WQ0045579_Correspondence_20240712

Baker, Caroline D
From: Crisp, Dale
Sent: Friday, July 12, 2024 12:10 PM
To: 'Kendall Godfrey'
Cc: Lentz, Zac; Montebello, Michael J; '[e-mail]'; 'Jarrett, Jason';
'Marshall, Jason'; Coco, Nick A; Nevills, Matthew; Pitner, Andrew
Subject: Charlotte Water - Strollaway Road LPSS (WQ0045579) permit application package
A review of the application and supporting documents for the subject application has been completed in accordance
with 15A NCAC 02T .0107. Please provide the additional or revised information for the following comments, in order
for the Division to complete the review:
1. The permit application for this LPSS project requests approval of 1,140 gpd based on the 190 gpd /dwelling unit
/ lot @ 6 residential lots. The project includes an extension of 362 linear feet of 3-inch pressure sewer main to
be owned and maintained by Charlotte Water in the public right-of-way portion of Strollaway Road. After
reviewing supplemental documents, site map, engineering plans and specs included in this application package,
please explain how the six (6) residential lots, which all appear to be located at the end of the Strollaway Road
cul-de-sac and accessed only by a private driveway / road will be served. Specifically, will there be individual
pressure service laterals to each of the six (6) residences in the future or will there be a privately owned and
maintain pressure sewer collection main? A private collection pressure main will require permitting by the
Division. If individual pressure service laterals from each of the six (6) lots is proposed, please provide an
explanation and example of how these six pressure service taps can be located in such a limited area at the end
of the private driveway on the cul-de-sac along with the other existing and proposed utilities.
2. On the engineering plan sheet 3 of 4 at approximately Sta 3+00 to Sta 3+62 the proposed 3-inch pressure sewer
main parallels a proposed 2-inch water main around the Strollaway Road cul-de-sac. Please indicate on the plans
that a 10 feet horizontal separation will be provided between these proposed mains.
3. Appendix #3 in the Customer Information Packet and also on a table located on sheet 3 of 4 of the engineering
plans lists the proposed pump rates for each of the 6 simplex pumps which range from a minimum of 25.4 GPM
to a maximum of 30.1 GPM. None of the proposed pump rates achieve a minimum flowrate required to achieve
a scour velocity of 2 fps in the proposed 3-inch pressure main. Please revise to meet the Division's Minimum
Design Criteria for Sewer Pump Stations and Force Mains.
4. The project calculations summary supporting documents indicate the design calculations for the existing
pressure sewer modeling utilized a C factor of 140 in the design calculations. While an "initial installation" C
factor of 140 is acceptable, an "end of service" C factor of 120 is also required for evaluation per the Division's
Minimum Design Criteria for Sewer Pump Stations and Force Mains. Please provide calculations showing
performance of the design of the proposed pressure sewer with a C factor of 120 utilized in the modeling
calculations.
A response to the above comments is considered required in order to proceed with the review of the application and
issuance of the permit. If a complete response is not received within 30 days, the application and supporting documents
will be returned to you in accordance with 15A NCAC 02T.0107(e)(2).
Please feel free to provide digital copies of these revised documents and supporting information to me via email along
with hardcopies via mail.
Please let me know if you have any questions. Dale

H. Dale Crisp, PE
Environmental Engineer II
Municipal Permitting Unit
NC Division of Water Resources
919-707-3603