WQ0045579_Cover Letter / Narrative_20240701

State of North Carolina
Department of Environment,
Health and Natural Resources
Division of Environmental Management
James B. Hunt, Jr., Governor
Jonathan B. Howes, Secretary
A. Preston Howard, Jr., P.E., Director
February 13, 1995
Barry M. Gullet, P.E., Deputy Director
Charlotte -Mecklenburg Utility Department
5100 Brookshire Boulevard
Charlotte, North Carolina 28216
RE: Charlotte -Mecklenburg Utility Department
Reduction in Wastewater Flows
Mecklenburg County
Dear Mr. Gullet:
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On July 20, 1994, the Division received your wastewater flow reduction request and support
documentation concerning wastewater flows associated with the entire Charlotte -Mecklenburg Utility
Department service area. Your letter requested the Division allow the reduction of wastewater flows from
250 GPD per dwelling unit which was previously approved in accordance with North Carolina
Administrative Code, to 190 GPD per dwelling unit for single family residential areas and 135 GPD per
dwelling. unit for multi -family residential. areas- In support of your request, documentation was provided
from the existing Irwin, Sugar, and McAlpine Creek wastewater treatment plant service areas.
The documentation provided in support of the flow reduction request was compiled by Camp
Dresser & McKee starting in late 1990 and is currently ongoing. Data submitted to the Division was not in
strict accordance with 15A NCAC .0219(1)(3), however, in view of the submitted documentation,
adequate justification was provided in support of the wastewater flow reduction request The work
completed by Camp Dresser & McKee consisted of tracking base wastewater flows, groundwater
infiltration, and rainfall -dependent infiltration/inflow for the Irwin, Sugar, and McAlpine Creek
wastewater treatment plant service areas. Data was collected from 106 flow monitors (both permanent and
temporary) and 14 rain gauges during November and December 1991 located along major sewer trunklines
within the study area. Existing dry -weather flows were developed for each of the three (3) wastewater
treatment plant service areas which included groundwater infiltration. The service area dry -weather low
estimates were further broken-down into thirteen (13) drainage basins. These revised dry -weather flow
estimates were compared to land -use based flow estimates developed using existing land data for 446
Origination and Destination (O&D) planning zones as provided by the City of Charlotte's Department of
Transportation. From this comparison the revised wastewater flows were developed. Although these
numbers were developed for Irwin, Sugar, and McAlpine Creek service areas, the results would also be
applicable to both the Mallard Creek and McDowell Creek wastewater treatment plant service areas.
In view of the information submitted, the Division of Environmental Management will allow the
use of 190 GPD per dwelling unit for single family residential areas and 135 GPD per dwelling unit for
multi -family residential areas on all applicable non -discharge permit applications for future wastewater
collection extensions which will be made tributary to all five (5) Charlotte -Mecklenburg Utility Department
wastewater treatment facilities. This consideration applies to any applicable future projects submitted to
this Division as well as any projects which are presently under review. Wastewater flows presently
tributary to the wastewater treatment facilities can be adjusted upon negotiations between the Charlotte -
Mecklenburg Utility Department and the Division's Mooresville Regional Office.
P.O. Box 29535, Raleigh, North Carolina 27626-0535 Telephone [phone] FAX [phone]
An Equal Opportunity Affirmative Action Employer 50 % recycled/ 10% post -consumer paper

Page 2
Charlctte-Mecklenburg Utility Department
February 13, 1995
The Division does have concerns regarding the proposed sewage flow rates with respect to
infiltration and inflow. Although the 190 GPD per dwelling unit for single family residential areas and
135 GPD per dwelling unit for multi -family residential areas are justifiable flow rates, the Charlotte -
Mecklenburg Utility Department has in essence reduced the safety factor typically associated with
infiltration and inflow. The flow rate established by the Division does allow for some infiltration and
inflow. The Division is of the opinion that proper wastewater collection system management is more
effectively and efficiently accomplished by the entity that is accountable for ensuring overall compliance
with all aspects of wastewater collection, treatment, and disposal requirements. In this view, we look
forward to continued progress by the Charlotte -Mecklenburg Utility Department to fully assume the
wastewater collection permitting program.
If you have any questions or comments regarding this matter, please contact Mr. Michael D. Allen
at [phone]
Sincerely,
KQ�X-1
�A. Preston Howard, Jr., P.E.
cc: Mooresville Regional Office, Water Quality
State Engineering Review Group