NC0020591_Wasteload Allocation_19820218

NPDES DOCYNENT SCANNING COVER SHEET
NPDES Permit:
NC0020591
Statesville/Third Creek WWTP
Document Type:
Permit Issuance
Wasteload Allocation
Authorization to Construct (AtC)
Permit Modification
Complete File - Historical
Engineering Alternatives (EAA)
Correspondence
Instream Assessment (67b)
Speculative Limits
Environmental Assessment (EA)
Document Date:
February 18, 1982
Thus document its printed on revLme paper - ignore any
content on the resrerBe esiae

NPDES WASTE LOAD ALLOCATION
Facility Name: �U/Date: e"l JAI
Existing Ef
/✓�00 a 05 9 / �`Z6 .P�
Permit No.: �� Pipe No.: OD/ County:
Proposed
Design Capacity (MGD): ¢ 0 Industrial (% of Flow):
Domestic (% of Flow):
Receiving Stream: ili/✓lf i7,er ' fVag!Z Class: _ Sub -Basin: 0-1 —O%-OG
Reference USGS Quad:
(Please attach) Requestor: J. qk// Regional Office Kk"00129
(Guideline limitations, if applicable, are to be listed on the back of this form.)
Design Temp.: _ Z�4j a ` C 1 i s.C- 3 Drainage Area: 5 :-,, .2 VA, a Avg. Streamflow:
7Q10 : I I c t z (3 1 ('i _ J Winter 7Q10 : 30Q2 :
Location of D.O.minimum (miles below outfall): 4. 7 Slope:. `7�eve:
Velocity (fps) : C7 `i� C, Kl (base e, per day, 200C) : G K2 (base e, per day, 200C)
virrri�`,-+ O fil I 7 Qc4 31J\\
Effluent
Characteristics
Monthly
Average
Comments
p:Ulj�
� one
A
5 ^^
Effluent
Characteristics
Monthly
Average
Comments
'• is t_,
J
4 Y`Ni
7
—
Original Allocation
Revised Allocation Date(s) of Revision(s)
(Please attach previous allocation)
repared By: J'. 'a . a A z ; Reviewed By: ��(/ Date: n

1_
i
a
For Appropriate Dischargers, list Complete Guideline limitations Below
Effluent
Characteristics
Monthly
Average
Maximum Daily
Average
Comments
l
Type of Product Produced Lbs/Day Produced Effluent Guideline Reference

Form #001
WASTE LOAD ALLOCATION APPROVAL FORM
#227
Facility Name: Statesville - Third Creek WWTP
County: Iredell Sub -basin: 3- 7-06
Regional Office: MRO Requestor: S. Abdul-Hagq
Type of Wastewater: Industrial
Domestic %
If industrial, specify type(s) of industry:
Receiving stream: Third Creek Class: C
Other stream(s) affected: Classe
7Q10 flow at point of discharge: 11 cfs (winter - 21 cfc)
30Q2 flow at point of discharge:
Natural stream drainage area at, discharge point: 53.9 mil
Recommended Effluent Limitations
Monthly Avg.
Summer (April 1 thru Oct. 31)
Qw = 4 MGD
BOD5 = 19 mg/1
NH3-N = 11 mg/l
DO = 5 mg/l
TSS = 30 mg/l
Fecal Coli = 1000/100 ml
pH = 6-9 SU
Winter (Nov. 1 to March 31)
Qw = 4 MGD
BOD5 = 30 mg/1
TSS = 30 mg/1
Fecal Coli = 1000/100 ml
pH = 6-9 SU
Summer limits revised due to USGS revision in 7Q10 flow estimate, and
recalculation of runoff, velocity, and depth. BOD5 and NH3-N were
18 mg/l, and 8 mg/l, respectively. See attached explanation.
This allocation is:
/ )/
Recommended and reviewed by:
Head, Techncial Services
for a proposed facility
for a new (existing) facility
a revision of existing limitations
a confirmation of existing limitations
Date: 1 -,
Date:
Reviewed by:
Regional Supervisor S /`/zi ^ � G✓ Date: 9 -r-k Z
Permits Manager Lj.w. % Date: 2
Approved by:
Division Director Dater 112 Apt

p
Explanation of the Changes to the Statesville -Third Creek Model
In arriving at the new allocation for this discharger, four parameters
have been changed in the old Third Creek model: the upstream 7-day 10-year low
flow, the 7-day 10-year low flow runoff, the vel,_-A ty, and the stream depth.
The 1980 estimate by USGS for 7-day 10-year low flow at the discharge point
for the Statesville Third Creek WWTP is 11 cfs. This has been revised from a
former USGS estimate of 14 cfs.
The 7-day 10-year low flow runoff has been revised from 0.0 cfs/stream
mile to 1.76 cfs/mile. The new estimate is based on drainage area along the
stream length, and on the 7Q10 yield calculated from the updated USGS upstream
flow of 11 cfs.
Velocity and depth values in the old model were calculated from regression
equations based on flow which were developed by USGS for their station at the
I-77 bridae over Third Creek. These values were velocity = 1 fps., depth = 0.6 ft.
However, we feel now that velocities calculated from this type of regression
equation are often unrepresentative of flow -through velocities over an extended
stream reach. These regression equations are sometimes based on stations located
at bridges, where the hydraulic conditions differ from those over the major portion
of the stream. For this reason, the velocity in the revised analysis has been
l reestimated, using the regression equation developed by DEM. Depth is calculated
from flow and velocity, using our standard methodology. The new values are
velocity = 0.44 fps., and depth = 1.6 ft.