|
Midland Ave Regional Treatment Facility & Conveyances—Facility Plan, Jan 2003
by Environmental Engineering Associates, LLP
for Onondaga County Department of Water Environment Protection
3. Midland Avenue conveyances/off-line storage
This section provides a brief description, basis of
design flows, and preliminary sizing of the Midland
Avenue conveyances and off-line storage facility.
The Midland Avenue Conveyances will consist of CSO
transmission pipelines of varying sizes, located along
Onondaga Creek in the southern section of the City of
Syracuse. The Midland Avenue Conveyances will collect
overflows from the existing CSOs 039, 042, and 044, up
to the one-year design storm, and all combined sewer
flow from CSOs 043, 052, 060 (includes former Overflow
077), 061,067 (see Newell Street CSO discussions in
Section 2.4), 076 [to be permanently closed] and
convey these flows to the Midland Avenue RTF, to be
located near Oxford Street. The Midland Avenue
Conveyances and proposed 2.5 million gallon (MG)
off-line, underground storage tank (to be located
northwest of the intersection of Midland Avenue and
West Castle Street) will also provide flow storage and
attenuate the peak flow to the Midland Avenue RTF. At
CSO locations 039, 042, and 044, the existing
regulator structures will be modified to direct
overflows up to the one-year design storm event to the
new Conveyance pipelines and, as appropriate, the
off-line storage facilities. For CSO locations 043,
052, 060 (includes former Overflow 077), 061, 067, and
076, the existing regulator structures will be
permanently closed and all flows will be directed to
the Conveyances pipelines and, as appropriate, the
off-line storage facility.
The Midland Avenue Conveyances/Off-Line Storage
Facility will include the following components:
from Tallman Street to the Midland Avenue RTF, which
will collect and convey combined sewer flow (up to the
one-year design storm event) from CSO 039;
from West Newell Street to the Midland Avenue RTF,
which will convey combined sewer flow (up to the
one-year design storm event) from CSO 044 and all
combined sewer flows from CSOs 043, 060 (includes
former Overflow 077), 061, 067, and 076.
which will convey combined sewer flow (up to the
one-year design storm event) from CSO 042 across
Onondaga Creek to the RTF; and
siphon (to be determined during design), which will
convey all combined sewer flow from CSO 052 across
Onondaga Creek to the Midland Avenue Conveyances and
RTF.
Figure 3-1 presents the conceptual plan layout for the Midland Avenue Conveyances and Off-Line Storage Facility.
This conceptual plan will be further developed during final design.
In addition to the CSO transmission pipelines and
off-line storage facility, a connection between the
existing Main Interceptor Sewer (MIS) and the Midland
Avenue RTF must be provided to allow a portion of the
flows in the filled MIS upstream of the RTF to
discharge into the RTF. This relief of MIS flows will
provide for downstream conveyance capacity in the MIS
for the RTF underflow (equal to five percent of the
RTF influent pumping/treatment rate).
As noted in
Section 1.3,
overflows from CSOs 038, 040,
041, 045, 046A, 046B, 047, 048, 050, 051, 053, and 054
will not be connected to the Midland Avenue
Conveyances or contribute flow to the Midland Avenue
RTF, as existing combined sewers in these areas will
be separated. Under this sewer separation program, it
is generally anticipated that new sanitary sewers will
be constructed in these drainage basins and existing
combined sewers will be converted to storm sewers,
with the existing CSO outfall converted to a storm
sewer outfall. Alternatively, sub-basin storm only
discharges may be directed to an adjacent sub-basin to
permit the closure of the existing CSO outfall. This
sewer separation program will prevent future CSO
discharges from these drainage areas.
As described previously in
Section 1.5,
the ACJ established two phases for construction of the Midland
Avenue RTF and Conveyances project. Phase One included
construction of the Conveyances with a construction
commencement date of May 1, 1999 and a construction
completion/begin operation date of May 1, 2004. Phase
Two included construction of the RTF with a
construction commencement date of May 1, 2004 and a
construction completion/begin operation date (major
milestone) of May 1, 2007.
In order to comply with the ACJ CSO Construction
Milestone Completion Schedule outlined above and to
better address construction impact issues associated
with constructing the RTF following construction of
the Conveyances in accordance with the ACJ, the
County, in conjunction with NYSDEC, requested
modification to the construction sequencing of the
project to initiate the RTF project prior to
completion of the Conveyances project.
A more thorough discussion of this revised project sequencing is presented in
Section 5.
Based on the CSO conveyance and RTF capacity
determinations resulting from the RTF Hydraulic
Evaluations described in Section 2.2, the Midland
Avenue CSO Conveyances have been sized to accommodate
additional pipeline storage and conveyance capacity
for the one-year design storm event. Specifically, the
design flow rates for the Midland Avenue Conveyances
have been developed based on the following:
-
Transmission to the Midland Avenue RTF of the peak
discharge from the CSOs to remain in the system upon
completion of the Project (i.e., CSOs 039, 042, and
044) up to the one-year design storm event;
-
Necessary service area capture component to result
in a minimum 85% capture of the total system-wide
overflow volume; and
-
Transmission to the Midland Avenue RTF of
additional flows above the one-year design storm event
for the six CSOs scheduled to be closed upon
completion of the Project (i.e., CSOs 043, 052, 060
(includes former Overflow 077), 061, 067, and 076), as
discussed in Sections 2.2 and 2.3.
Table 3-1 presents the design flow rates and required
sizing for each segment of the proposed Midland Avenue
Conveyances.
| TABLE 3-1. CONVEYANCE DESIGN FLOW RATES / SIZING |
|
CSO transmission conduits (CSO connected)
|
Diameter (inches)
|
Approx length (ft)
|
Peak flow (cfs)
|
|
Midland Transmission Conduits
|
|
|
|
|
W. Newell Street (CSO 067)/W. Brighton Avenue (CSO 076)
|
36
|
1,020
|
26
|
|
W. Brighton Avenue (CSO 076)/Elmhurst Avenue (CSO 052)
|
54
|
600
|
42
|
|
Elmhurst Avenue (CSO 052)/W. Colvin (CSO 060)
|
66
|
850
|
138
|
|
W. Colvin (CSO 060)/Kirk Avenue
|
120
|
1,850
|
304
|
|
Kirk Avenue/South Avenue (CSO 044)
|
144
|
1,525
|
303
|
|
South Avenue (CSO 044)/Midland Avenue (CSO 043)
|
144
|
1,360
|
430
|
|
Midland Avenue (CSO 043)/Midland RTF
|
144
|
295
|
511
|
|
|
|
|
|
|
Tallman Transmission Conduits (039)
|
|
|
|
|
Tallman Street East
|
54
|
128
|
255
|
|
Tallman Street/Midland RTF
|
84
|
886
|
255
|
|
|
|
|
|
|
Bellevue Avenue Transmission Conduits (042)
|
|
|
|
|
Midland Avenue/Midland RTF
|
66
|
200
|
183
|
|
|
|
|
|
|
Elmhurst Avenue Transmission Conduits (052)
|
|
|
|
|
Elmhurst Avenue (CSO 052)/Midland Trans. Conduits
|
66
|
180
|
100
|
|
|
|
|
|
|
Connection Conduits
|
|
|
|
|
Midland Avenue East (CSO 043)
|
72
|
35
|
225
|
|
West Castle/South Avenue (CSO 044)
|
48
|
50
|
65
|
|
West Colvin (CSO 060 and CSO 077)
|
60
|
40
|
185
|
|
Crehange/Onondaga (CSO 061)
|
12
|
25
|
8
|
|
Brighton/Midland Avenue (CSO 076)
|
54
|
0
|
40
|
|
MIS TAP
|
48
|
40
|
33
|
As noted in
Appendix E, Midland RTF Size Evaluations,
a total of 6.7 MG of in-line/off-line
storage (2.5 MG additional in-line/off-line storage
plus 4.2 MG storage in Midland Avenue Conveyances) is
necessary to reduce the peak influent flow rate of the
RTF to 330 cfs to achieve ACJ compliance for the
Midland Avenue service area. During preliminary
planning for the additional 2.5 MG in-line/off-line
storage, a parallel 12-foot diameter pipeline, 900
feet in length (0.8 MG storage) plus a 1.7 MG off-line
underground storage tank were considered as options to
achieve the total required storage of 2.5 MG. Further
review of the available land area for locating the
additional 2.5 MG of upstream storage (northwest
intersection of Midland Avenue and West Castle Street
on the east side of Onondaga Creek) revealed that
construction of the parallel 12-foot diameter pipeline
would potentially interfere with the stability of the
existing Main Interceptor Sewer (MIS) that parallels
the eastern edge of Onondaga Creek in close proximity
to the proposed parallel pipeline. Therefore, it has
been determined that a single, 2.5 MG underground
storage tank in the Midland Avenue/West Castle Street
location provides the most practical and
cost-effective upstream, off-line storage option for
use in conjunction with 330 cfs RTF.
Figure 3-1 depicts the conceptual plan location for the 2.5 MG upstream, off-line storage facility.
Figure 3-2
and
Figure 3-3
depict a conceptual plan and section for the 2.5 MG off-line storage facility.
|
Susan Miller, Project Deputy Director
Onondaga County Dept of Water Environment Protection