WQ0004972_Staff Report_20201210

DocuSign Envelope ID:18280350-DD97-4275-B92A-B8E3A7EA3541
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State of North Carolina
Division of Water Resources
Water Quality Regional Operations Section
Staff Report
December 9, 2020
To: DWR Central Office — WQ, Non -Discharge Unit Application No.: WQ0004972
Attn: Poonam Giri Facility name: Forest Lake Preserve, Wastewater Irrigation System
From: Patrick Mitchell
Winston-Salem Regional Office
Note: This form has been adapted from the non -discharge facility staff report to document the review of both non -discharge and NPDES permit applications and/or renewals. Please complete all sections as they are applicable.
I. GENERAL AND SITE VISIT INFORMATION
1. Was a site visit conducted? Yes or ® No
a. Date of most recent site visit: October 21, 2020
b. Site visit conducted by: Justin Henderson
c. Inspection report attached? ❑ Yes or ® No
d. Driving directions: See file.
II. EXISTING FACILITIES: MODIFICATION AND RENEWAL APPLICATIONS
1. Are there appropriately certified Operators in Charge (ORCs) for the facility? ® Yes ❑ No ❑ N/A
2. Are the design, maintenance and operation of the treatment facilities adequate for the type of waste and disposal
system? ® Yes or n No
3. Are the site conditions (e.g., soils, topography, depth to water table, etc) maintained appropriately and adequately
assimilating the waste? ® Yes or ❑ No
Note: No issues noted in inspection report.
4. Has the site changed in any way that may affect the permit (e.g., drainage added, new wells inside the compliance
boundary, new development, etc.)? n Yes or ® No
Note: No issues noted in inspection report.
5. Is the residuals management plan adequate? ❑ Yes or ® No
If no, please explain: A residuals management plan needs to be created for this facility.
6. Are the existing application rates (e.g., hydraulic, nutrient) still acceptable? ® Yes or ❑ No
Note: No issues noted in inspection report.
7. Is the existing groundwater monitoring program adequate? ® Yes ❑ No ❑ N/A
Note: No issues noted in inspection report.
8. Are there any setback conflicts for existing treatment, storage and disposal sites? ❑ Yes or ® No
Note: No issues noted in inspection report.
9. Is the description of the facilities as written in the existing permit correct? ❑ Yes or ® No
If no, please explain: Acrege listed in description is not correct. See IV. Additional Regional Staff Review Items.
10. Were monitoring wells properly constructed and located? ® Yes ❑ No ❑ N/A
Note: No issues noted in inspection report.
11. Are the monitoring well coordinates correct in BIMS? ® Yes n No ❑ N/A
12. Has a review of all self -monitoring data been conducted (e.g., DMR, NDMR, NDAR, GW)? ® Yes or 111 No
13. Are there any permit changes needed in order to address ongoing BIMS violations? ❑ Yes or ® No
FORM: WQROSSR 04-14 Page 1 of 3

DocuSign Envelope ID: 18280350-DD97-4275-B92A-B8E3A7EA3541
14. Check all that apply:
❑ No compliance issues n Current enforcement action(s) ❑ Currently under JOC
Notice(s) of violation n Currently under SOC ❑ Currently under moratorium
If the facility has had compliance problems during the permit cycle, please explain the status. See attached NOV.
Has the RO been working with the Permittee? ® Yes ❑ No ❑ N/A
Have all compliance dates/conditions in the existing permit been satisfied? ® Yes n No ❑ N/A
15. Are there any issues related to compliance/enforcement that should be resolved before issuing this permit?
Yes ®No❑N/A
III. REGIONAL OFFICE RECOMMENDATIONS
1. Do you foresee any problems with issuance/renewal of this permit? ❑ Yes or Z No
2. List any items that you would like the NPDES Unit or Non -Discharge Unit Central Office to obtain through an
additional information request:
3. List specific permit conditions recommended to be removed from the permit when issued:
4. List specific special conditions or compliance schedules recommended to be included in the permit when issued:
Condition
Reason
Schedule condition for
submitting Residuals
Mangament Plan
Currently the facility has no residuals management plan.
Update acreage in
Attachment B
The acreage listed in the current Attachment B (9.0 acres) is not correct. See IV.
Additionl Regional Staff Review Items for 2000 permit modification acreage.
5. Recommendation: n Hold, pending receipt and review of additional information by regional office
® Hold, pending review of draft permit by regional office
n Issue upon receipt of needed additional information
n Issue
❑ Den (Please state reasons: )
Do uSigned by:
6. Signature of report preparer: 19 OM& Mafacti /—DoeriSig reed by:
Signature of regional supervi 5548B6c0255c47A... L- Stiii cr
Date: December 9, 2020
IV. ADDITIONAL REGIONAL STAFF REVIEW ITEMS
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A comprehensive compliance inspection was recently conducted by WSRO staff. Therefore, no site visit was conducted
for this permit renewal. The two items listed below require attention and action with this permit renewal.
1. The spray field area listed in the current permit Attachment B is not correct. According to the initial permit
issued in 1986 and correspondence in the Division's archive files, this system was originally designed and
permitted for 45,000 GPD flow with 30 spray heads covering approximately 9 acres. In year 2000 the permit
was modified to correct the permitted spray field based on what was installed. This included reducing the
number of spray heads from 30 to 18, reducing spray field area from 9 acres to 6 acres. The permitted flow was
also reduced accordingly, lowering from 45,000 GPD to a new permitted limit of 24,400 GPD.
According to correspondence in the Division's archive files, this modification occurred following a compliance
inspection which noted the discrepancy in spray heads installed versus spray heads originally permitted.
Division files indicate that a survey was required at that time to establish the new spray field area of
approximately 6 acres. The spray field area was measured on GIS to determine accuracy of the previously
permitted 6 acres. This measurement was completed in method consistent with spray field designs from the
mid-1980s (i.e., measurement around the parameter of spray field). The attached site map with measurements
FORM: WQROSSR 04-14 Page 2 of 3

DocuSign Envelope ID: 18280350-DD97-4275-B92A-B8E3A7EA3541
appears to confirm the previously accepted 6 acre spray field area by measuring the outside parameter of 18
head spray field.
However, it appears there was an oversight or typo generated during the 2006 permit renewal. When the permit
was renewed, the original 9 acres was reinserted in the system description and in the Attachment B instead of
the preciously reduced area of 6 acres. Two permitting events followed the 2006 renewal (a name change in
2009 and permit renewal in 2016). The acreage error in the system description and Attachment B was carried
over in both of these permitting events.
Since no modifications are being requested at this time, recommend correcting the permit Attachment B
and system description to list 'a 6 acre spray field' area as previously permitted in the year 2000 permit
correction modification. The additional 3 acres of permitted spray field area (12 spray heads) that were never
installed could be included in the renewed permit as "construction of" or it could be left out. Due to the
inaccuracy of spray field area determinations and the likely insufficient site/soil evaluations that occurred in
1986, plus the length of time without installation, it is recommended that this be removed and not included in
the permit renewal. A new design and evaluation should be required for any expansion of the existing 33+ year
old spray system.
It should be noted that the primary ORC recently conducted a calibration of the system. During this
calibration, the ORC measured spray head wetted area radius to be approximately 54 ft. This is within the
acceptable 10% variance of original design spec shown on the site plan of 60 ft. radius. However, the accuracy
of these measures is unknown. WSRO staff should continue to monitor field loading to determine if more
accurate loading (i.e., using wetted area only) results in noncompliance. Using the design specs of 60 ft. radius
with 18 spray heads, there would be approximately 4.7 acres of wetted area within the 6 acre spray field.
2. At the time of the compliance inspection, the facility did not have a Residuals Management Plan established.
Please include a permit schedule condition that requires the facility to produce an approved Residuals
Management Plan within 90 days of permit issuance.
FORM: WQROSSR 04-14 Page 3 of 3

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Forest Lakes Irrigation System
Calibration Report
Prepared by:
Research and Analytical Laboratories, Inc
January 20, 2020

On January 14, 2020, Research and Analytical Laboratories completed the steps for calibrating the irrigation system
at Forest Lakes Campground, located in Advance, NC. This system is comprised of a 0.408 million gallon effluent
holding pond, and two - 142 GPM centrifugal effluent dosing pumps supplying treated effluent to 18 spray heads.
No issues with the irrigation system were noted on the day of the calibration.
The field procedure for calibration of the irrigation system consisted of four steps: (1) measuring operating pressure,
(2) measuring sprinkler wetted diameter and comparing it to the manufacturers chart, (3) measuring system flow rate
and comparing it to the appropriate system documentation, and (4) calculating sprinkler spacing. Equipment utilized
for this calibration procedure included a pressure gauge mounted directly to the sprinkler housing, a 200ft measuring
wheel, flags far delineating wetted irrigation diameters, a 5 gallon bucket graduated in tenths of a gallon, and a
stopwatch.
Operating pressures were measured at two sprinkler locations across all three lateral lanes for a total of 6 pressure
readings. These readings were then averaged to obtain an average "system" operating pressure. All readings were
taken directly at the impact sprinkler heads after approximately 1.0 hour of irrigation to insure that all air had been
purged from the system and that a stable pressure had been reached.
Sprinkler wetted diameter measurements were taken alongside the pressure measurements at the same sprinkler
heads that were used for pressure measurement. There was no noticeable wind present in the irrigation field at the
time measurements were taken. Wetted radius measurements were taken at (4) separate locations from each
irrigation head corresponding to a North/South/East/West configuration. Flags were placed to mark the edges of the
wetted area and distances were then measured from the sprinkler riser to the flag location. All radius readings were
then averaged and then multiplied by (2) to give the average wetted diameter.
Irrigation system flow rates were measured directly at the spray head using the 5 gallon bucket and a stopwatch.
Flow measurements were taken at the same spray heads utilized for pressure and wetted diameter readings. Flow
rates in gallons per minute were determined at each location and then averaged to obtain a uniform flow rate across
the entire system.
The following worksheet was taken from the "Calibration and Uniformity Assessment for Animal Wastewater
Application — Stationary and Travelling Irrigation Systems" prepared by NC State University and the NC
Cooperative Extension.

Stationary Sprinkler System Calibration and Uniformity Data Sheet
Lard Owner: 4_ Farm. Noll 0 4, (
Nozzle Type ‘.54041`m.4itry
Manufacturer's Specific tons; •Gun/Sprinkler Model
Nozzle Diameter 7 in.
1. Measure Pressure (measured from at least two sprinklers)
b. NO$StIre.) Gi.in/Sprinkier) 1 ig5 psi
c, Pressure (Gun/Sprinkfer) 2 z'''7 psi
d. Pressure (Gun/Sprinkler) 3 „2 Psi
e, Average pressure
'27 psi
2,, Measure Wetted Radius (refer to Figure 6 or figure above)
Alt iligt wa.r
IJ
Sprinkler I SOnkier 2 Sprinkler 3
a. Side 1 average distance from sprinkler to wetted radius ST ft 52 ft 50 ft
b. Side 2 average distance from gun to wetted raolog 5-3_ ft 1ft ctf ft
c Side 3 average distance from sprinkler to wetted radius. ,CS ft •52 ft 5-3,ft
d. Side 4 average distance from gun to wetted radius ft51 ft s5it
e. Average wetted radius 51,ft _52- ft 5 - 3 ft
f. Compare sprinkler radius for 1 and 2 sprinkler 1 (2.e) $11
xi° /0
sprinkler 2 (2.e) ft
Is 2.f. between 90% and 110%? Jyes no
g, if "yes', average the wetted radius for sprinklers 1 and 2 and multiply by 2 to obtain
wetted diameter (WD) /c CP ft
(if "no", repeat for sprinkler 3 and compare against sprinklers 1 or:2 to see if betwe n 90% and 100%)
11, Wetted diameter from manufacturer's chart using pressure in i.e. Ljtt
Percent difference = field measured (2.g) /4 ft
manufacturers chart (2.h) /0 7 ft
is 2.i between 85% and 115%? Yes no (if "no" contact technical irrigation specialist)
X104 V,d2 %
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STATIONARY AND TRAVELING
IRRIGATION SYSTEMS
Stationary Sprinkler System Calibration and Uniformity Data Sheet (continued)
3. Determine Flow Rate, Q
a. Pressure from 1.e. o?'% psi
b. Flow rate from manufacturer's chart 1 S. 7 gpm
c. Flow rate from irrigation design documentationlwettable acreage documentation / 3.0 gpm
e. Percent difference = field measured (3.b) 15 9 gpm
X 100 = MO
Documentation (3.c) (3.'7 gprn
Is 3.e between 90% and 110% ? yes ono (if no contact technical Irrigation specialist)
Assess Uniformity
4. Calculate Percent Overlap and Check Pressure
Avoe.
a. Sprinkler Spacing l7f1 ft
b. Sprinkler Spacing (% of WD) = Sprinkler Spacing (4.a) M9 ft
175
X 100 -- °!4
Wetted Diameter (2.g) 10C ft
Is Sprinkler Spacing (% of WD) (4.b) between 50% and 70%? yes V no
c. Nozzle pressure from 1.e. 2 7 psi
d. Minimum pressure from manufacturer's chart for sprinkler model and nozzle .�7 $psi
e. Maximum pressure from manufacturers chart for sprinkler model and nozzle / psi _ /
Is Nozzle pressure (4.c) between the minimum (4.d) and maximum (4.e) chart pressure? !r yes no
If the answer to either question is' no° then uniformity is not acceptable. Contact an irrigation technical
specialist.
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