Water Supply Project Draft Environmental Impact Report/Environmental Impact Statement, Released 13 January 2017, Memorandum to Marina Coast Water District.
ESA, April 2015, Cal Am Monterey Water Supply Project, Draft Environmental Impact Report, prepared for California Public Utilities Commission.
ESA, January 2017, Cal Am Monterey Water Supply Project, Draft Environmental Impact Report, prepared for California Public Utilities Commission.
GeoHydros, 27 March 2017, Review of the 2016 North Marina Groundwater Model, prepared for Marina Coast Water District.
Goebel M, A Pidlisecky, R Knight, 2017, Resistivity imaging reveals complex pattern of saltwater intrusion along Monterey coast, Journal of Hydrology, vol. 551, pp 746-755. http://www.sciencedirect.com/science/article/pii/S0022169417301154?via%3Dihub
Geoscience, 8 July 2014, Monterey Peninsula Water Supply Project Results of Test Slant Well Predictive Scenarios Using CEMEX Area Model, DRAFT, prepared for Cal Am Water, Appendix E1 of DEIR.
Geoscience, 8 July 2014, Technical Memorandum (TM1) Summary of Results – Exploratory Boreholes, Monterey Peninsula Water Supply Project Hydrogeologic Investigation, DRAFT, prepared for Cal Am Water and RBF Consulting, Appendix C3 of DEIR
Geoscience, 17 April 2014, Monterey Peninsula Water Supply Project Groundwater Modeling and Analysis, prepared for Cal Am Water, Appendix E2 of DEIR.
Geoscience, 20 April 2014, Technical Memorandum, Monterey Peninsula Water Supply Project Baseline Water and Total Dissolved Solids Levels, Test Slant Well Area, submitted to the Hydrogeologic Working Group.
Geoscience, 16 June 2015, Test Slant Well Long Term Pumping Monitoring Report No. 7, 3 June 15 to 10 June 15, prepared for Cal Am Water http://www.watersupplyproject.org/testwellmonitoring
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Geoscience Support Services Inc., 2016, “DRAFT Monterey Peninsula Water Supply Project Hydrogeologic Investigation Technical Memorandum (TM2) Monitoring Well Completion Report and CEMEX Model Update, prepared for Cal Am Water, 15 July 2016.
Geoscience Support Services Inc., 2017, Monterey Peninsula Water Supply Project Test Slant Well Long Term Pumping Monitoring Report No. 114 5-July-17 – 12-July-17, prepared for Cal Am Water, 18 July 2017. https://www.watersupplyproject.org/test-well
Guo, W. and C.D. Langevin, 2002. “User’s Guide to SEAWAT: A Computer Program for Simulation of Three-Dimensional Variable-Density Ground-Water Flow.” U.S. Geological Survey Techniques of Water-Resources Investigations 6-A7.
Harbaugh, A.W., 2005, MODFLOW-2005, The U.S. Geological Survey modular ground-water model – the Ground-Water Flow Process (TM 6-A16) (see also http://water.usgs.gov/ogw/modflow/).
Hopkins, 29 March 2017, letter to Marina Coast Water District, re: CalAm Monterey Peninsula Water Supply Project, Draft Environmental Impact Report/Environmental Impact Statement, Prepared for California Public Utilities Commission and Monterey Bay National Marine Sanctuary, January 2017
HydroFocus, 2016, North Marina Groundwater Model Review, Revision, and Implementation for Slant Well Pumping Scenarios, 23 Nov 2016, Appendix E2 of RDEIR.
LBNL, 2016, Peer Review of Groundwater Modeling for the Monterey Peninsula Water Supply Project (MPWSP) April 2015 Draft EIR, Lawrence Berkeley National Laboratory, LBNL-1006421, 31 Oct 2016, included as Appendix E1 in the RDEIR.
Marina Coast Water District (MCWD), Monterey County Water Resources Agency (MCWRA), and California-American Water Company (Cal-Am), 2010. Water Purchase Agreement. Dated April 6, 2010.
Mactec, 2006, Final Operable Unit Carbon Tetrachloride Plume Groundwater Remedial Investigation/Feasibility Study, Former Fort Ord, California, Volume 1 – Remedial Investigaiton, prepared for the US Army Corps of Engineers, May 19. http://fortordcleanup.com/reference-documents/ouctp/
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Montgomery Watson, 1994, Salinas River Basin Water Resources Management Plan task 1.09, Salinas Valley Ground Water Flow and Quality Model Report, prepared for MCWRA.
Regional Water Quality Control Board, Central Coast Region, State Water Resources Control Board, California Environmental Protection Agency, (RWQCB, 2011), Water Quality Control Plan for the Central Coastal Basin, Dated June.
Regional Water Quality Control Board, Central Coast Region, Revised Waste Discharge Requirements Order No. R3-2006-0017, Waste Discharger ID No. 3 270303001 for Monterey Regional Waste Management District, Monterey Peninsula Class III Landfill Monterey County.
Sobczynski, L., 2017, Comments on the Draft Environmental Impact Report/Draft Environmental Impact Statement for the Proposed Monterey Peninsula Water Supply Project, letter from the law firm of Adams Broadwell Joseph & Cardozo on behalf of California Unions for Reliable Energy (CURE) to the California Public Utilities Commission and Monterey Bay National Marine Sanctuary. March 28.
State Water Resources Control Board, 2013, Final Review of California American Water Company’s Monterey Peninsula Water Supply Project, 31 July, included as Appendix B2 to RDEIR.
Review of the NMGWM – 2016 Version
GeoHydros 21 | P a g e
Figure 10. Comparison of simulated drawdown in in the Dune Sand Aquifer (Layer 2) derived from the calibrated version of the
2016 version of the NMGWM (top) and the Superposition model (bottom).
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Review of the NMGWM – 2016 Version
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Figure 11. Comparison of simulated drawdown in in the 180-FT Aquifer (Layer 4) derived from the calibrated version of the
NMGWM-2016 (top) and the Superposition model (bottom).
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Review of the NMGWM – 2016 Version
GeoHydros 23 | P a g e
Figure 12. Comparison of simulated drawdown in in the 400-FT Aquifer (Layer 6) derived from the calibrated version of the
NMGWM-2016 (top) and the Superposition model (bottom).
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Armstrong Ranch location, flow arrows, and notes added to DRAFT Figure 137 from Appendix E2 of DEIR
Armstrong Ranch
Armstrong Ranch is well beyond extent of capture by the proposed project pumping.
ATTACHMENT 2
Existing conditions. Inland flow direction in coastal aquifers.
With project pumping. Local reversal of flow direction toward the coast.
