NC0028975_Report (2T 0118 response)_20210707

HIGH COUNTRY
ENGINEERING
July 7, 2021
NCDEQ/DWR/NPDES
Compliance and Expedited Permitting Unit
1617 Mail Service Center
Raleigh, NC 27699-1617
RE: City of Saluda, NC
Response to State regarding the sewer extension moratorium
In accordance with 15A NCAC 02t .0118 (1)
Dear Agency Partners,
The State issued a moratorium letter to City of Saluda on October 21, 2019, citing the annual running
average flowrate at the WWTP discharge meter for the period August 2018 through July 2019 exceeded
80% of the permitted capacity, triggering rule .0118 (1) of the 15A NCAC 02T rules.
The letter and rule .0118 (1) explain "the permittee must submit an approvable engineering
evaluation of their future wastewater treatment, utilization, and disposal needs. This evaluation must
outline specific plans for meeting future wastewater treatment, utilization, or disposal needs by either
expansion of the existing system, elimination or reduction of extraneous flows, or water conservation
and must include the source(s) of funding for the improvements."
High Country Engineering worked directly and closely with City staff to develop this document whose
aim is to outline a specific plan and present it in an approvable manner to the State.
CAUSE OF SSOs and INCREASED WASTEWATER FLOWS
1. Population Growth
Saluda's population has been steady since 2010, with a slight decline from 713 in 2010 to 703 in 2020.
In that period, there has been no addition of flow generating facilities such as schools or manufacturing
facilities. Growth does not appear to be the cause of increased wastewater flows.
2. Physical or Mechanical Limitations at WWTP
Operations staff report no physical or mechanical issues at the WWTP that would limit flow through the
plant and cause surcharge (SSOs) in the collection system. An unscheduled review of the facility reveals
a clean, tidy operation without signs of mechanical failure, overflows or operational difficulties. With
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HIGH COUNTRY ENGINEERING, PC
FAX: [phone] E. Chestnut Street, Asheville, NC 28801

City of Saluda Sewer Moratorium Response
the exception of flow violations, DMR data suggest a smoothly operating, compliant facility. Physical or
mechanical issues do not appear to be a contributing factor.
3. Wet Weather
Based on preliminary evaluation of wastewater flow data provided by Mikal Willmer with NCDEQ and
historic rainfall data obtained via the National Climatic Data Center (NCDC), it appears that elevated
wastewater flows occur in conjunction with wet weather; i.e., classic inflow and infiltration (1/1). The
following data plot of monthly average and running annual average wastewater flows helps to show:
• flow spikes respond to large or clustered rain events
• only 3 months in 2018 exceeded 80% of permit capacity
• during the Aug 2018 — July 2019 period, only four months exceeded 80%, but were of sufficient
magnitude to force the running annual average to exceed 80%
• after the Aug 2018 —July 2019 period, there were 14 consecutive months where the running
annual average was below 80% of capacity, corresponding to overall dryer weather
• data plot begins at Jan 2016 with flow declining from an elevated period which suggests past
wet weather response similar to more recent events and that recent events are not the result of
some sudden large-scale failure in the collection system
0.140
0.120
0.100
0.080
0.060
0.040
0.020
0.000
Saluda Sewer Flow vs. Rainfall Jan 2016 through Apr 2021
Rainfall (in) —0—Monthly —0---Running Annual
ADF (mgd) Average (mgd)
SALUDA'S PLAN TO IDENTIFY AND REDUCE I/1
25
20
15
10
5
0
1. Utilize the Sewer Asset Inventory and Assessment (AIA) Grant to map the collection system,
including age, material and size of pipes to the extent possible, collect cursory system condition
data and house this information in a GIS system. This will be a scalable system; any time new
data comes available, it can be added to improve the inventory and the analytical power of the
GIS.
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HIGH COUNTRY ENGINEERING. PC O
111 E. Chestnut Street, Asheville, NC 28801

City of Saluda Sewer Moratorium Response
When adequate data is in the GIS, a priority ranking system will be implemented, allowing an
Asset Management algorithm to perform a criticality ranking of all assets. This provides a
baseline view of the highest priority areas to begin focusing rehabilitation, replacement or
upgrade efforts.
If AIA funds remain available, collection system flow metering may be implemented to provide
much -needed data to rank basins contributing to I/I and prioritize SSES investigation efforts and
repairs. Future investigations in prioritized basins will include combinations of smoke testing,
dye testing and CCTV. Comprehensive I/1 mitigation projects can be scoped using these data
and funding sources can be sought. [NOTE: in the absence of AIA funds, the city may use funds
from the American Rescue Plan for flow metering.]
This approach implements some elements from EPA guidance for Sewer System Evaluation
Studies (SSES) and I/1 reduction.
This phase is funded by the $150,000 AIA grant and is currently under contract with McGill
Associates. The effort is in the very beginning stages.
Schedule and timing for this effort is anticipated to align with the'22/'23 fiscal year. Mapping
the system, collecting system data and building the GIS is a major effort and delivery of the final
work will be a year or more out.
2. Work with High Country Engineering (HCE) to continue to evaluate data, condition assessment
findings, mapping improvements, individual field observations, and implement individual
improvements as identified. Some improvements under consideration are:
a. installing infiltration dishes in vulnerable manholes
b. rehabilitating old, leaky brick manholes
c. making point repairs near stormwater conveyances demonstrating (indirect) wet weather
connectivity.
Schedule and timing for this effort has begun and we anticipate periodic and continued efforts
in this category throughout the'21/'22 fiscal year. We will maintain records of our efforts for
reporting to DEQ.
3. Using data from the AIA and SSES efforts, detailed projects can be scoped and prioritized.
a. Update Capital Improvement Plan to identify I/1 reduction projects, budgets and
implementation schedules.
b. Consider other funding options, such as CWSRF.
c. Saluda is slated to receive $200,000 via the American Rescue Plan. The City intends to
earmark this money for collection system projects to reduce I/1.
Scheduling and timing for this effort will align with results from the AIA and limited SSES. As
such, CIP updates are anticipated to be developed later in the'22/'23 fiscal year with
implementation beginning, dependent on funding availability, as soon as possible after CIP
adoption and likely lapping into the '23/'24 fiscal year and beyond.
TELEPHONE: [phone]
HIGH COUNTRY ENGINEERING, PC
FAX: [phone] E. Chestnut Street, Asheville, NC 28801

City of Saluda Sewer Moratorium Response
With the submittal of this document, the City of Saluda requests the State lift the moratorium on
sewer extensions and connections, allowing time to implement our plan and reduce wet weather
flow.
We appreciate your consideration of our request and your continued assistance with system
management and compliance.
If you have questions regarding this submittal, you are welcomed to call me at [phone] or City
Manager Steve Orr at [phone].
Sincerely,
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James N. (Jay) Johnston, PE
High Country Engineering, PC
Firm No.: C-3347
TELEPHONE: [phone]
HIGH COUNTRY ENGINEERING. PC
FAX: [phone] E. Chestnut Street, Asheville. NC 28801