WQ0039910_Narrative_20220525

Town of Pittsboro
Wastewater Transmission System Improvements
Original Narrative
The proposed project includes an influent headworks for the preliminary treatment of raw
wastewater entering the Pittsboro Wastewater Treatment Plant site. The headworks
consists of dual mechanical bar screens with screenings compactors, a manual bypass bar
screen, dual grit removal systems, Parshall Flume for influent metering and an odor
control system.
Following preliminary treatment, the raw wastewater flows into the Transfer Pump
Station. This station includes three (3) transfer pumps (2 duty and 1 standby) that will
transmit wastewater to the Sanford Big Buffalo Wastewater Treatment Plant. This station
also includes two (2) equalization pumps (1 duty and 1 standby) that will transmit excess
flow to up to five (5) equalization tanks at the plant site. Equalization Tanks 1 and 2 are
existing and will be reused. Equalization Tanks 3 & 4 are being created through the
conversion of the existing aeration/clarifier basins for equalization storage. Equalization
Tank 5 is being created through the conversion of the existing sludge holding tanks for
equalization storage. Each equalization tank will include a means of aeration/mixing and
be capable of returning stored wastewater to the Transfer Pump Station for transmission
to Sanford.
The proposed force main starts from Pittsboro Wastewater Treatment Plant and continues
south within Town owned property/easements, crosses Pittsboro/Moncur Rd, then
continues south along US 151501 inside the existing road R/W. After crossing into Lee
County, the alignment shifts due west along Brown Road and other Town owned
easements, crosses the railroad tracks, turns east and crosses Hawkins Ave, continues
within a utility easement where it ties into Sanford's gravity sewer system immediately
upstream of Sanford's Little Buffalo Lift Station.
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Summary of Proiect Changes (since permit was approved 7/15/2021):
Contract 1 (Headworks/Pump Station
No changes were made to Contract 1.
Contract 2 (Force Main):
Just south of the RR crossing, at approximately STA 676+50, the FM turns east, parallels
the RR on the south side, crosses a stream via HDD, and then crosses Hawkins Ave via
dry bore and jack. It then continues along Lee Brick's paved driveway, crossing their
concrete laydown area, where it discharges into a 5' diameter manhole. From there, flow
is conveyed 35 linear feet through a 24" gravity sewer main to an 8' diameter manhole
located approximately 80 feet upstream of Sanford's Little Buffalo Lift Station. The
remainder of the project corridor north of the railroad remains virtually unchanged.
The original FM alignment turned west and ran west/southwest after the RR crossing
until it reached Sanford's existing force mains. After crossing Sanford's force mains, it
turned west and ran parallel with the existing force mains, crossing Iron Furnace Rd via
bore & jack, and then tied into an existing 42" force main at the Big Buffalo WWTP.
Figure 1 and Figure 2, attached, show the current alignment as well as the former FM
alignment and the realignment to LBLS, respectively.
Quick summary of design changes:
• The FM was shortened by approximately 5,700 LF
• FM discharge elevation
0 original FM alignment tied into existing piping at elevation 254.8'
o new alignment discharge elevation at manhole (STA 698+59) is 258.94'
• Stream crossings (reduced total stream crossings by 1):
o removed HDD under Perry Creek and unnamed stream (total LF removed =
684)
o added 409 LF HDD under stream/wetland just west of Hawkins Ave.
• Bore & Jack:
o removed 53 LF B&J under Iron Furnace Rd
o added 166 LF B&J under Hawkins Ave.
• Air release valves (reduced total number of ARVs by 4):
o removed 6 ARVs
o added 2 ARVs
• Added 2 manholes (5' & 8' diameter) and 35 LF of 24" gravity sewer
Project Timeline:
Both Contract 1 & 2 are expected to begin construction in early 2023. Contract 2 has a
contract time of 480 days and Contract 1 has a contract time of 660 days. Construction of
both Contracts is anticipated to be complete in winter 2024. Upgrades to the LBLS are
expected to be complete by the summer of 2024; therefore, the LBLS is not expected to
see flows from Pittsboro until after upgrades are complete.
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