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Notification of Intent to Initiate Closure of Inactive Impoundments 1, 2, and 3A
MidAmerican Energy Company, Neal North Energy Center
Revision 0 October 16, 2015
Notification of Intent to Initiate Closure of Inactive Impoundments 1, 2, and 3A
Prepared for
MidAmerican Energy Company, Neal North Energy Center
Sergeant Bluff, Iowa
Revision 0 October 16, 2015
Prepared by
Burns & McDonnell Engineering Company, Inc. Kansas City, Missouri
COPYRIGHT © 2015 BURNS & McDONNELL ENGINEERING COMPANY, INC.
Impoundments 1, 2, and 3A – Notification of Intent to Close Table of Contents
MidAmerican Energy Company TOC-1 Burns & McDonnell
TABLE OF CONTENTS
Page No.
1.0 SUMMARY OF OBJECTIVES .......................................................................... 1-1
2.0 GENERAL CONDITIONS ................................................................................. 2-1
3.0 CLOSURE PLAN .............................................................................................. 3-1
3.1 Cover System ....................................................................................................... 3-2
4.0 CLOSURE SCHEDULE .................................................................................... 4-1
5.0 CLOSURE NOTICES AND PROGRESS REPORTS ........................................ 5-1
APPENDIX A – GENERAL SITE PLAN
APPENDIX B – FINISH GRADING PLAN
APPENDIX C – PRELIMINARY WORK SCHEDULE
Impoundments 1, 2, and 3A – Notification of Intent to Close List of Abbreviations
MidAmerican Energy Company i Burns & McDonnell
LIST OF ABBREVIATIONS
Abbreviation Term/Phrase/Name
ASTM American Society for Testing and Materials
CCR Coal Combustion Residual
CFR Code of Federal Regulations
CQA Construction Quality Assurance
CU YD Cubic Yards
EPA Environmental Protection Agency
MEC MidAmerican Energy Company
U.S.C. United States Code
RCRA Resource Conservation and Recovery Act
Impoundments 1, 2, and 3A – Notification of Intent to Close Summary of Objectives
MidAmerican Energy Company 1-1 Burns & McDonnell
1.0 SUMMARY OF OBJECTIVES
On April 17, 2015, the Environmental Protection Agency (EPA) issued the final version of the Federal
Coal Combustion Residual (CCR) Rule to regulate the disposal of coal combustion residual materials
generated at coal-fired units. The rule will be administered as part of the Resource Conservation and
Recovery Act [RCRA, 42 United States Code (U.S.C.) §6901 et seq.], using the Subtitle D approach.
The purpose of this document is to indicate the intent of MidAmerican Energy (MEC) to initiate closure
of the existing, inactive CCR Surface Impoundments 1, 2, and 3A (Impoundments 1, 2, and 3A) at the
Neal North Energy Center. This document is also a declaration that Impoundments 1, 2, and 3A are
inactive (not receiving CCR) and closing pursuant to the CCR Rule with closure completion on or before
April 17, 2018. The intent to initiate closure of inactive CCR surface impoundments must contain the
following per 40 Code of Federal Regulations (CFR) 257.100(c)(1), §257.100(b)(4) and §257.100(b)(6):
• Declaration that CCR surface impoundment is inactive
• Declaration that CCR surface impoundment is closing
• Narrative description indicating how the CCR surface impoundment will be closed
• Schedule for completing closure activities
• Certification from a qualified professional engineer stating that the design of the final cover
system meets applicable requirements
• Certification from a qualified professional engineer that closure of the CCR surface
impoundment is technically feasible by April 17, 2018
Impoundments 1, 2, and 3A – Notification of Intent to Close General Conditions
MidAmerican Energy Company 2-1 Burns & McDonnell
2.0 GENERAL CONDITIONS
After conducting a preliminary study to review existing conditions, to review current plant operations,
and to identify a recommended closure plan for the existing CCR surface impoundment at the Neal North
Energy Center, Burns & McDonnell was retained to provide permit support and engineering design for
the closure of Impoundments 1, 2, and 3A. The existing surface impoundments, Impoundments 1, 2, and
3A, which no longer receive CCR material, will be closed by leaving material in place, per 40 CFR
§257.100(b)(1). To support future plans at the Neal North Energy Center, a portion of Impoundment 1
will be closed by removal of material.
Impoundments 1, 2, and 3A are located at the Neal North Energy Center site, near Sergeant Bluff, Iowa.
The Missouri River is located directly west of Impoundment 1. See SK007, Appendix A. Impoundment 1
is approximately 13 acres, Impoundment 2 is approximately 19 acres, and Impoundment 3A is
approximately 48 acres. Bordering Impoundment 3A on the east, is existing CCR Surface Impoundment
3B. Impoundment 3B will remain active after the effective date of the CCR Rule, October 19, 2015, and
is therefore not discussed further in this document. The main type of CCR material present in
Impoundment 1 is bottom ash, while Impoundments 2 and 3A contain fly ash, bottom ash, and
economizer ash.
Impoundments 1, 2, and 3A – Notification of Intent to Close Closure Plan
MidAmerican Energy Company 3-1 Burns & McDonnell
3.0 CLOSURE PLAN
The inactive impoundments at Neal North Energy Center will be closed with CCR material remaining in
place. This closure method will be referred to as “cap-in-place,” herein. The closure plan for
Impoundments 1, 2, and 3A will require drainage (unwatering of free water and dewatering of entrained
water) and stabilization of the existing CCR material prior to and during excavation and fill operations.
To minimize the volume of general fill imported to the project site from an off-site borrow source, Burns
& McDonnell chose to use existing CCR material from Impoundment 1 as general fill for Impoundments
2 and 3A. CCR material from a portion of Impoundment 1 will be completely removed, so the area will
be “clean-closed.” A temporary berm will be installed during construction, between Impoundments 1 and
2, to prevent migration of CCR material from the cap-in-place portion to the clean-closed portion.
Approximately 110,700 cubic yards (CU YD) of material from Impoundment 1 will be consolidated to
Impoundments 2 and 3A. Furthermore, approximately 62,800 CU YD of material will be cut from within
Impoundments 2 and 3A and re-compacted in areas within the impoundments to obtain proper slope.
When the CCR material is relocated, and placed “in mass,” it will be placed in loose lifts of uniform
thickness and compacted to a specified density.
To ensure all existing CCR material is removed from the portion of Impoundment 1 that is to be clean-
closed, the existing subgrade will be over-excavated by an additional 6-inches. The over-excavated
material will be used as additional general fill in Impoundments 2 and 3A. The bottom of Impoundment
1will be established through original design drawings, geotechnical boring logs, and visual observation
during impoundment closure construction activities.
The cap-in-place portion of the closure site covering Impoundments 2 and 3A will be split into three
regions because of necessary high points caused by existing transmission lines and a future monofill haul
road (see SK008 in Appendix B). Upon completion of closure, the three regions will have been graded to
low points, where culverts will allow water to drain off the covered portion of the impoundments to an
existing outfall channel.
The clean-closed portion of Impoundment 1 will be filled in with general fill material, imported from an
off-site borrow source, so as not to pond water. An additional 6,500 CU YD of general fill material will
be imported to achieve the necessary final grades. All imported general fill material will be free of roots,
organic matter, and any other unsuitable material. The general fill material will be placed in a maximum
of 8-inch loose lifts, and will be compacted to not less than 95 percent of the maximum dry density, with
a moisture content within 3 percent of optimum levels. Once the grade of the clean-closed area is
Impoundments 1, 2, and 3A – Notification of Intent to Close Closure Plan
MidAmerican Energy Company 3-2 Burns & McDonnell
established, it will be covered with a 6-inch thick erosion control layer and quick-growth, native grass
seed to establish vegetation. Manufactured erosion control materials may be used to limit erosion and aid
in vegetation growth.
3.1 Cover System
The closure plan will require the installation of a final cover system over the CCR material that will be
left in place, to minimize erosion and infiltration. A typical cross section of the cover system is shown in
Figure 3-1.
Figure 3-1: Typical Cover System
The typical final cover system will consist of an 18-inch thick, earthen, infiltration (clay) layer, with an
erosion layer that contains 6 inches of earthen material that is capable of sustaining native plant growth.
The federal minimum standard requires the cover system’s permeability to be less than or equal to that of
the bottom liner or natural subsoils present, or 1 x 10-5
centimeters/second, whichever is less.
A portion of the natural subsoils in Impoundment 3A consists of clays with probable permeability values
at or below 1 x 10-5 centimeters/second. However, this is not a continuous or homogenous layer, and is
surrounded by sandy and silty soils. Therefore, due to the absence of an existing liner system in
Impoundments 1, 2, and 3A, and because only a small portion of the overall natural subsoils are
comprised of clay, the cover system will meet the 1 x 10-5
centimeters/second criteria. The required
permeability values will be achieved through the use of clay with properties meeting the developed
specification criteria. Approximately168,500 CU YD of infiltration layer material will be imported to
complete the cover system.
The infiltration layer will be constructed in maximum 10-inch thick loose lifts of material, and compacted
to a minimum of 6 inches per lift. During installation of the infiltration layer, proper quality control
methods will be used. A construction quality assurance (CQA) plan will be compiled and implemented to
ensure the following:
Impoundments 1, 2, and 3A – Notification of Intent to Close Closure Plan
MidAmerican Energy Company 3-3 Burns & McDonnell
• The selected infiltration layer material is suitable,
• The material meets the minimum federal thickness and permeability requirements,
• The material is properly placed and compacted,
• The infiltration layer is properly protected before, during, and after construction, and
• The erosion layer is seeded with native vegetation.
The hydraulic conductivity of the infiltration layer will be verified through testing in accordance with the
American Society for Testing and Materials (ASTM) Standard D5084. The thickness of the infiltration
layer will be verified through topographical surveys before and after installation of the layer.
Figure 3-1 indicates the use of a six-inch thick topsoil and seed layer above the 18-inch infiltration layer.
This layer will act as an erosion control layer that will sustain plant growth with the intent of reducing
erosion. Approximately 56,200 CU YD of erosion control layer material will be imported to complete the
cover system.
The final cover system grade will slope at a minimum of 1.5 percent over the impoundment surface to
prevent the collection of standing water, and limit the velocity of storm water runoff to reduce the
potential for soil erosion. The period of time for greatest soil erosion concern will be immediately after
placement of the topsoil material, before vegetation is established. Manufactured erosion control
products, as well as a seed mix containing quick-growth seed varieties, will aid in erosion prevention
during this critical timeframe.
Settling and subsidence of the final cover system is anticipated. Settlement would be caused by
consolidation of the existing CCR material, backfilled CCR material, or underlying natural subsoils under
new loads from grading activities. Saturated, softer existing CCR material will settle under the additional
loading of construction activities. However, this settlement will occur for the duration of grading
activities and is expected to be minimal after the infiltration layer is installed. Backfill of CCR material
will be constructed in a controlled manner to minimize post-cover installation settlement. Lastly, the
underlying natural subsoils at the site consist of both sand and clay. Underlying sands are not prone to
long-term settlement. Under additional loading from grading activities, the clay subsoils may settle over
time. However, this settlement will be widespread, reducing the effect of differential settlement.
Mass stability of the cap-in-place material will be analyzed after completion of the final design, which is
currently ongoing. If the mass stability safety factor is unacceptable, modifications to the final design will
be made. Based on the relatively shallow sloping grades anticipated to be used in the design, the mass
stability safety factor is anticipated to be acceptable. Instability of the cover system is not anticipated,
Impoundments 1, 2, and 3A – Notification of Intent to Close Closure Plan
MidAmerican Energy Company 3-4 Burns & McDonnell
based on the relatively shallow sloping grades and the use of only clay material in the cover system (no
geosynthetics). The stable cover system design concept will minimize the need for extensive future
maintenance of the closed Impoundments 1, 2, and 3A.
Impoundments 1, 2, and 3A – Notification of Intent to Close Closure Schedule
MidAmerican Energy Company 4-1 Burns & McDonnell
4.0 CLOSURE SCHEDULE
Per 40 CFR §257.100(b) of the CCR Rule, the deadline to complete closure of inactive surface
impoundments is April 17, 2018. Burns & McDonnell has developed a preliminary work schedule based
on the completion date of no later than April 17, 2018.
The preliminary work schedule was created by applying labor output rates to quantities of construction
materials and labor activities, to determine feasible activity durations. The labor output rates were
identified using the 29th Annual Edition of RSMeans Heavy Construction Cost Data, for 2015. Burns &
McDonnell made assumptions of feasible crew numbers, based on the size of the work site as well as
previous project experience. The crew size assumptions reference the number of pieces of equipment that
will be onsite during construction of the closure of Impoundments 1, 2, and 3A, and are as follows:
• 3 excavators
• 4 haul trucks (12-CU YD) for moving material around the site
• 15 haul trucks (18-CU YD) for importing material from offsite
• 4 dozers
• 2 compactors
• 2 seeding crews
The preliminary schedule was mindful of increased difficulty of work and decreased production during
winter months. Contractors that are specialized in unwatering and dewatering work estimated the
durations of the respective activities. These contractors indicated unwatering and dewatering work could
be completed year round. Activities such as installation of the 18-inch infiltration layer, installation of the
6-inch erosion control layer, and seeding will not be completed during mid-November to mid-March.
As evidenced by the preliminary work schedule, included in Appendix C, completion of the closure of
Impoundments 1, 2, and 3A prior to April 17, 2018 is technically feasible.
Impoundments 1, 2, and 3A – Notification of Intent to Close Closure Notices and Progress Reports
MidAmerican Energy Company 5-1 Burns & McDonnell
5.0 CLOSURE NOTICES AND PROGRESS REPORTS
There are several closure notices and progress reports that will be required throughout Impoundments 1,
2, and 3A closure process according to 40 CFR §257.100(c). Closure documentation will include the
following (CCR Rule compliance dates in parentheses):
• The notification of intent to close an inactive surface impoundment (this document) is required by
the CCR Rule on December 17, 2015.
o MEC, however, plans to place this document in the CCR Operating Record on October 19,
2015, with notification sent to the Iowa Department of Natural Resources’ Director on the
same day.
• The annual progress reports summarizing closure progress and projected closure activities:
o The first annual progress report shall be completed 13 months after completing the
notification of intent to close document, or on January 17, 2017, per the CCR Rule.
− The first annual progress report will be required to be completed on November 19, 2016,
based on placing the intent to close document in the CCR Operating Record on October
19, 2015.
o The second annual progress report shall be completed 12 months after completing the first
annual progress report, or by January 17, 2018, per the CCR Rule.
− The second annual progress report will be required to be completed on November 19,
2017, based on placing the intent to close document in the CCR Operating Record on
October 19, 2015.
• Notification of completion of closure should be completed within 60 days of the actual closure
completion.
The closure notices and progress reports will be placed in MEC’s Operating Record, will be sent to the
Iowa Department of Natural Resources’ Director before close of business on the respective compliance
dates, and will be placed on MEC’s CCR public website within 30 days of placing said information in the
Operating Record.
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NEAL NORTHMIDAMERICAN ENERGY COMPANY
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NEAL NORTHMIDAMERICAN ENERGY COMPANY
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SCALE IN FEET
300' 600'0 NORTH
PARTIAL CLEAN CLOSURE
SLP=1.50
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IMPORT 6" EROSION CONTROL LAYER
QUANTITY (CU YD)
IMPORT 18" INFILTRATION LAYER
62,800
CCR FILL FROM CLEAN CLOSED PORTION
168,500
56,200
110,700
CAP-IN-PLACE PORTION
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EXISTING CONTOURS
CULVERT W/ END SECTION
NEW CONTOURS1090PORTIONCLEAN CLOSURE
CAP-IN-PLACE PORTION
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OR REMOVEDBE ABANDONEDCULVERTS TOEXISTING
(48 ACRES)IMPOUNDMENT 3AEXISTING
(19 ACRES)IMPOUNDMENT 2EXISTING
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(13 ACRES)IMPOUNDMENT 1EXISTING
COVER)(TO RECEIVEEMBANKMENTHAUL ROAD
HAUL ROADFUTURE MONOFILL
LINE CORRIDORTRANSMISSIONEXISTING
Activity ID Activity Name OD Start Finish TotalFloat
MEC NEAL CCR ComplianceMEC NEAL CCR Compliance 754 24-Apr-15 A 17-Apr-18 0
CCR Surface Impoundment Closure (1, 2, 3A)CCR Surface Impoundment Closure (1, 2, 3A) 599 04-Dec-15 17-Apr-18 0
BMIC-280 Evaluate and Award Dewatering package 15 04-Dec-15 28-Dec-15 101
BMIC-170 Issue detailed CCR Surface Impoundment closure drawings (Issued for Bid) 10 21-Jan-16 03-Feb-16 120
BMIC-180 Bid, Evaluate, award proposals for CCR Surface Impoundment closure 40 04-Feb-16 30-Mar-16 120
BMIC-190 Mobilization to site for CCR Surface Impoundment closure 15 31-Mar-16 20-Apr-16 120
BMIC-290 Dewatering Impoundment 2 and 3A 80 27-Jan-16 17-May-16 101
BMIC-194 Cut to Fill & Compact all CCR from Impoundment 1 90 21-Apr-16 26-Aug-16 155
BMIC-191 Place Fill for New Monofill Haul Road 60 09-Jun-16 01-Sep-16 201
BMIC-200 Cut to Fill & Compact CCR within Impoundments 2 & 3A 125 18-May-16 11-Nov-16 101
BMIC-192 Install Culverts for Post-Closure Drainage 60 02-Sep-16 29-Nov-16 201
BMIC-195 Over Excavation 6" of Exist. Impoundment 1 Subgrade 70 29-Aug-16 07-Dec-16 165
BMIC-196 Cut to Fill & Compact for Clean-Closed Final Grading 30 08-Dec-16 23-Jan-17 165
BMIC-197 Import General Fill Material for Clean-Closed Final Grading 10 24-Jan-17 06-Feb-17 273
BMIC-198 Finish Grading Clean-Closed Area 15 07-Feb-17 27-Feb-17 273
BMIC-202 Install 6" Erosion Control Layer on Clean-Closed Area 10 13-Mar-17 24-Mar-17 184
BMIC-203 Seeding Clean-Closed Area 5 27-Mar-17 31-Mar-17 184
BMIC-193 Pave Haul Road 20 13-Mar-17 07-Apr-17 131
BMIC-201 Finish Grading - Prepare Surface for 18" Infiltration Layer (Impoundment 2 & 3A) 50 13-Mar-17 19-May-17 21
BMIC-210 Installation 18" Infiltration Layer (Impoundment 2 & 3A) 115 20-Mar-17 29-Aug-17 21
BMIC-220 Installation 6" Erosion Control Layer (Impoundment 2 & 3A) 40 16-Aug-17 11-Oct-17 21
BMIC-230 Seeding Complete (Impoundment 2 & 3A) 25 14-Sep-17 18-Oct-17 21
BMIC-270 Submit NPDES Certificate of Completion 23 19-Oct-17 20-Nov-17 101
MS3-1120 Deadline to complete closure of inactive CCR Surface Impoundments 1, 2, and 3A 0 17-Apr-18* 0
Impoundment Unwatering (2, 3A)Impoundment Unwatering (2, 3A) 74 08-Oct-15 26-Jan-16 101
BMPD-250 Evaluate and Award Impoundment 3A Unwatering package 5 08-Oct-15 14-Oct-15 0
BMPD-260 Plug Impoundment 3A culverts and stage unwatering equipment 3 15-Oct-15 19-Oct-15 0
BMPD-270 Unwatering surface water from Impoundment 3A 19 20-Oct-15 13-Nov-15* 0
BMPD-160 Unwatering surface water from Impoundment 2 (Pred to Act ID BMPR-180) 20 29-Dec-15 26-Jan-16 101
Piping Reroutes from CCR Surface Impoundments (1, 2, 3A)Piping Reroutes from CCR Surface Impoundments (1, 2, 3A) 190 24-Apr-15 A 26-Jan-16 101
BMPR-110 BMCD Identify pipe Modifications to re-route U1/U2 Ash Piping to CCR Surface Impoundment 3B 38 24-Apr-15 A 17-Jun-15ABMPR-130 Design Piping Reroutes and issue IFC 10 18-Jun-15 A 01-Jul-15 A
BMPR-170 Install piping and modify ash handling equipment 41 05-Aug-15 A 30-Sep-15 13
MS3-1010 Cease CCR discharge to Inactive CCR Surface Impoundments (1, 2, 3A) 0 19-Oct-15* 0
BMPR-180 Re-route Landfill Leachate pipe to Impoundment 3B (Pred to BMPD-170) 20 29-Dec-15 26-Jan-16 101
Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct NovDec
2015 2016 2017 2018 2019
Evaluate and Award Dewatering package
Issue detailed CCR Surface Impoundment closure drawings (Issued for Bid)
Bid, Evaluate, award proposals for CCR Surface Impoundment closure
Mobilization to site for CCR Surface Impoundment closure
Dewatering Impoundment 2 and 3A
Cut to Fill & Compact all CCR from Impoundment 1
Place Fill for New Monofill Haul Road
Cut to Fill & Compact CCR within Impoundments 2 & 3A
Install Culverts for Post-Closure Drainage
Over Excavation 6" of Exist. Impoundment 1 Subgrade
Cut to Fill & Compact for Clean-Closed Final Grading
Import General Fill Material for Clean-Closed Final Grading
Finish Grading Clean-Closed Area
Install 6" Erosion Control Layer on Clean-Closed Area
Seeding Clean-Closed Area
Pave Haul Road
Finish Grading - Prepare Surface for 18" Infiltration Layer (Impoundment 2 & 3A)
Installation 18" Infiltration Layer (Impoundment 2 & 3A)
Installation 6" Erosion Control Layer (Impoundment 2 & 3A)
Seeding Complete (Impoundment 2 & 3A)
Submit NPDES Certificate of Completion
Deadline to complete closure of inactive CCR Surface Impoundments 1, 2, and 3A
Evaluate and Award Impoundment 3A Unwatering package
Plug Impoundment 3A culverts and stage unwatering equipment
Unwatering surface water from Impoundment 3A
Unwatering surface water from Impoundment 2 (Pred to Act ID BMPR-180)
BMCD Identify pipe Modifications to re-route U1/U2 Ash Piping to CCR Surface Impoundment 3B
Design Piping Reroutes and issue IFC
Install piping and modify ash handling equipment
Cease CCR discharge to Inactive CCR Surface Impoundments (1, 2, 3A)
Re-route Landfill Leachate pipe to Impoundment 3B (Pred to BMPD-170)
Start Date 22-Apr-15
Finish Date 17-Oct-24
Data Date 17-Sep-15
Run Date 02-Oct-15
MidAmerican Energy
Neal Energy Center
CCR Compliance CCR Surface Impoundments 1, 2, 3A Closure
Page 1 of 1
Date Revision Checked Approved
02-Oct-15 Issed for Owner A.Hamawi