HomeMy Public PortalAboutExhibit MSD 50C3 - 2015 Update (LTCP) - Modifications A & BExhibit MSD 50C3
CHIEF, WATER ENFORCEMENT AND COMPLIANCE ASSURANCE BRANCH FEBRUARY 4, 2015
WATER AND WETLANDS PROTECTION DIVISION PAGE 2
U.S. ENVIRONMENTAL PROTECTION AGENCY - REGION 7
Non -Material Modification A
Non -Material Modification A, as further described in Attachment A, will affect two (2) of the
CSO Control Measures listed on Page 6 of Appendix D to the Consent Decree.
The first CSO Control Measure is identified as "In -sewer Storage Upstream of Lemay CSO
Outfall 063." The intent of this Control Measure was to provide 25 million gallons of storage
capacity within the existing sewer system upstream of Lemay CSO Outfall 063 by means of an
inflatable or moveable dam system.
MSD proposes to eliminate this CSO Control Measure by increasing the storage volume of the
"Lower & Middle River Des Peres Storage Tunnel" by the said 25 million gallons. MSD's
proposal is based on new information developed since the entry of the Consent Decree, provides
additional environmental benefits while reducing other risks, and reflects good engineering
practice.
This change will only affect the Design Criteria for the "Lower & Middle River Des Peres
Storage Tunnel" by increasing the storage volume (at least 25 million additional gallons) from
the originally proposed 206 million gallons (Le., a less than 20% modification of Design
Criteria). Most importantly, it will not change the Performance Criteria and Critical Milestones
associated with the "Lower & Middle River Des Peres Storage Tunnel"
Locating all of the required CSO storage volume to the Lower & Middle River Des Peres
Storage Tunnel will also provide an additional environmental benefit. Under the originally
proposed CSO Control Measures, the 25 million gallons of in -sewer storage would be useable
only when it rams in the upper portion of the combined sewer area (i.e., upstream of Outfall
063). By relocating the 25 million gallons of storage volume to the downstream tunnel, this
volume can be utilized regardless of whether or not it is raining in the Lemay combined sewer
area served by the tunnel.
For the foregoing reasons, MSD respectfully requests that EPA approve Non -Material
Modification A.
Non -Material Modification B
Non -Material Modification B, as further described in Attachment B, will affect the three (3)
following CSO Control Measures listed on Pages 3, 5, and 6 of Appendix D to the Consent
Decree:
Upper River Des Peres Storage Tunnel serving Lemay Outfalls 064, 066 to 096, 099 to
102, 167, 178 and 180.
• River Des Peres Tributaries Storage Tunnel serving Lemay CSO Outfalls 103, 104, 105,
106, 111, 117 to 128, 130, 131, 134, 136 to 140, 166 and 176.
CHIEF, WATER ENFORCEMENT AND COMPLIANCE ASSURANCE BRANCH
WATER AND WETLANDS PROTECTION DIVISION
U.S. ENVIRONMENTAL PROTECTION AGENCY - REGION 7
FEBRUARY 4, 2015
PAGE3
• Lower & Middle River Des Peres Storage Tunnel serving Lemay CSO Outfalls 008 to
032, 036, 037, 039, 041 to 044, 048, 050, 052, 053, 054, 057, 058, 061, 063, 163, 170 to
173, and 181.
MSD proposes that the Design Criteria for each of these three Control Measures be modified by
deleting the "to capture flows from Lemay CSO OutfaIls..." wording, as more particularly
described in Attachment B. Alternatively, MSD requests that the Consent Decree be clarified to
allow MSD to use other design methods, so long as they reflect good engineering practice, in
order to satisfy the specified Performance Criteria and Critical Milestones. This modification or
clarification, if approved, will not change the Performance Criteria and Critical Milestones.
MSD believes that this modification or clarification is necessary because the current wording
could be interpreted as requiring each and every one of the named CSO Outfalls to be physically
connected to the storage tunnel. This was neither the intent of the Long -Term Control Plan
(LTCP) nor the Consent Decree. The parties to the LTCP and the Consent Decree recognized
that MSD could utilize other acceptable design methods (i.e., other than "capture"), so long as
they reflected good engineering practice and achieved the requisite Performance Criteria and
Critical Milestones. Without this change, it will remain unclear as to whether MSD will have to
request a modification to the Consent Decree every time that a different yet acceptable control
technique is selected during the final design.
In order to achieve clarity and efficiency, MSD respectfully requests that EPA approve Non -
Material Modification B.
Furthermore, if Non -Material Modification A and B are approved by September 1, 2015, these
modifications will allow MSD to meet the Critical Milestone Dates specified in Appendix D to
the Consent Decree. Demonstrating good engineering practice, the proposed modifications will
also provide additional environmental benefits, reduce project risks, and allow the best
engineering solutions to be applied at each CSO Outfall. For these and other reasons as outlined
in the attached documents, MSD believes that the proposed modifications should be approved by
EPA.
Enclosed and hereby incorporated with this letter you will find the following: (1) a Proposal
Document providing a detailed explanation of the proposed modifications, along with relevant
information demonstrating that the proposed modifications reflect good engineering practices
and will continue to achieve the required Performance Criteria (as specified in Appendix D for
these CSO Control Measures); and (2) a red -lined version of relevant portions of the Consent
Decree (Appendix D and Appendix E) delineating the proposed modifications to the Consent
Decree.
Through coordinated effort between MSD and EPA, MSD has confidence that these proposed
modifications can be discussed and resolved expeditiously so that MSD can continue to meet its
Critical Milestone dates. As such, MSD would like to schedule a meeting between your office
and MSD technical staff to discuss any technical questions and to formulate a process for
moving this matter forward. We will contact your office immediately for help coordinating a
meeting.
CHIEF, WATER ENFORCEMENT AND COMPLIANCE ASSURANCE BRANCH
WATER AND WETLANDS PROTECTION DIVISION
U.S. ENVIRONMENTAL PROTECTION AGENCY - REGION 7
FEBRUARY 4, 2015
PAGE 4
If you should have any questions with regard to this matter, please feel free to contact me.
Sincerely,
ik /0: 76/0.)------.N
Susan M. Myers
General Counsel
cc. Brad Nevois, MSD
Patricia Pride, MSD
CHIEF, WATER ENFORCEMENT AND COMPLIANCE ASSURANCE BRANCH
WATER AND WETLANDS PROTECTION DIVISION
U.S. ENVIRONMENTAL PROTECTION AGENCY - REGION 7
FEBRUARY 4, 2015
PAGE 5
Consent Decay Communication Distribution Ito
United States:
Chief, Environmental Enforcement Section
Environment and Natural Resources Division
U.S. Department of Justice
Box 7611 Ben Franklin Station
Washington, D.C. 20044-7611
Re: DOJ No. 90-5-1-1-08111
EPA:
Chief, Water Enforcement and Compliance
Assurance Branch
Water and Wetlands Protection Division
U.S. Environmental Protection Agency,
Region 7
11201 Renner Blvd.
Lenexa, KS 66219
State of:Missouri:
David Cozad
Regional Counsel
Office of Regional Counsel
U.S. Environmental Protection Agency,
Region 7
11201 Renner Blvd.
Lenexa, KS 66219
Chief Counsel
Agriculture and Environment Division
State of Missouri Office of Attorney General
207 W. High Street
Jefferson City, MO 65102
Chief, Water Pollution Compliance and
Enforcement Section
Missouri Department of Natural Resources
P.O. Box 176
1101 Riverside Dr.
Jefferson City, MO 65101
Director, St. Louis Regional Office
Missouri Department of Natural Resources
7523 South Lindbergh Blvd.
St. Louis, MO 63125
Coalition:
Heather B. Navarro
Executive Director
Missouri Coalition for the Environment
3115 S. Grand Blvd., Suite 650
St. Louis, MO 63118
Maxine I. Lipeles
Elizabeth J. Hubertz
Interdisciplinary Environmental Clinic
Washington University School of Law
One Brookings Drive
Campus Box 1120
St. Louis, MO 63130
MSD:
Executive Director
Metropolitan St. Louis Sewer District
2350 Market Street
St. Louis, MO 63103-2555
Director of Engineering
Metropolitan St. Louis Sewer District
2350 Market Street
St. Louis, MO 63103-2555
General Counsel
Metropolitan St. Louis Sewer District
2350 Market Street
St. Louis, MO 63103-2555
February 4, 2015 ATTACHMENT A Page 1 of 4
Metropolitan St. Louis Sewer District
Proposed Revision of CSO Control Measures:
In -Sewer Storage Upstream of Lemay CSO Outfall 063
and Lower & Middle River Des Peres Storage Tunnel
The Metropolitan St. Louis Sewer District ("MSD") hereby requests that the U.S. Environmental
Protection Agency ("EPA") approve the modification of the Design Criteria for two CSO
Control Measures pursuant to Paragraphs 61 and 136 of the April 27, 2012 Consent Decree (Dkt.
#159), as amended by the Court on October 10, 2013 (Dkt. #164) and by agreement on July 5,
2013 (Dkt. #161), in Cause No. 4:07-cv-01120-CEJ. MSD's proposed modifications are
associated with CSOs tributary to the Lower & Middle River Des Peres. MSD herein
demonstrates that the proposed modifications reflect good engineering practice, are based on
new information developed since the entry of the Consent Decree, provide additional
environmental benefits while reducing other risks, and do not change any of the Consent Decree
Performance Criteria or Critical Milestones.
Overview
The proposed modifications affect two of the CSO Control Measures listed on Page 6 of
Appendix D to the Consent Decree (see attached):
• The first CSO Control Measure is "In -sewer Storage Upstream of Lemay CSO Outfall
063." The intent of this Control Measure was to provide 25 million gallons of storage
capacity within the existing sewer system upstream of Lemay CSO Outfall 063 by means
of an inflatable or moveable dam system. MSD proposes to eliminate this CSO Control
Measure by increasing the storage volume of the "Lower & Middle River Des Peres
Storage Tunnel" by the said 25 million gallons.
• This change, of course, affects the Design Criteria for the "Lower & Middle River Des
Peres Storage Tunnel" by increasing the storage volume from the originally proposed
206 million gallons. The increase in the tunnel storage volume represents a revision to the
Design Criteria of less than 20%.
MSD proposes no changes to the Performance Criteria and Critical Milestones associated with
the "Lower & Middle River Des Peres Storage Tunnel."
Details
When the Long -Term Control Plan (LTCP) was originally prepared, it was assumed that the
diameter of the CSO storage tunnel should be limited to less than 30 feet because MSD had not
fully developed its understanding of deep underground conditions along the Lower and Middle
River Des Peres channel where the tunnel would be located. The known presence of karstic
conditions (channels, caves, etc.) in the area was thought to pose a significant challenge to large
diameter tunnel construction. To keep the proposed tunnel diameter within what was believed to
be an appropriate range, the LTCP moved 25 million gallons of the total 231 million gallons of
CSO storage volume required to meet the Performance Criteria to the proposed in -sewer storage
system. The total storage volume of 231 million gallons was thus divided between the deep
tunnel (206 million gallons) and the in -sewer storage system (25 million gallons). The two
February 4, 2015 ATTACHMENT A Page 2 of 4
above -noted Control Measures in Appendix D of the Consent Decree reflect this division of flow
storage.
The LTCP, and subsequent discussions with EPA, MDNR, and the Coalition, reviewed several
potential risks associated with the in -sewer storage. These included the risk of upstream flooding
and potential damage to the 29 -ft horseshoe sewers and tributary sewers upstream of Outfall 063
due to surcharging of the sewers or failure of the storage dam system to operate properly, and the
risk of sedimentation and odors occurring in the 29 -ft horseshoe sewers beneath Forest Park as a
result of the stored flow. MSD noted that these risks could be mitigated but not eliminated.
A better understanding of the geology along the proposed alignment has been developed since
the LTCP was written and the Consent Decree was entered. Three phases of detailed
geotechnical investigations have since been conducted, including 73 deep borings with almost
16,000 feet of rock cored, and extensive geophysical investigations. It is now believed that a
larger -diameter tunnel is feasible at the proposed tunnel depth. The risks of in -sewer storage can
therefore be eliminated by reallocating all of the CSO storage volume required to meet
Performance Criteria to the deep CSO Storage Tunnel.
Locating all of the required CSO storage volume in the tunnel can also provide an additional
environmental benefit. Under the originally proposed CSO Control Measures, the 25 million
gallons of in -sewer storage would be useable only when it rains in the upper portion of the
combined sewer area (i.e., upstream of Outfall 063). By relocating the 25 million gallons of
storage volume to the downstream tunnel, this volume can be utilized regardless of where it is
raining in the Lemay combined sewer area served by the tunnel.
The proposed changes to page 6 of Appendix D, and to page 3 of Appendix E to the Consent
Decree, are noted on the following pages.
February 4, 2015 ATTACHMENT A Page 3 of 4
Case: 4:07-cv-01120-CEJ Doc. #: 159-4 Filed: 04127!12 Page: 6 of 9 Pagela #: 1620
Appendix D
CSO Control Measures, Design Criteria, Performance Criteria, and Critical Milestones
CSO Control Measures — Lower & Middle River Des Peres
CSO C troI
Nicasllr1
Elimination of
Lemay CSO
Ouifalls 046, 049,
168 slid 177
Dc criptlon
Sewer separation
to allow
elimination of
CSO Outfalls
Design Criteria
MSD's Rules and Regulations
and Fi inecnng Design
Requirements for Sanitary
scw�ar and stemmata
Drainage Facilities
Performance
t�ritcr60 Critical f lrIestnnes
Elimination of Lemay
CSO Ou11hlls 046,
049, 168 and 177
• Achievement of Full
Operation— 01101/2011
Lemay CSO
Outfall 062
Elimination
Sewer separation
to allow
elimination of
Lemay CSO
Outfall. 062
MSD's Rules and Regulations
and Engineering Design
Requirements for Sanitary
Sewer and Stamm/afar
Drainage Facilities
Elinnination of Lemay
cs0 outfal1062
• Achievement of Full
Operation— 12/31/2015
CSO
Unit t
300 O.dL.110 3
l hanced High
Rate
Clarification
facility
100 MGD capacity providing
equivalent of pay
clarification, solidslfioatables
disposal, and disinfection
When incorporated
with other River Des
eveSO controls,
reduce overflows to
reduce
4 events or less in the
al rar0.
Comply with
applicable Missouri
Operafiog Permit.
• Bid Year 2027
• Achievement of bill
Operation— 12/31/2030
1n —sewer Storage
Upstream of
Inflatable or
m �llaiAt-.,.r
system to allow
Provide 25 million gallons
within
'him incorporated
withoth
CSO controls,
• Achievement of NE
Lemay CSO
Outfil11063
flow storage in
hotaeahoe sewers
flows from Lemay
CSO Outfall 063 typical
ows to
4 events or less
year0)
Operation -12/31/2030
When incorporated
with other River Des
Peres CSO controls,
reduce overflows to
4 events or less in the
typical yearn!], and
untreated overflow
volume to the River
Des Perri of
1,412 mi Ilion gallons
es--__
T.orvver Be
M
058, 061, 063,
163,170 to 173,
and 181
L
t10 t� ; 4
11
Modifications per Doc. #: 161 Filed: 07/05/13 Page: 3 of 9
Modifications proposed in Attachment B
Modifications proposed in this request
6
February 4, 2015 ATTACHMENT A Page 4 of 4
Case: 4:07-cv-01120-CEJ Doc. #: 159-5 Filed: 04127112 Page: 3 of 6 PagelD #: 1626
APPENDIX E
POST -CONSTRUCTION MONITORING PROGRAM
Mane Creek:
• Ct,-1, i - b-1 Local Storage Facility for Outfalls 051 and 052
Gingras Creek:
• Relocation of Outfall 059
Upper River Des Peres:
• Storage tunnel to store flows from CSO outfalls to the Upper River Des Peres
River Des Peres Tributaries:
• Tunnel to convey/store flows to Lemay WWTF
Lower and Middle River Des Peres:
• Enhanced High Rate treatment unit : »» ^�=-..: '::1 "5?.
• Removalof secondary treatment bottlenecks at WWTF
• Tunnel to convey/stare flows to Lemay WWTF
Following Achievement of Full Operation of each CSO Control Measure listed in
Appendix D, MSD shall conduct activation monitoring at all CSO outfalls addressed by that
particular CSO Control Measure to determine the number of activation events at each CSO
outfall, and submit the activation information in the Annual Report as set forth in Section VIII
of the Consent Decree. Such activation information shall be submitted as an actual number of
events.
III, +mess Tesline of Lewav Treatment Plant
MSD shall construct the CSO Control Measure in accordance with the description, design
criteria, performance criteria, and critical milestones contained in Appendix D to achieve a
minimum secondary treatment design capacity of 210 million gallons per day (MGD) at the
Lemay Treatment Plant. The existing preliminary and primary treatment facilities have a design
capacity of 340 MGD. Effluent disinfection facilities are currently being designed with a
capacity of 340 MGD.
MSD shall submit a stress test protocol to EPA and the State for review and for EPA's
approval, with a copy to the Coalition, at least 30 days prior to Achievement of Full Operation of
the upgraded wastewater treatment facilities. The protocol shall be designed to determine the
maximum treatable wet -weather flow rates for each treatment step (preliminary, primary,
secondary, and disinfection) at the Lemay Treatment Plant following the completion of the
upgrades described above. EPA/MDNR shall review the stress test protocol pursuant to
Section VII of this C-onsent Decree (Review and Approval Procedures).
3
-- Modifications per Doc. #: 164 Filed: 10/10/13 Page: 5 of 11
Modifications per Doc. #: 161 Filed: 07/05/13 Page: 3 of 9
Modifications proposed in this request
February 4, 2015 ATTACHMENT B Page 1 of 5
Metropolitan St. Louis Sewer District
Proposed Revision of CSO Control Measures: Upper
River Des Peres Storage Tunnel, River Des Peres
Tributaries Storage Tunnel, and Lower & Middle
River Des Peres Storage Tunnel
The Metropolitan St. Louis Sewer District ("MSD") hereby requests that the U.S. Environmental
Protection Agency ("EPA") approve the modification of the Design Criteria for three CSO
Control Measures pursuant to Paragraph 61 of the April 27, 2012 Consent Decree (Dkt. #159), as
amended by the Court on October 10, 2013 (Dkt. #164) and by agreement on July 5, 2013 (Dkt.
#161), in Cause No. 4:07-cv-01120-CEJ. MSD's proposed modifications involve the Upper
River Des Peres Storage Tunnel, River Des Peres Tributaries Storage Tunnel, and the Lower &
Middle River Des Peres Storage Tunnel MSD herein demonstrates that the proposed
modifications reflect good engineering practice, are based on new information developed since
the entry of the Consent Decree, may provide additional environmental benefits, and will
continue to achieve the Performance Criteria specified in Appendix D.
Overview
The proposed modifications affect three of the CSO Control Measures listed on Pages 3, 5, and 6
of Appendix D to the Consent Decree:
• Upper River Des Peres Storage Tunnel serving Lemay Outfalls 064, 066 to 096, 099 to
102, 167, 178 and 180.
• River Des Peres Tributaries Storage Tunnel serving Lemay CSO Outfalls 103, 104, 105,
106, 111, 117 to 128, 130, 131, 134, 136 to 140, 166 and 176.
• Lower & Middle River Des Peres Storage Tunnel serving Lemay CSO Outfalls 008 to
032, 036, 037, 039, 041 to 044, 048, 050, 052, 053, 054, 057, 058, 061, 063, 163, 170 to
173, and 181.
MSD proposes that the Design Criteria for each of these three Control Measures be modified and
clarified by deleting the wording as indicated on the attached pages.
Details
At the ending of the Design Criteria description for each of the listed CSO Control Measures, the
following wording was added: "...to capture flows from Lemay CSO Outfalls [followed by a
listing of each CSO Outfall]." This wording was added to the Consent Decree during the very
last minutes of negotiations (May 27, 2011) as the final change to the Consent Decree before
execution.
MSD believes that this wording could be interpreted as requiring each and every one of the
named CSO Outfalls to be physically connected to the storage tunnel. MSD asserts that this was
not the intent of the LTCP or Consent Decree negotiations, wherein it was recognized that other
means that reflect good engineering practice or provide greater environmental benefit could be
used to meet the Performance Criteria, such as partial or complete sewer separation, elimination
February 4, 2015 ATTACHMENT B Page 2 of 5
of an outfall, or employing emerging technologies such as green infrastructure, if necessary to
meet Performance Criteria. For example, Page 11-6 of the LTCP, discussing the Upper River
Des Peres Storage Tunnel, states that "partial sewer separation may be implemented where
appropriate to reduce the costs for consolidation piping, as determined during final design.
Partial sewer separation may be particularly applicable to some of the outlying CSOs such as
Lemay Outfalls 102 and 167." Similar language appears in the LTCP for the other tunnels
indicating that control techniques could be considered and employed other than physically
routing and connecting all outfalls, especially remote ones, to the tunnels.
MSD is not requesting a revision of the Performance Criteria. Based on the information and
analysis to date, MSD plans to meet the Performance Criteria for the CSO Control Measures for
which it is requesting design modifications. However, MSD does not believe it to be productive
to request a modification to the Consent Decree every time that a different yet acceptable control
technique (i.e., other than capture) is selected as new information is developed during final
design, as long as the Performance Criteria and Critical Milestones are achieved. Therefore,
MSD requests that the indicated wording be removed from the Design Criteria, or modified so as
to allow for other design methods that reflect good engineering practice to be used to meet the
specified Performance Criteria.
February 4, 2015 ATTACHMENT B
Page 3 of 5
Case: 4:07-cv-01120-CEJ Doc. #: 159-4 Filed: 04/27/12 Page; 3 of 9 PegelD I:1617
Appendix D
CSO Control Measures, Design Criteria, Performance Criteria, and Critical Milestones
CSO Control Measures — Upper River Des Peres
Upper River Des
Peres Storage
Tunnel serving
lemay Oulfalls
064, 066 to 096,
099 to 102,16'7,
178 and 180
Description
Deep storage
tunnel,near-
surface facilities,
pump station,
sewer separation
and coauolida-
tinn sewers
[resign Criteria
Provide storage volume of
30 million gallons in der
tunnel system tereapavertlevot
fitertemareeeetitfells
iriFY� L�`iiTviv, '� av very
Porton-Pancr3
Cntcrl;n
When inootporated
with other River Des
Peres CSO controls,
reduce overflows to
4 events or less, and
94 million gallons of
untreated overflow
volume in the typical
vetat
Critical Milestones
• Bid Year— 2028
• Achievement of Full
Operation— 06f30/2034
Upper River Des Peres CSO Controls
Modifications proposed in this request
3
February 4, 2015 ATTACHMENT B
Page 4 of 5
Case: 4:07.ev-01120-CEJ Doc. #: 159-4 Flied: 0427112 Page: 5 of 9 Page#D #: 1619
Appendix D
CSO Control Measures, Design Criteria, Performance Criteria, and Critical Milestones
CSO C duel
Measure
lest rlptiari Design
Purim rti
Criteria
Critical Milestones
River Des 1•eres
Tributaries
Storage Tunnel
serving lemay
CSO Walls 103,
104, 105, 106,
111,117 to 128,
130, 131, 134, 136
to 140, 166 and
176
Storage /
conveyance
tunnel, near -
surface facilities,
pump station,
sower separation
and
consolidation
sewers
Conveyance tunnel with
storage volume of 28 million
gallons tz .:
When incorporated
with other River Des
Peres CSO controls,
reduce overflows to
4 events or less io
River Des Peres tnain
chrome! in the typical
• Bid Year - 2024
• Achievement of Full
Operation - 06/30/2030
River Des Peres Tributaries CSO Controls
Modifications proposed in this request
5
February 4, 2015 ATTACHMENT B
Page 5 of 5
Case: 4:07-cv-01120-CEJ Doc. #: 159-4 Filed: 04/27/12 Page: 6 of 9 PagelD #: 1620
Appendix D
CSO Control Measures, Design Criteria, Performance Criteria, and Critical Milestones
CSO Control Measures — Lower & Middle River Des Peres
CSO Cor trol
M e: s l.i re
De 51.Iuupt i on
Sewer
to all
D�.si 'n Criteria Gt31Bti
MSD's Rules and Regulations
and Engineering Design
Draiasa�e Facilities
Perip nit an ce Ctxli
- -
EE°F
ai Milestones
• vement of lulln _ 01101124
Operatio
on 131imineti of
may t ion
Lemay CSO
Outfal1062
Elimination
Sewer separation
to allow
elimination of
Lemay CSO
Outfall 062
MSD's Rules and Regulations
and Engineering Design
Requirements for Sanitary
Sewet and Stoimwater
Drainage Facilities
Elimination of Lemay
CS Outfe11062
• Achievement droll
Operation- 12/3112015
Treatment reduce
17nit at4anseg'
- �
In -sewer Storage
ipso of
Laney CSO
Outtalk 463
Enhanced
Rate
Clarification
fealty
100 MOD capacity providing
equivalent of primary
clarification, solidsffloatables
disposal, and disinfection
When incorporated
with other River Des
O
Peres ve controls,CSO
overflows to
e
4 events or less in the
typical rap).
Comply with
applicable Missouri
Operating Permit.
• Bid Year - 2027
• Achievement of mall
Operation - 1 213 1 /243p
1
j.,il$ i1,le or
mov
system to allow
flow storage in
horseshoe sewers
Provide 25 million gallons When
i ,within
ecisti
CSO Outfall 063 _ Lemay
incorporated
with
res CSO controls,
own 10
• Achievement of Full
Operation -=1213112030
4 events or tress
t feel )
lower Middle
Raver Des Per
Storage Tunnel
serving Lein"
CSO Outfans 008
to 032, 036, 037,
039, 041 to 044,
048, 050, 052,
053, 054, 057,
058, 061, 063,
163,170 to 173,
and 181
Deep a
tunnel, near-
surface facilities,
1p station,
sewer separation
sad sePma
,hop sewers
°—�
at least 23 , IF
When incorporated
with other River Des
Peres CSO controls,
induce overflows to
4 events or less in the
typical al and
untreated overflow
volume to the River
l pares of
1,412 million gallons
from the Lower &
Middle River Des
Peres Storage Tumael
and the River Des
PereesTributaries
Storage Tunnel
combined
• Bid Year -- 2021
• Achievement of mail
Operation -1213112030
storage volume of
eon ens an
turmei sY
fi,...� L. JrO1 f1 0 lla
, . ,
, , ,
, ,
Iffelirrterfnwrilt1
Modifications per Doc. #: 161 Filed: 07/05/13 Page: 3 of 9
Modifications proposed in Attachment A
Modifications proposed in this request
6