410006_Sludge Survey Extension Request_20200911

NC Department of
Environmental Quality
Received
SEP 11 2020
1
k, Winston-Salem
Regional Office
September 3, 2020
Rebecca Chandler
Environmental Specialist
DENR- Division of Water Quality
Winston-Salem Regional Office
450 Hanes Mill Rd, Suite 300
Winston-Salem, NC 27105
Dear Ms. Chandler,
Bruce Humble
Humble Stock Farm
Facility # 41-16
6653 Smithwood Road
Liberty, NC 27298
I would like to request an exemption from the annual sludge survey on my second stage lagoon for 5
years. I have attached the copy of my Lagoon Sludge Survey Form. Millie Langley, with Guilford SWCD
and Michael Shepherd with the Div. of Soil & Water assisted me with the sludge survey. As you can see,
the amount of sludge is quite low. And has remained low since the lagoon was built in 1991.
Thank you for your consideration of this matter.
Sincerely,
Bruce Humble
Humble Stock Farm

Appendix 1. Lagoon Sludge Survey Form Revised August2008
A. Farm Permit or DWQ Identification Number 41-16
B. Lagoon Identification Lagoon 2
C. Person(s) Taking Measurements Michael Shepherd
D. Date of Measurements 9-2-2020
E. Methods/Devices Used for Measurement of:
a. Distance from the lagoon liquid surface to the top of the sludge layer:
DSWC Sludge Boat
b. Distance from the lagoon liquid surface to the bottom (soil) of the lagoon:
c. Thickness
a direct measurement with "core sampler":
F. Lagoon Surface Area (using dimensions at inside top of bank): __L_(acres)
(Draw a sketch of the lagoon on a separate sheet, list dimensions, and calculate surface area. The lagoon may
have been built different than designed, so measurements should be made.)
G. Estimate number of sampling points:
a. Less than 1.33 acres: Use 8 points
b. If more than 1.33 acres, acres x 6 = with maximum of 24.
(Using sketch and dimensions, develop a uniform grid that has the same number of intersections as the
estimated number of sampling points needed. Number the intersection points on the lagoon grid so that
data recorded at each can be easily matched.)
H. Conduct sludge survey and record data on "Sludge Survey Data Sheet" (Appendix 2). Also, at the location of
the pump intake, take measurement of distance from liquid surface to top of sludge layer and record it
on the Data Sheet past row); this must be at least 2.5 it when irrigating.
I. At the time of the sludge survey, also measure the distance from the Maximum Liquid Level to the Present
Liquid Level (measure at the lagoon gauge pole): 2
J. Determine the distance from the top of bank to the Maximum Liquid Level 1.5
(use lagoon management plan or other lagoon records)
K. Determine the distance from the Maximum Liquid Level to the Minimum Liquid Level 2.2
(use lagoon management plan or other lagoon records)
L. Calculate the distance from the present liquid surface level to the Minimum Liquid Level 0.2
(Item K minus Item I, assuming the present liquid level is below the Maximum Liquid Level):
M. Record from the Sludge Survey Data Sheet the distance from the present liquid surface level to the lagoon
bottom (average for all the measurement points): 8.5
N. Record from the Sludge Survey Data Sheet the distance from the present liquid surface level to the top of the
sludge layer (average for all the measurement points): 7
O. Record from the Sludge Survey Data Sheet the average thickness of the sludge layer: 1.5
P. Calculate the thickness of the existing Liquid Treatment Zone (Item N minus Item L): 6.8
Q. If Item O is greater than Item P, proceed to the Worksheet for Sludge Volume and Treatment Volume.
If Item O is equal to. or less than Item P, you do not have to determine volumes.
Completed by: Michael Shepherd Date: 9-2-2020
Print Name Signature

Appendix 2. Sludge Survey Data Sheet* Revised August 2008
Lagoon Identification: Lagoon # 2
Completed by: Michael Shepherd Wk;cWr S4aA4Z Date: 9-2-2020
Print Name Signature
(A)
Grid
Point
(B)
Distance from liquid
surface to top of sludge
(C)
Distance from liquid surface
to lagoon bottom (soil)
(C) minus (B)
Thickness of sludge layer
No.
Ft. & in.
Ft. tenths
Ft. & in.
Ft. tenths
Ft. & in.
Ft. tenths
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Number of points with
readings 842
X
X
Average
Of
points
7
g,5
1.5
At
pump
intake
X
X
XFX
*All Grid Points and corresponding sludge laver thicknesses must be shown on a sketch attached
to this Sludge Survey Data Sheet. See Appendix 4 for conversion from inches to tenths of a foot.

Appendix 3. Worksheet for sludge volume and treatment volume Revised August 2008
The average thickness of the sludge layer and the thickness of the existing liquid (sludge -free) treatment
zone (are determined from information on the Lagoon Sludge. Survey Form (Items O and P, respectively).
In this example, the average sludge layer thickness is 2.5 feet and the existing liquid treatment zone is 3.5
feet. If the lagoon has a designed sludge storage volume, see notes at end of the worksheet. The
dimensions of the lagoon as measured and the side slope are needed for calculations of sludge volume
and of total treatment volume. If the lagoon is a standard geometric shape, the sludge volume and
treatment volume in the lagoon can be estimated by using standard equations. For approximate volumes
of rectangular lagoons with constant side slope, calculate length and width at the midpoint of the layer,
and multiply by layer thickness to calculate layer volume, as shown in the example. For irregular shapes,
convert the total surface area to a square or rectangular shape. For exact volumes for lagoons with
constant side slope, the "Prismoidal Equations" may be used.
Example
Your lagoon
1.
Average Sludge Layer Thickness (T)
2.5 ft.
1.5
2.
Depth of lagoon from top of bank
to bottom soil surface (D)
11 ft.
12
3.
Slope = horizontal/vertical side slope (S)
3
2
4.
Length at top inside bank (L)
457 ft.
308
5.
Width at top inside bank (W)
229 ft.
140
6.
Length at midpoint of sludge layer
L. = L — 2 S (D- (T/2))
398.5 ft.
263
7.
Width at midpoint of sludge layer
Wm = W — 2 S (D — (T/2))
170.5 f1.
95
8.
Volume of sludge (Vs):
Vs = Lm Wm T
169,860 if
37,478
9. Volume in gallons:
Vag =V * 7.5 gal./W. 1,273,950 gal. 281,081
10. Thickness of existing liquid trot. Zone (Y) 3.5 ft. 6.8
11. Thickness of total treatment zone (Z) 6.0 ft. 8.3
Z=T+Y
(Appendix 3 continued on next page)

Revised August 2008
Appendix 3. Worksheet for sludge volume and treatment volume (continued)
12. Length at midpoint of total trot. zone 409 ft. 276.6
Lz = L — 2(S) (D — (Z/2)
13. Width at midpoint of total tint. zone 181 ft. 108.6
Wz = W — 2(S) (D — (Z/2)
14. Volume of total treatment zone (Vz) _444,174 ft3_ 249,322
Vz=LzWzZ
15. Ratio (R) of sludge layer volume to total
Treatment volume
R=VsNz 0.38 0.15
If the ratio exceeds 0.50, than a sludge Plan of Action may be required. Check with
DWQ for information on filing the Plan of Action.
Note: If the lagoon has a designed sludge storage volume (DSSV), subtract that volume from
both the volume of sludge (Vs) (Item 8) and from the volume of total treatment zone (Vz) (Item
14), and take the ratio:
R = (Vs — DSSV) / (Vz — DSSV)
Example: If DSSV = 85,000 ft, then R = (169,860 — 85,000) / (444,174 — 85,000)
R = 84,860 / 359,174 = 0.24
Appendix 4. Conversion table from inches to tenths of a foot.
Inches
Tenths of
foot
Inches
Tenths of
foot
1
0.1
7
0.6
2
0.2
8
0.7
3
0.2
9
0.7
4
0.3
10
0.8
5
0.4
111
10.9
6
0.5