WQ0018755_Staff Report_20210901

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State of North Carolina
Division of Water Resources
Water Quality Regional Operations Section
Environmental Staff Report
Quality
To: ❑ NPDES Unit ® Non -Discharge Unit Application No.: WQ0018755
Attn: Lauren Plummer Facility name: Castle Bay WWTF
From: Helen Perez
Wilmington Regional Office
Note: This form has been adapted from the non -discharge fg acili , 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 site visit: 01/19/2021
b. Site visit conducted by: Helen Perez
c. Inspection report attached? ❑ Yes or ® No Report in Laserfiche
d. Person contacted: Joel Mingus and their contact information: (910) 270 - 1412 ext.
e. Driving directions: Follow US-17N from Wilmington to Hampstead, turn left on Hoover Road (SR 1569)and
follow for annroximately 2.0 miles and turn right onto Castle Bav Drive. Follow Castle Bav Drive to first uravel
road on the right and follow to WWTP.
2. Discharge Point(s): N/A
Latitude: Longitude:
Latitude: Longitude:
3. Receiving stream or affected surface waters: N/A
Classification:
River Basin and Subbasin No.
Describe receiving stream features and pertinent downstream uses:
11. PROPOSED FACILITIES: NEW APPLICATIONS - N/A
1. Facility Classification: (Please attach completed rating sheet to be attached to issued permit)
Proposed flow:
Current permitted flow:
2. Are the new treatment facilities adequate for the type of waste and disposal system? ❑ Yes or ❑ No
If no, explain:
3. Are site conditions (soils, depth to water table, etc) consistent with the submitted reports? ❑ Yes ❑ No ❑ N/A
If no, please explain:
4. Do the plans and site map represent the actual site (property lines, wells, etc.)? ❑ Yes ❑ No ❑ N/A
If no, please explain:
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5. Is the proposed residuals management plan adequate? ❑ Yes ❑ No ❑ N/A
If no, please explain:
6. Are the proposed application rates (e.g., hydraulic, nutrient) acceptable? ❑ Yes ❑ No ❑ N/A
If no, please explain:
7. Are there any setback conflicts for proposed treatment, storage and disposal sites? ❑ Yes or ❑ No
If yes, attach a map showing conflict areas.
8. Is the proposed or existing groundwater monitoring program adequate? ❑ Yes ❑ No ❑ N/A
If no, explain and recommend any changes to the groundwater monitoring program:
9. For residuals, will seasonal or other restrictions be required? ❑ Yes ❑ No ❑ N/A
If yes, attach list of sites with restrictions (Certification B)
Describe the residuals handling and utilization scheme:
10. Possible toxic impacts to surface waters:
11. Pretreatment Program (POTWs only):
III. EXISTING FACILITIES: MODIFICATION AND RENEWAL APPLICATIONS
1. Are there appropriately certified Operators in Charge (ORCs) for the facility? ® Yes ❑ No ❑ N/A
ORC: Kirkl n Fields Certificate #:996782 Backup ORC: Michael Cowell Certificate #:1007662
2. Are the design, maintenance and operation of the treatment facilities adequate for the type of waste and disposal
system? ® Yes or ❑ No
If no, please explain:
Description of existing facilities:
The Castle Bay WWTF is a 100,000 GPD dual train extended aeration activated sludge process with spray irrigation
disposal.
Influent wastewater enters a single 25,000 gallon aerated flow equalization tank through a single manually cleaned bar
screen and dual adjustable weirs for flow control to each train. A single 85 cfm blower provides aeration for this
equalization tank, and dual 50 gpm flow equalization pumps are used to transfer influent into the aeration tanks and are
controlled with a series of float switches. Dual 62,500 gallon aeration tanks are operated in parallel and aeration is
provided by three (3) positive displacement blowers and air headers with coarse bubble diffusers. Wastewater passes from
the aeration tank(s) into each of two (2) rectangular 8,333 gallon hopper -type clarifier units. Return activated sludge
(RAS) is conveyed to each aeration tank from a single air-lift pump with an associated surface skimmer. Clarified effluent
then passes to dual 35 ft2 tertiary filters with 140 cfm blowers and 525 gpm backwash pump(s) for each. During a
backwash cycle, solids removed during the backwash flow to a small mud well where float controlled, dual 90 gpm
backwash surge or mud well pumps are used to return the flow to the influent flow equalization tank.
Filtered effluent then passes through a dual bank Trojan® LTV 3000PTP for disinfection, past a Hach® in -line
turbidimeter with a Honeywell® chart recorder and is then transferred to a 5.4 MG effluent storage pond by dual 89 gpm
effluent pumps. If required, effluent with high turbidity is automatically diverted to a 500,000 gallon upset pond adjacent
to the WWTP. A small transfer pump is used to return any diverted water to the influent flow equalization tank for
retreatment. Waste activated sludge (WAS) is removed from the process as needed by manually operating control valves
on the RAS recycle line and diverting flow into a single 15,000 gallon aerated sludge storage tank.
Proposed flow: 100,000 gpd
Current permitted flow: 100,000 gpd
Explain anything observed during the site visit that needs to be addressed by the permit, or that may be important
for the permit writer to know (i.e., equipment condition, function, maintenance, a change in facility ownership,
etc.) N/A
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3. Are the site conditions (e.g., soils, topography, depth to water table, etc) maintained appropriately and adequately
assimilating the waste? ® Yes or ❑ No
If no, please explain:
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.)? ❑ Yes or ® No
If yes, please explain:
5. Is the residuals management plan adequate? ® Yes or ❑ No
If no, please explain:
6. Are the existing application rates (e.g., hydraulic, nutrient) still acceptable? ® Yes or ❑ No
If no, please explain:
7. Is the existing groundwater monitoring program adequate? ® Yes ❑ No ❑ N/A
If no, explain and recommend any changes to the groundwater monitoring program:
8. Are there any setback conflicts for existing treatment, storage and disposal sites? ❑ Yes or ® No
If yes, attach a map showing conflict areas.
9. Is the description of the facilities as written in the existing permit correct? ® Yes or ❑ No
If no, please explain:
10. Were monitoring wells properly constructed and located? ® Yes ❑ No ❑ N/A
If no, please explain:
I t . Are the monitoring well coordinates correct in BIMS? ® Yes ❑ No ❑ N/A
If no, please complete the following ex and table if necessary):
Monitoring Well
Latitude
Longitude
O / //
O / 11
O / //
O I II
O I //
O I /I
O I //
O I /I
Has a review of all self -monitoring data been conducted (e.g., DMR, NDMR, NDAR, GW)? ® Yes or ❑ No
Please summarize any findings resulting from this review: A review of NDMR/NDAR since 2017 show no violations.
Monitoring Wells #2 and #3 have had ammonia hits for the past several years. The wells are located near a managed
timber forest which is likelv contributing to the ammonia exceedances. The concentrations in the MWs greatly exceed the
effluent ammonia from the treatment plant.
Provide input to help the permit writer evaluate any requests for reduced monitoring, if applicable.
12. Are there any permit changes needed in order to address ongoing BIMS violations? ❑ Yes or ® No
If yes, please explain:
13. Check all that apply:
® No compliance issues ❑ Current enforcement action(s) ❑ Currently under JOC
❑ Notice(s) of violation ❑ Currently under SOC ❑ Currently under moratorium
Please explain and attach any documents that may help clarify answer/comments (i.e., NOV, NOD, etc.)
If the facility has had compliance problems during the permit cycle, please explain the status. Has the RO been
working with the Permittee? Is a solution underway or in place?
Have all compliance dates/conditions in the existing permit been satisfied? ❑ Yes ❑ No ® N/A
If no, please explain:
14. Are there any issues related to compliance/enforcement that should be resolved before issuing this permit?
❑Yes®No❑N/A
If yes, please explain:
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IV. REGIONAL OFFICE RECOMMENDATIONS
1. Do you foresee any problems with issuance/renewal of this permit? ❑ Yes or ® No
If yes, please explain:
2. List any items that you would like the NPDES Unit or Non -Discharge Unit Central Office to obtain through an
additional information request:
Item Reason
3. List specific permit conditions recommended to be removed from the permit when issued:
Condition Reason
4. List specific special conditions or compliance schedules recommended to be included in the permit when issued:
Condition Reason
5. Recommendation: ❑ Hold, pending receipt and review of additional information by regional office
❑ Hold, pending review of draft permit by regional office
❑ Issue upon receipt of needed additional information
® Issue
❑ Deny, kgAK. reasons: )
6. Signature of report preparer:
Signature of regional supervisor:
Date: 9/2/2021
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DocuSign Envelope ID: 1F3C4138-D08E-4F79-9045-CE5E6B8B4050
V. ADDITIONAL REGIONAL STAFF REVIEW ITEMS
This staff report was prepared for the minor modification application submitted on 08/23/2021 for the installation of a
new mechanical screen at the headworks of the Castle Bay WWTF. A routine inspection of the facility was conducted
on 01/19/2021 and no major issues were detected. There have been many improvements to this facility in the past few
years, as noted on the Staff Report for renewal in 2019. The addition of a mechanical screen will further enhance the
efficiency of wastewater treatment.
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