NC0020389_Permit Issuance_20001009

State of North Carolina
Department of Environment
and Natural Resources
Division of Water Quality
James B. Hunt, Jr., Governor
Bill Holman, Secretary
Kerr T. Stevens, Director
Mr. Keith Langdon
Benson Town Administrator
P.O. Box 69
Benson, North Carolina 27504
Dear Mr. Langdon:
4 •
NCDENR
NORTH CAROLINA DEPARTMENT OF
ENVIRONMENT AND NATURAL RESOURCES
October 9, 2000
Subject: Issuance of NPDES Permit NCO020389
Benson WWTP
Johnston County
In accordance with the Town of Benson's application for renewal of its municipal discharge permit, the
Division of Water Quality is forwarding herewith the Town's NPDES permit renewal. This permit is issued
pursuant to the requirements of North Carolina General Statute 143-215.1 and the Memorandum of Agreement
between North Carolina and the U.S. Environmental Protection Agency dated May 9, 1994 (or as subsequently
amended).
The Benson WWTP discharges in the Neuse River Basin (NRB). All streams in the NRB have been
designated as nutrient sensitive waters (NSW) as a result of algal bloom problems in the estuary. The North
Carolina Environmental Management Commission recently adopted rules establishing the Neuse River Basin
Nutrient Sensitive Waters Management Strategy for the reduction of phosphorus and nitrogen inputs. The point
source rule (15A NCAC 2B.0234) is intended to reduce total nitrogen (TN) discharges by 30% by 2003. All
facilities with permitted flow greater than or equal to 0.5 MGD are receiving a TN limit in this permit cycle.
A public hearing was held May 1, 2000 in Raleigh due to public interest generated as a result of the
renewal of this (and other) NPDES permits. This final permit incorporates some of the comments and concerns
raised during that hearing. The following changes were made:
• Due to the Division's concerns regarding operation and maintenance at the plant, the Division has required
Benson to complete a Wastewater Management Plan within 180 days of the effective date of the permit. The
details of the plan should include estimation of future flows, a facilities assessment, optimization plan, and
biosolids management plan. Please refer to the Wastewater Management Plan special condition in the permit.
• Benson must provide continuous effluent flow monitoring at the plant. Effluent flow monitoring is critical to
calculating total nitrogen loading to Hannah Creek and the Neuse River.
• A minimum of 2 feet of freeboard must be maintained in each of the lagoons (currently used as
equalization/sludge holding). A staff gauge must also be provided in each lagoon.
• The Town is in the process of reconfiguration/modification of the WWTP to incorporate biological nutrient
removal. Due to the complexities in operation of this process, the wastewater treatment plant classification
will be increased to Class IV (from the current rating of Class III). In order to allow the Town to budget for the
increased monitoring, the Division will phase in the Class IV monitoring requirement within one year of the
effective date of this permit.
• The Division encourages the Town, if they have not already done so, to contact the Division's Technical
Assistance and Certification Unit at [phone]. This Unit may be able to assist the Town with treatment
operation and maintenance questions or problems.
1617 MAIL SERVICE CENTER, RALEIGH, NORTH CAROLINA 27699-1617 - TELEPHONE [phone]/FAX [phone]
AN EQUAL OPPORTUNITY AFFIRMATIVE ACTION EMPLOYER - 50% RECYCLED/ 10% POST -CONSUMER PAPER
VISIT US ON THE WEB AT http://h2o.enr.state.nc.us/NPDES

Mr. Keith Langdon
Town of Benson
Page 2 of 2
• The Town should make every effort to allocate appropriate resources to fund any future or current wastewater
treatment plant maintenance requirements, expansions, and/ or nutrient offset payments.
If any parts, measurement frequencies, or sampling requirements contained in this permit are
unacceptable to you, you have the right to an adjudicatory hearing upon written request within thirty (30) days
following receipt of this letter. This request must be in the form of a written petition, conforming to Chapter 150B
of the North Carolina General Statutes, and filed with the Office of Administrative Hearings (6714 Mail Service
Center, Raleigh, North Carolina 27699-6714). Unless such a demand is made, this permit shall be final and
binding.
This permit is not transferable except after notice to the Division. The Division may require modification
or revocation and reissuance of the permit.
This permit does not affect the legal requirements to obtain other permits that may be required by the
Division of Water Quality, the Division of Land Resources, the Coastal Area Management Act, or any other federal
or local government.
If you have any questions concerning this permit, please contact Susan Wilson at telephone number (919)
733-5083, ext. 510.
Sincerely,
Kerr T. Stevens
cc: Mr. Roosevelt Childress, EPA
Raleigh Regional Office, Water Quality
Construction Grants & Loans Section
Point Source Compliance & Enforcement Unit
Aquatic Toxicology Unit
Technical Assistance and Certification Unit
Central Files
Iftaft"
Town of Benson Commissioners (letter only, same address as above)
Keith Dupree
Frederick Nelson
Charles L. Nordan
Ray G. Smith
Jack R. Littleton
M. Scott Barnes

Permit NCO020389
STATE OF NORTH CAROLINA
DEPARTMENT OF ENVIRONMENT AND NATURAL RESOURCES
DIVISION OF WATER QUALITY
PERMIT
TO DISCHARGE WASTEWATER UNDER THE
NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM
In compliance with the provisions of North Carolina General Statute 143-215.1, other lawful standards and
regulations promulgated and adopted by the North Carolina Water Quality Commission, and the Federal Water
Pollution Control Act, as amended, the
Town of Benson
is hereby authorized to discharge wastewater from a facility located at the
Benson WWTP
770 Hannah Creek Road (south of I-95)
Four Oaks
Johnston County
to receiving waters designated as Hannah Creek in the Neuse River Basin
in accordance with the discharge limitations, monitoring requirements, and other conditions set forth in
Parts I, II, III and IV hereof.
This permit shall become effective November 1, 2000.
This permit and the authorization to discharge shall expire at midnight on April 30, 2003.
Signed this day October 9, 2000.
Kerr T. Stevens, Director
Division of Water Quality
By the Authority of the Environmental Management Commission

Permit NCO020389 '
SUPPLEMENT TO PERMIT COVER SHEET
The Town of Benson is hereby authorized to:
1. Continue to operate an existing 1.5 MGD wastewater treatment facility with the following
components:
➢ Bar screen
➢ Grit removal
➢ Parshall flume with flow measurement
➢ Influent screw pumps
➢ Three extended aeration/oxidation basins
➢ Four secondary clarifiers
➢ Tertiary filters
➢ Chlorine contact basin
➢ Dechlorination equipment
➢ Post aeration
➢ Alum and lime storage/handling units
➢ Aerated sludge lagoon
➢ Two stabilization lagoons (also act as influent flow storage)
➢ Lagoon effluent return pump station
This facility is located at the Benson WWTP (770 Hannah Creek Road) near Four Oaks in
Johnston County.
2. Discharge wastewater from said treatment works at the location specified on the attached map
into Hannah Creek, classified C - NSW waters in Neuse River Basin.

Latitude: 35°23'22"
R1 C 0 0 2 0 3 8 9
Facility"
.'
Longitude: 78 30'03"
Location
& r ; WO
Quad #: F24NE
Receiving Stream: Hannah Creek
Town of Benson
Stream Class: C-NSW
WViTp
Subbasin:30404
North IF
SCALE 1:24000

A. (1.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS - FINAL
During the period beginning on the effective date of the permit and lasting until one year after the
effective date, the Permittee is authorized to discharge 1.5 MGD of municipal wastewater from
outfall 001. Such discharges shall be limited and monitored by the Permittee as specified below:
Effluent Characteristics
Lunits
Monitoring Requirements
Monthly
Average
Weekly
Average
Daily
Maximum
Measurement '
Frequency
'Sample Type
Sample
Location 1 ;
Flow
1.5 MGD
Continuous
Recording
Influent or
Effluent
BOD, 5. day (20°C)2
[April 1 - October 31]
BOD, 5 day (209C)2
[November 1 - March 31]
Total Suspended Residue?
5.0 mg/I
10.0 mg/I
30.0 mg/I
7.5 mg/I
15.0 mg/I
45.0 mg/I
3/Week
3/Week
3/Week
Composite
Composite
Composite
Influent
f luent &
Influent &
Effluent "I
Influent &
Effluent
NH3 as N [April 1- October 311
NH3 as N [November 1- March 31]
Dissolved Oxygen3
2.0 mg/I
4.0 mg/I
Week
3/Week
3Meek
Composite
Composite
Grab
Effluent
Effluent
Effluent
Dissolved Oxygen
3Meek
Grab
Upstream &
Downstream
Fecal Coliform (geometric mean)
200/100,ml
400/100 ml
3/Week
Grab
Effluent
Fecal Coliform (geometric mean)
3/Week
Grab
Upstream &
Downstream
Total Residual Chlorine
3Meek
Grab
Effluent
Total Nitrogen
(NO2-N + NO3-N + TKN) 4
No, Effluent Limit (mg/1)
'Weekly
Composite
Effluent
No Effluent Limit (lb/month)
Monthly
Calculated
Effluent
33,790 lb/year (Annual Mass Loading) 5
Annually
Calculated,
Effluent
Total Phosphorus 6
2.0 mg/L (Quarterly Ave rage)
Weekly
Composite
Effluent.
Temperature 2C
Daily
Grab
Effluent
Temperature (°C)
3Meek
Grab
Upstream &
Downstream
3/Week
Grab
Effluent
-Conductivity
Conductivity
3Meek
Grab
Upstream &
Downstream
Chronic Toxicity7
Quarterly
Composite
Effluent
Copper
2/Month
Composite
Effluent
Zinc
2/Month
Com osite
Effluent
'Silver
Quarter)
Composite
Effluent
Hg
6-9
Daily
Grab
Effluent
(Footnotes on next page)
Town of Benson
Permit No. NCO020389

a
A. (1.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS - FINAL
(Continued)
Footnotes:
1. Sample locations: E - Effluent, I - Influent, U - Upstream at NCSR 1211, D - Downstream at
(1) NCSR 1711 and (2) 1-95 culvert. Stream samples shall be grab samples and shall be
collected 3/Week during June - September and 1 /Week during the remaining months of the
year. Instream monitoring is provisionally waived in light of the permittee's
participation in the Lower Neuse Basin Association. Instream monitoring shall be
conducted as stated in this permit should the permittee end its participation in the.
Association.
2. The monthly average effluent BOD5 and Total Suspended Residue concentrations shall not
exceed 15% of the respective influent value (85% removal).
3. The daily average dissolved oxygen effluent concentration shall not be less than 6.0 mg/l.
4. See Special Condition A.(3.), Total Nitrogen Monitoring.
5. The annual mass loading limit for total nitrogen shall become effective with the calendar year
beginning on January 1, 2003 unless it is provisionally waived per Special Condition A.(4.),
Annual Limits for Total Nitrogen.
6. The quarterly average for total phosphorus shall be the average of composite samples collected
weekly during the calendar quarter (January -March, April -June, July -September, October -
December).
7. Chronic Toxicity (Ceriodaphnia dubia) P/F at 90%: January, April, July, and October [see
Special Condition A.(5)]. Toxicity monitoring shall coincide with metals and cyanide
monitoring.
8. The pH shall not be less than 6.0 standard units nor greater than 9.0 standard units and shall
be monitored daily at the effluent by grab sample.
There shall be, no discharge of floating solids or visible foam in other than trace
amounts.
Town of Benson
Permit No. NCO020389

A. (2.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS - FINAL
During the period beginning one year after the effective date of the permit and lasting until
expiration, the Permittee is authorized to discharge 1.5 MGD of municipal wastewater from outfall
001. Such discharges shall be limited and monitored by the Permittee as specified below:
Effluent Characteristics
Limits
Monitorviq Requirements
Monthly
Average
Weekly
Average
Daily
Maximum
Measurement
Frequency
Sample Type
Sample
Locationl
Flow
1.5 MGD
Continuous
Recording
Influent or
Effluent
BOD, 5 day (202C)2
[April 1- October 311
5.0 mg/I
7.5 mg/I
Daily
Composite
Influent &
Effluent
BOD, 5 day (202C)2
[November 1 - March 311
10.0 mg/I
15.0 mg/I
Daily
Composite
Influent &
Effluent
Total Suspended Residue2
30.0 mg/l
45.0 mg/l
Daily
Composite
Influent &
Effluent
NH3 as N [April 1 - October 311
2.0 m /I
Daily
Composite
Effluent
NH3 as N [November 1- March 311
4.0 m /I
Daily
Composite
Effluent
Dissolved Oxygen3
Daily
Grab
Effluent
Dissolved Oxygen
3/Week
Grab
Upstream &
Downstream
Fecal Coliform (geometric mean)
200/100 ml
400/100 ml
Daily
Grab
Effluent
Fecal Coliform (geometric mean)
3/Week
Grab
Upstream &
Downstream
Total Residual Chlorine
Daily
Grab
Effluent
Total Nitrogen
(NO2-N + NO3-N + TKN) 4
No Effluent Limit (mg/1)
Weekly
Composite
Effluent
No Effluent Limit Ib/month
( )
Monthly
Calculated
Effluent
33,790 lb/year (Annual Mass Loading) 5
Annually
Calculated
Effluent
Total Phosphorus 6
2.0 mg/L (Quarterly Average)
Weekly
Composite
Effluent
Temperature (2C)
Daily
Grab
Effluent
Temperature (2C)
3/Week
Grab
Upstream &
Downstream
Daily
Grab
Effluent
-Conductivity
Conductivity
3/Week
Grab
Upstream &
Downstream
Chronic Toxicity7
Quarterly
Composite
Effluent
2/Month
Composite
Effluent
-Copper
Zinc
2/Month
Composite
Effluent
Silver
Quarterly
Composite
Effluent
H8
6-9
Daily
Grab
Effluent
(Footnotes on next page)
Town of Benson
PCI"rnit No. NCOO2O389

A. (2.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS - FINAL
(Continued)
Footnotes:
Sample locations: E - Effluent, I - Influent, U - Upstream at NCSR 1211, D - Downstream at
(1) NCSR 1711 and (2) I-95 culvert. Stream samples shall be grab samples and shall be
collected 3/Week during June - September and 1 /Week during the remaining months of the
year. Instream monitoring is provisionally waived in light of the permittee's
participation in the Lower Neuse Basin Association. Instream monitoring shall be
conducted as stated in this permit should the permittee end its participation in the
Association.
2. The monthly average effluent BOD5 and Total Suspended Residue concentrations shall not
exceed 15% of the respective influent value (85% removal).
3. The daily average dissolved oxygen effluent concentration shall not be less than 6.0 mg/l.
4. See Special Condition A.(3.), Total Nitrogen Monitoring.
5. The annual mass loading limit for total nitrogen shall become effective with the calendar year
beginning on January 1, 2003 unless it is provisionally waived per Special Condition A.(4_),
Annual Limits for Total Nitrogen.
6. The quarterly average for total phosphorus shall be the average of composite samples collected
weekly during the calendar quarter (January -March, April -June, July -September, October -
December) .
7. Chronic Toxicity (Ceriodaphnia dubia) P/F at 90%: January, April, July, and October [see
Special Condition A.(5)]. Toxicity monitoring shall coincide with metals and cyanide
monitoring.
8. The pH shall not be less than 6.0 standard units nor greater than 9.0 standard units and shall
be monitored daily at the effluent by grab sample.
There shall be no discharge of floating solids or visible foam in other than trace
amounts.
Town of Benson
Permit No. NCO020389

A. (3.) TOTAL NITROGEN MONITORING
The Permittee shall calculate the annual mass loadinis of total nitrogen as the sum of monthly
loadings, according to the following equations:
(1) Monthly Mass Loading (lb/mo) = TN x Q x 8.34
where:
TN = the average total nitrogen concentration (mg/L) of the composite
samples collected during the month
Q = the total wastewater flow discharged during the month (MG/month)
8.34 = conversion factor, from (mg/L x MG) to pounds
(2) Annual Mass Loading (ib/yr) = E (Monthly Mass Loadings) for the calendar year
The Permittee shall report the total nitrogen concentration for each sample and the
monthly mass loading in the appropriate self -monitoring report and the annual mass
loading of total nitrogen in the December self -monitoring report for the year.
A. (4.) ANNUAL LIMITS FOR TOTAL NITROGEN
(a) The Neuse Nutrient Management Strategy rule for point sources (1) provides that
annual mass limits for total nitrogen shall be included in the permits for all
dischargers with permitted flows (as defined in the Strategy) greater than or equal to
0.5 MGD and that those nitrogen limits, including the limits in this permit, shall
become effective with the calendar year beginning on January 1, 2003.
(b) The Neuse rule also provides that members of a group compliance association shall
not be subject to individual annual mass limits for total nitrogen. At the time of permit
issuance, the Permittee had expressed interest in joining such an association.
Accordingly,
(1) the total nitrogen limit in Condition A(1) of this permit is deemed waived
provided that the following conditions are met:
(i) a formal agreement between the association and Environmental
Management Commission, as outlined in 15A NCAC 2B. 0234, is
established and is in effect; and
(ii) the Permittee is a party to said agreement; and
(iii) the association and the Permittee substantially conform with the
agreement.
(2) So long as the total nitrogen limit in Condition A. (1.) is waived, the group
nitrogen allocation established pursuant to the agreement referenced above and
any subsequent amendments is hereby incorporated as an enforceable part of
this permit.
(c) If the Division determines, at any time during the term of this permit, that these
conditions are not being met, it shall notify the Permittee in writing of this
determination and of its basis. The consequence of such a determination shall be that
the Permittee's annual mass limit for total nitrogen and its effective date shall be
reinstated immediately. The Division shall accept and consider written responses
received from the Permittee and/or the association within thirty (30) days of the
original notice before making a final decision and will provide that decision in writing.
Tovzi of Benson
Permit No. NCO020389

A. (4.) ANNUAL LIMITS FOR TOTAL NITROGEN (cont'd.)
(d) The Permittee shall notify the Division in writing within five (5) working days if, at any
time during the term of this permit, the Permittee elects not to join the association, or
if it withdraws or otherwise loses its membership in the association. Notification shall
be sent to:
NC DENR / Division of Water Quality / NPDES Unit
1617 Mail Service Center
Raleigh, NC 27699-1617
Footnote:
Neuse River Basin - Nutrient Sensitive Waters Management Strategy: Wastewater
Discharge Requirements (15A NCAC 2B. 0234).
A. (5.) CHRONIC TOXICITY PERMIT LIMIT (QRTRLY)
The effluent discharge shall at no time exhibit observable inhibition of reproduction or significant
mortality to Ceriodaphnia dubia at an effluent concentration of 90%.
The permit holder shall perform at a minimum, quarterlu monitoring using test procedures
outlined in the "North Carolina Ceriodaphnia Chronic Effluent Bioassay Procedure," Revised
February 1998, or subsequent versions or "North Carolina Phase II Chronic Whole Effluent
Toxicity Test Procedure" (Revised -February 1998) or subsequent versions. The tests will be
performed during the months of January, April, July, and October. Effluent sampling for this
testing shall be performed at the NPDES permitted final effluent discharge below all treatment
processes.
If the test procedure performed as the first test of any single quarter results in a failure or
ChV below the permit limit, then multiple -concentration testing shall be performed at a
minimum, in each of the two following months as described in "North Carolina Phase H
Chronic Whole Effluent Toxicity Test Procedure" (Revised -February 1998) or subsequent
versions.
The chronic value for multiple concentration tests will be determined using the geometric mean of
the highest concentration having no detectable impairment of reproduction or survival and the
lowest concentration that does have a detectable impairment of reproduction or survival. The
definition of "detectable impairment," collection methods, exposure regimes, and further statistical
methods are specified in the "North Carolina Phase II Chronic Whole Effluent Toxicity Test
Procedure" (Revised -February 1998) or subsequent versions.
All toxicity testing results required as part of this permit condition will be entered on the Effluent
Discharge Monitoring Form (MR-1) for the months in which tests were performed, using the
parameter code TGP3B for the pass/fail results and THP3B for the Chronic Value. Additionally,
DWQ Form AT-3 (original) is to be sent to the following address:
Attention: North Carolina Division of Water Quality
Environmental Sciences Branch
1621 Mail Service Center
Raleigh, North Carolina 27699-1621
Completed Aquatic Toxicity Test Forms shall be filed with the Environmental Sciences Branch no
later than 30 days after the end of the reporting period for which the report is made.
Test data shall be complete, accurate, include all supporting chemical/physical measurements
and all concentration/response data, and be certified by laboratory supervisor and ORC or
approved designate signature. Total residual chlorine of the effluent toxicity sample must be
measured and reported if chlorine is employed for disinfection of the waste stream.
To1Az1 of Benson
Perinit No. NCO020389

A. (5.) CHRONIC TOXICITY PERMIT LIMIT (QRTRLY) (cont'd.)
Should there be no discharge of flow from the facility during a month in which toxicity monitoring
is required, the permittee will complete the information located at the top of the aquatic toxicity
(An test form indicating the facility name, permit number, pipe number, county, and the
month/year of the report with the notation of "No Flow" in the comment area of the form. The
report shall be submitted to the Environmental Sciences Branch at the address cited above.
Should the permittee fail to monitor during a month in which toxicity monitoring is required,
monitoring will be required during the following month.
Should any test data from this monitoring requirement or tests performed by the North Carolina
Division of Water Quality indicate potential impacts to the receiving stream, this permit may be re-
opened and modified to include alternate monitoring requirements or limits.
NOTE: Failure to achieve test conditions as specified in the cited document, such as minimum
control organism survival, minimum control organism reproduction, and appropriate
environmental controls, shall constitute an invalid test and will require immediate follow-up
testing to be completed no later than the last day of the month following the month of the initial
monitoring.
A. (6.) WASTEWATER MANAGEMENT PLAN
No later than 180 days after the effective date of this permit, the Permittee shall submit to the
Division a wastewater management plan. The plan shall include, at a minimum, the following
elements:
Future flows. Provide estimates of wastewater flows and characteristics for the
next 10-20 years and the basis for those estimates, including assumptions and
calculations.
Facilities assessment. Describe deficiencies and operational difficulties in the
existing collection system or treatment facility which affect performance or permit
compliance, and identify potential improvements to correct those. At a minimum,
evaluate the following considerations:
• inflow and infiltration,
• headworks performance,
• diversion of wasteloads during peak flows,
• equipment repairs and preventative maintenance,
• removal of accumulated solids, wastes, other debris
Optimization plan. Develop a strategy for optimization, rehabilitation, expansion
and/or replacement of the collection and/or treatment system to achieve optimum
performance. Identify specific measures and key tasks, including those in the
above facilities assessment, and provide an estimated schedule for completion of
each.
Biosolids management plan. Develop an operations protocol to be used or describe
the protocol currently used for managing septage/ biomass in the treatment
system, including associated solids wasting and disposal, to promote optimum
treatment system performance. Identify operating parameters to be used and
target values or ranges of values where appropriate.
Town of Bem-ion
Permit No. NCO020389

A. (7.) LAGOON FREEBOARD HEIGHT REQUIREMENT
A minimum of 2 feet of freeboard height must be maintained in the lagoons (currently used for
equalization/sludge holding). A staff gauge must be placed in each lagoon and the height
recorded daily.
A. (8.) EFFLUENT FLOW MONITORING
Continuous effluent flow monitoring must be provided at the plant.
Town of Benson
Permit No. NC0020389

Summary and
Recommendations
Facility Description
Neuse River Basin Public Hearings
May 1, 2000
Town of Benson
Benson WWTP
NCO020389
Benson operates a 1.5 MGD wastewater treatment facility consisting of a bar screen, grit removal,
parshall flume with flow measurement, influent screw pumps, three extended aeration/oxidation
basins, four secondary clarifiers, tertiary filters, chlorine contact basin, dechlorination, post aeration,
alum and lime storage/handling units, aerated sludge lagoon and 2 stabilization lagoons (that also act
as influent flow storage) with a lagoon effluent return pump station.
Permit Summary
The facility must meet limits of 5 mg/1 BOD5 (summer) and 2 mg/1 NH3-N (summer). The permit
also has a 2 mg/1 total phosphorus limit. A 33,790 lb/yr annual nitrogen load has been required
with this draft permit based on the revised nitrogen allocation. Benson is a member of the LNBA
and has proposed to become a member of the Neuse Nutrient Trading Association. Copper, silver
and zinc monitoring has been added to this draft permit.
Benson is currently operating under a Special Order by Consent (SOC) and has a relaxed limit for
total flow (i.e., the Town is required to make improvements to plant via inflow/infiltration (1/1)
reduction and come into compliance with the flow limit by Sept. 2000).
The Town discharges to a stream that is listed on NC's 303d list and is biologically impaired.
Additionally, numerous instream DO values have been recorded below 5 mg/l.
DWQ has concerns about Benson's future growth plans, although the Town has received
speculative limits for a discharge into the adjacent Cape Fear River Basin.
During the site visit by DWQ on April 27, it was noted that flow does not appear to be accurately
monitored. This is because when elevated flow conditions arise, flow is diverted to the "equalization
lagoons" prior to the flow monitoring area. Flow is pumped from the equalization lagoons to the
screw pumps (bypassing the flow meter). Accurate flow measurements must be determined in order
to properly assess exact nutrient load from the plant (*recommend that hearing officer specify that
effluent monitoring must be conducted. Influent monitoring should at minimum be estimated).
Comments
• Heather Beard (NRF) — concern over discharge into impaired creek, concern over
numerous operation and maintenance problems, concern over deficiencies in pretreatment
data and "falsification" of pretreatment data which lead to an assessment, concern that Town
needs to be more aggressive in planning further expansion and upgrades.
• NRF recommends more oversight of Town's pretreatment program
• NRF recommends Town become more serious re. planning and make immediate effort to
proceed with planning for growth demands.
• Keith Langdon, Benson — Have made progress on addressing inflow/infiltration issues, are
about to complete construction to assist with nitrogen removal, state $$s spent on projects,

have to balance competing issues for limited resources, accept responsibility that infrastructure
improvements will be ongoing process, proud of the performance record of plant and
acknowledge that paper work has sometimes been deficient, have contracted with The Wooten
Company to complete the Town's 201 Facility Plan for future expansion, disagrees with
DWQs requirement to monitoring silver, copper, and zinc with this permit renewal — feels
resources would be better used elsewhere.
Response and Discussion
DWQ acknowledges that this discharge is into a creek with DO levels documented at less than
5 mg/1; this creek is classified as "swamp", so the depressed DO's may be due to natural
conditions. Hannah Creek was not listed on the state's 303d list. However, should the facility
expand, DWQ may not consider Hannah. Creek as a discharge site. Additionally, any
expansion would require that the facility meet tertiary treatment levels. The recent inspection
noted O&M problems and a Notice of Violation is being submitted to the facility; should
corrections not be made to the plant, DWQ may pursue enforcement. A pretreatment audit is
conducted 1/year; [RRO and Pretreatment Unit has expressed concerns with regard to record
keeping and are in the process of further investigation] ***Should problems recur with
pretreatment, then enforcement may be pursued via the pretreatment requirements. A
recommendation regarding documentation of financial commitment to, and planning for,
future wastewater needs has been discussed with the hearing officer. Another special
condition regarding some specific maintenance requirements has been recommended to be
placed in the permit (flow measurement, lagoon freeboard height, headworks maintenance,
etc.).
DWQ is encouraged that Benson is working on the 201 Facility Plan for expansion. The
NPDES Unit does not recommend that any of the requirements from the draft be eliminated.
Also, the question has arisen as to the classification of the facility after the modifications for
nutrient removal have been put in place. Currently, Benson is a Class III facility — with
nutrient removal current rules specify that the classification will go to Class IV (although flow
is under 2.5 MGD). The NPDES Unit recommends that this either be phased in after a year
or be phased in with any permit request for expansion.
• The Raleigh Regional Office recommended via memo dated 6/14/00 that a minimum of 2 ft.
of freeboard be maintained in the facility's lagoons and a staff gauge (or similar instrument to
measure freeboard height) be permanently placed at each lagoon.
Recommended Actions)
NPDES Unit recommendations listed in responses and summarized below:
Phase in monitoring requirements for Class IV within 1 year.
Require minimum of 2 feet of freeboard height and staff gauges within each lagoon.
Require continuous effluent flow monitoring.
Require financial commitment for expansion.
0 Issue permit with attached Special Condition.

A. (_.) WASTEWATER MANAGEMENT PLAN
No later than 180 days after the effective date of this permit, the Permittee shall submit to
the Division a wastewater management plan. The plan shall include, at a minimum, the
following elements:
• Future flows. Provide estimates of wastewater flows and characteristics for
the next 10-20 years and the basis for those estimates, including assumptions
and calculations.
Facilities assessment. Describe deficiencies and operational difficulties in the
existing collection system or treatment facility which affect performance or
permit compliance, and identify potential improvements to correct those. At
a minimum, evaluate the following considerations:
• inflow and infiltration,
• beadworks performance,
• diversion of wasteloads during peak flows,
• equipment repairs and preventative maintenance,
• removal of accumulated solids, wastes, other debris
• Optimization plan. Develop a strategy for optimization, rehabilitation,
expansion and/or replacement of the collection and/or treatment system to
achieve optimum•performance. Identify specific measures and key tasks,
including those in the above facilities assessment, and provide an estimated
schedule for completion of each.
• Biosolids management plan. Develop an operations protocol to be used or
describe the protocol currently used for managing septage/ biomass in the
treatment system, including associated solids wasting and disposal, to
promote optimum treatment system performance. Identify operating
parameters to be used and target values or ranges of values where
appropriate.

June 14, 2000
MEMORANDUM
TO: Dave Goodrich
FROM: Ted Cashion
`A
L,,r�,t-1' ,
�J
J
THROUGH: Ken Schuster
SUBJECT: Administrative Letter for an Addition to the Benson WWTP
NPDES Permit NCO020389
The Town of Benson has 2 lagoons at the WWTP. One is for equalization/sludge
storage, one is for sludge storage. The NPDES permit does not require 2 feet of
freeboard in these lagoons. Previous site visits have shown levels <2 feet of freeboard.
We are requesting an administrative letter requiring a minimum two foot freeboard be
added to this permit for each lagoon. Also, we would like the permit to state that some
sort of measuring device be put in place to read the freeboard. We feel that the
administrative letter would help prevent potential problems.
If questions call me at 571-4700 ext. 250.
cc: Ken Schuster
Kevin Barnett
benson2.mem
J J N 2 2 2000

Re: freeboard
Subject: Re: freeboard
Date: Wed, 07 Jun 2000 08:38:20 -0400
From: Sue Homewood <[e-mail]>
Organization: DWQ
To: Susan Wilson <[e-mail]>
its 19 inches for typical anaerobic lagoons on swine farms, can be 26 inches
if its a newer lagoon. for other non -discharge lagoons (all types) we
usually require 2 feet.
sue
Susan Wilson wrote:
> is the standard free board height recommended as 19 inches? is this for
> all lagoon types?
Sue Homewood
Environmental Engineer
NCDENR - Division of Water Quality
Non -Discharge Permitting Unit
1617 Mail Service Center
Raleigh, NC 27699-1617
919-733-5083 extension 502
fax: [phone]
Mailto:[e-mail]
1 of 1 6/7/00 9:00 AM

May 16, 2000
Mr. Keith Langton, Town Manager
Town of Benson
303 East Church Street
Benson, NC 27504
DRAFT
D d
a
MAY 2 5 = f
DEAR - WATER QUALITY
--MiNT SOURCE BRANCH
SUBJECT: NOTICE OF VIOLATION/
Compliance Evaluation Inspection
Town of Benson WWTP
NPDES Permit No. NCO020389
Johnston County
Dear Mr. Langton:
Enclosed is a copy of the Compliance Evaluation Inspection conducted Apra
26,- 2000. The subject inspection was performed by several staff members
representing various regional offices of the Division of Water Quality. Conducting
the inspection were Belinda Henson and Dale Lopez of the Fayetteville Regional
Office and Ted Cashion, Jenne Sowell, Robin Simpson and Mitchell Hayes of the
Raleigh Regional Office. The cooperation of Mr. John Alt the "ORC" of the facility
was greatly appreciated. A violation was noted for the following NPDES permit
condition, Part II Section C.2.Pt_oper Operation
and MaintP.,a,,,.o - "The
permittee shall at all times properly operate and maintain all facilities and systems
of treatment and control (and related appurtenances) which are installed or used by
the permittee to achieve compliance with the condition of this permit."
The following summary of the inspection is noted:
The facility has one industry, Chicapi, with an average flow of 0.6 GPD.
This industry is responsible for 40-50% of the influent flow. The industry
produces woven material for hospital usage. It has an air flotation
pretreatment system. Chlorination is not used. Does the Town have a
pretreatment program??????
2. The plant is equipped with a influent Equalization Basin. When influent flow
exceeds 1.8 MGD the gates will automatically open and the flow is diverted
into the basin.

-continued-
3. The flow travels through a manual bar screen and then through an automatic bar screen. All
screenings are disposed of through the Johnston county landfill. There were paper products
(screenings) located on the ground beside the bar screen. Removal of these screenings from
this area and proper disposal is needed. Drainage from stock piled screenings should be
routed back into the facility. Such "on the ground" storage is not viewed as proper
screenings management.
4. Septage haulers are allowed to dispose of wastewater.into the facility. The average amount
is 20,000 gallons/month. It is recommended that the septage hauler waste is analyzed to
eliminate adverse affects to the facility. It is recommended that septage be discharged at the
headworks of the plant to allow complete treatment.
5. The Town has eight (8) lift stations. A portable generator is utilized when necessary. 'The
plant generator is believed to be under powered for the facility with a output capacity only
a 150 KVA. The ORC indicated that plans are to replace this generator with a 450 KVA in
the next fiscal year. It is recommended that enough portable generators should be on hand
to supply power to all lift stations in case of an emergency.
6. The grit removal system was not operational and had not been for approximately two (2)
weeks as per Mr. Alt. The facility had not notified the Raleigh Regional office concerning
this. As stated in the NPDES permit Part H. 9. Noncompliance Notification
"The permittee shall report by telephone to either the central office or the appropriate
regional office of the Division as soon as possible, but in no case more than 24 hours or on
the next working day following the occurrence or first of the occurrence of any of the
following:
b. Any process unit failure, due to known or unknown reasons, that render the facility
incapable of adequate wastewater treatment such as mechanical or electrical failures
of pumps, aerators, compressors, etc."
7. The alarm system at the facility was not inclusive of all components and pumps at the
facility. It is strongly recommended that telemetry installed at the facility as well as the lift
stations for all key components to alert municipal staff of equipment failure and high water
flow indications.
8. The influent flow meter which was an ISCO 3210 Ultrasonic did not appear to have a recent
calibration. Flow meter calibration records were not available. As stated in the
Administrative Code Section: 15A NCAC 2B .0505(b)(1)"Devices selected shall be capable
of measuring flows with a maximum deviation of less that 10 percent from true discharge
volumes. Flow measurement devices shall be accurately calibrated at a minimum of once
per year and maintained to ensure that the accuracy of the measurements is consistent Edith
the accepted capability of that type of device." It is advisable that the flow meter calibration
document contain the % error before and after calibration by the technician. Failure to

-continued -
provide proper and timely calibration is considered a violation.
9. The stilling well used to read the flow appeared to have some sludge in it which will block
the signal necessary for accurate flow measurement. Cleaning the stilling well should be
completed immediately. Please be aware that lack of maintenance in this area could lead to
false flow violations resulting in fines.
10. Three (3) screw pumps are used to pump the wastewater into the oxidation ditches. All
pumps appeared to be operational. One (1) pump is used under ordinary conditions. Screw
pump 91 appeared to have an unusual sound when it was turned on. Possible repairs maybe
needed on this pump. Further evaluation should be performed to access the possible
problems and prevent undue repairs and expenses.
11. The wastewater from the equalization basin is pumped in at the area after the influent has
been pumped by the screw pumps. The flow is not properly metered since the flow from the
equalization basin is not metered. All flow coming into the plant should be properly metered
for a total flow. This must be corrected within 60 days of receipt of this report.
12. The influent flows into three oxidation ditches. Oxidation ditch #1 was under repairs at the
time of the inspection for maintenance and some mechanical changes. During the inspection
it was noted that grit and other material was amassed in piles in this ditch. Before this ditch
is put back into service this material should be removed to increase the capacity of space for
wastewater as well as improved treatment. Plans are to use oxidation ditch #2 as an anoxic
zone for nitrogen removal which means the flow will travel to #2 ditch and then to #1 and
#3 in parallel to complete aeration. All aerators appeared to be operational. A
recommendation to place fencing around the oxidation ditches to assist with safety was made
during the inspection. Painting the power boxes and other needed components in this area
is suggested. The Mixed Liquor Suspended Solids (MLSS) content ranges from 2000 mg/1
to 2500 mg/l. The analyses for MLSS is performed twice a week.
13. Lime is added into the oxidation ditches when needed for ammonia reduction. The lime tank
on site appeared to need painting and proper maintenance now could eliminate major repairs
and cost in the future. It has not been necessary to use the lime in 6-8 months.
14. The facility had four (4) clarifiers. There was not a operable sludge judge on site to monitor
sludge blankets. At least two (2) sludge judges should be purchased to assist in operation
of the clarifiers. Sludge depths should be monitored daily to assist with overall wastewater
treatment. There appeared to be some floatable paper products in the clarifier which blocked
the flow over the weirs in a few area. The floatable items should be removed on a daily basis
to eliminate this.. In clarifier #2 the motor had an unusual sound which could be a symptom
of necessary repairs. The motor should be checked for possible problems. The catwalks and
railings appeared to have paint worn from the surface. Maintenance in these areas should
be addressed as soon as possible to eliminate major repairs and cost in the future.

-continued-
15. An alum tank on site is utilized for solids settling in the clarifiers if necessary. Alum is not
used at this time. A containment wall is located around the tank to prevent spillage onto the
ground. The drain located inside the wall will drain to the scum well. This drain should be
closed to prevent, spillage from slugging the plant. Rainwater should be released as needed.
16. The effluent filters are made of multimedia sand, gravel and anthracite. There appeared to
be some floatable solids (not excessive) located on the surface of the water. Increased
backwash time may be necessary to eliminate this. The electrical boxes for the filters were
open which appeared to be unsafe. As per conversation with Mr. Alt, the electrical boxes
were open due to monitoring the system because of various problems with one being not able
to automatically control the operations of the filters. They can only be manually operated.
The operation of the filters should be evaluated by the town's engineers and plans developed
to correct any operational problems.
17. Chlorine is added for disinfection of the effluent. The system will automatically switch
cylinders when one is empty. A ton cylinder will last approximately five (5) months. A flow
paced chlorine system is suggested to assist in adequate disinfection without over dosage:
18. The chlorine contact tank is cleaned annually. jPlease note that solids should never be
allowed to accumulate over 12 inches in depth, ever that accumulation may cause effluent
violations.
19. Two (2) effluent pumps are used with one (1) leaking profusely. Repairs should be made as
soon as possible to eliminate this leakage. The pumps also appeared to have paint worn from
the surfaces. Painting of these surfaces could eliminate major repairs in the future.
20. The post aeration tank is the last phase of the wastewater treatment. Dried solid material
appeared on the side of the tank and on a step ladder leading the inspectors to believe that
solids had spilled over in this tank previously. We highly recommend that the chlorine
contact tank and the post aeration tank are cleaned to ensure the best quality effluent is
discharged as well meeting NPDES permit requirements. Both grab and composite sampling
is completed at the end of the post aeration tank with the exception of the .chlorine residual
sample which is collected at the end of the chlorine contact chamber. All sampling should
be done at one point. Soda ash is added for pH adjustment in this tank.
21. The effluent appeared to be a little cloudy.
22. The effluent outfall was easily accessible. As a reminder all grass and weeds should be
maintained adequately to continue accessibility to the effluent outfall.
23. An aerated sludge lagoon has been utilized since the year "1995" with no sludge disposal.
The aerated lagoon had three (3) 15 horsepower floating surface aerators. This facility
should find a way to popery dispose of sludge before problems are created for the treatment
of the wastewater. A plan for sludge disposal should be implemented immediately. There

-continued -
appeared to be some duckweed not excessive floating on the surface of the wastewater. It
is requested that the Town provide the total sludge volume ahead.
24. The equalization lagoon and the #3 sludge holding lagoon are recommended to be dredged
and all paper products located on the grounds outside the lagoons should be properly
disposed of. Removing trash and debris from the ground is a basic maintenance
requirement.
25. The influent composite sampler temperature was over 5 Degrees Celsius. The effluent
composite sampler temperature appeared to be adequate at 4 Degrees Celsius. Composite
sampler temperatures should be maintained at 0-4 Degrees Celsius. The composite
sampler containers were enclosed in a refrigerated unit. There was no protection from the
elements for the refrigerated unit. Without the added protection of some type of enclosure
adequate holding temperatures may be difficult to maintain during hot_ and humid weather.
During the inspection it was noted that during composite sampling one (1) sample was
collected every 38 minutes. Based on Administrative Code Section: 15A NCAC 2B. 0503-
"Composite sample (d) Constant time/constant volume - a series of grab samples of equal
volume collected over a 24 hour period at a constant time interval. This method may be used
in situations where effluent flow rates vary less than 15 percent. The grab samples shall be
taken at intervals of no greater than 20 minutes apart during any 24 hour period and must be
of equal size and of no less that 100 milliliters. Use of this method requires prior approval
by the Director". The influent composite sample can be collected based on this type of
sampling but the effluent must choose one of the other types of composites which area
proportiona . Please contact the Raleigh Regional Office for further information.
26. The facility is presently under a Special Order by Consent (SOC) with modified limits for
flow which expire June 1, 2000. A copy of the SOC was not on site. The NPDES permit
was effective April 1, 1994 and expired -January 31, 1999 and was on site for review.
27. Laboratory records were reviewed for the months October through December 1999 and
compared to Discharge Monitoring Reports (DMRs): The records appeared to be adequate.
28. A compliance evaluation analysis report for the period March 1999 through February 2000
did not reveal any violations. I
29. The on site laboratory performs all required NPDES permit parameters except Toxicity and
Total Nitrogen. The Toxicity parameter is analyzed by the commercial laboratory "Water
Technology and Controls" and Total Nitrogen is analyzed by "Southern Testing".
30. The laboratory on site was inspected during this time and the following items were noted:
a. The BOD incubator temperature was 19.6 Degrees Celsius which is adequate. The
temperature range for the incubator should be 20 +/- 1 Degrees Celsius.

f
-continued-
b. The drying oven for the Total Suspended Solids analyses was adequate at 103.6
Degrees Celsius. The temperature range for the oven is 103-105 Degrees Celsius:
C. Calibration records for the pH parameter were adequate. 'pH buffers were checked
and the pH buffer 7.0 had expired January 26, 2000. The buffer should be discarded
and an unexpired pH buffer 7.0 should be purchased -immediately.
d. Calibration logs for weights were adequate with the following weights used: 100
milligram, 1 gram, 5 grams, 10 grams.
Please respond in writing -to the following items: 6, 8-12, 149 169 20, 23, 25 explaining
the actions to resolve these problems. Please respond on or before June 30, 2000.
Violations of the NPIDES permit are enforceable by our Division. Violations can be accessed
up to $25,000/day/violation.
As a reminder the Division's Technical Assistance and Certification Unit is available upon
request to provide assistance to the Town with technical problems at no cost. You can contact
Dwight Lancaster, Supervisor, at 919-733-0026.
If you or your staff have any questions please contact Mr. Cashion or other`water quality
staff at 919-571-4700.
cc: Laboratory Certification

Brief Facility Description:
"M I Iwo I =1648 -
MINI1104•• •• a.. ',. •�MeN.�1
FACILITY SITE REVIEW
(!eD No N/A 1. Treatment'units properly operated and maintained.
es No N/A 2. Standby power or other equivalent provision provided.
Yes. �Z� N/A 3. Adequate alarm system for power or equipment failure available.
4. Sludge disposal procedures appropriate:
Yes No N/A a. Disposal of sludge according to regulations
Yes No N/A b. State approval for sludge disposal received.
Yes (S� N/A 5. All treatment units other than backup units in service.
Yes No � 6. Sufficient sludge disposed of to maintain treatment process equilibrium.
Yes No N/A 7. Adequate number of qualified operators on staff.
Yes No N/A 8.
Established procedures available for training new employees.
No N/A 9.
Adequate spare parts and supplies inventory maintained.
Yes N/A 10.
a. Hydraulic overflows and/or organic overloads experienced
Yes (N N/A
b. Untreated bypass discharge occurs during power failure.
Yes N/A
c. Untreated overflows occurred since last inspection.
Yes o N/A 11. Plant has general safety structures such as rails around or covers over
tanks, pits, or wells.
Yes (Ro N/A 12. Plant is generally clean, free from open trash areas.

Page 2
I Screening:
No N/A a. Manual
es No N/A b. Mechanical
(UP No N/A c. Buildup of debris
DNo N/A d. Screenings properly disposed of.
14. Grit Removal: nr-A e p e rct� ; e nl I
Yes No N/A a. Excessive organic content in the grit chamber
Yes No N/A b. Excessive odors
Yes No N/A c. Grit properly disposed of.
15. Primary clarifier:
Yes
No
1 /
a.
Excessive gas bubbles
Yes
No
N/A
b.
Black and odorous wastewater
Yes
No
N/A
c.
Poor suspended solids removed
Yes
No
N/A
d.
Excessive buildup of solids in center well of circular clarifier
Yes
No
N/A
e.
Weirs level
Yes
No
N/A
f.
Weir blockage
Yes
No
N/A
g.
Evidence of short circuiting
Yes
No
N/A
h.
Lack of adequate scum removal
Yes
No
N/A
i.
Excessive floating sludge
Yes
No
N/A
j.
Broken sludge scraper.
16. Trickling Filter: .
Yes
No
(95�
a.
Trickling filter ponding(indicating clogged media)
Yes
No
N/A
b.
Leak at center column of trickling filter's distribution arms
Yes
No
N/A
c.
Uneven distribution of flow on tricklina filter surface
Yes
No
N/A
d.
Uneven or discolored growth
Yes
No
N/A
e.
Excessive sloughing of growth
Yes
No
N/ A
f.
Odor
Yes
No
N/A
g.
Clogging of trickling filter's distribution arm orifices ;
Yes
No
N/A
h.
Filter flies, worms, or snails.
17. Rotating Biological Contactors (RBC):
/ Yes No i a. Development of white biomass on rotating biological contactor
media
Yes No N/A b. Excessive sloughing of growth
Yes No N/A' c. Excessive breakage of rotating disks or shafts in RB C units_.
Yes No N/A d. Excessive breakage of paddles on brush aerators
Yes No N/A e. Shaft, bearing. drive gear, or motor failure on disk or brush aerators.

Page 3
18. Activated Sludge Basins/Oxidation Ditches:
v
Yes
(g3)
N/A
a.
Dead spots
Yes
C b
N/A
b.
Failure of surface aerators
Yes
cis
N/A
c.
Air rising in clumps
Yes
62
N/A
d.
Dark foam or bad color
Yes
0
N/A
e.
Thick billows of white, sudsy foam
Yes
No
�T/A�
f.
Air rising unevenly
Yes
No
1/�
g.
Excessive air leaks in compressed air piping.
19. Stabilization Ponds/Lagoons:
Yes No N/A a. Excessive weeds including duckweed in stabilization ponds
Yes Q N/A b. Dead fish or aquatic organisms
Yes No N/A c. Buildup of solids around influent pipe
Yes (&) N/A d. Excessive scum on surface.
20. Secondary Clarifier:
Yes
o
N/A
a.
Excessive gas bubbles on surface
Yes
dO
N/A
b.
Unlevel overflow weirs
TJ6
No
N/A
c.
Weir blockage Sc. M C
No
N/A
d.
Evidence of short circuiting
Yes
No
N/�
e.
Excessive buildup of solids in center well of circular clarifier
Yes
No
N/A
f.
Pin floc in overflow
Yes
No
%t
g.
Ineffective scum rake
Yes
(Tes
N/A
h.
Floating sludge on surface
Yes
No
N/A
i.
Excessive high sludge blanket n e
Yes
No
N/A
j.
Clogged sludge withdrawal ports on secondary clarifier. -
21.
Filtration:
Yes
< sD
N/A
a.
Filter surface clogging
y
Yes
No
N/A
b.
Short filter run .
Yes
1i'
N/A
c.
Gravel displacement of filter media
Yes
KO
N/A
d.
Loss of filter media during backwashing
Yes
N/A
e.
Recycled filter backwash water in excess of 5 percent
Yes
C 0—
N/A
f.
Formation of mudballs in filter media.
22. Chlorination Unit:
Yes
N/A
a.
Sludge buildup in contact chamber
Yes
' T
N/A
b.
Gas bubbles
Yes
NO'
N/A
c.
Floating scum and/or solids
Yes
�'
N/A
d.
Inadequate ventilation of chlorine feeding room and storage area
Des
No
N/A
e.
NIOSH-approved 30 minute air pack
Yes
Q�)
N/A
f.
All standing chlorine cylinders chained in place to in H, 0
1Z s1No
N/A
Q.
All personnel trained in the use of chlorine
es )No
N/A
h.
Improper chlorine feed, storage, and reserve supply.

Page 4
Yes No <S7L�) 23. Ultraviolet radiation disinfection present and in use.
_ 24. Dechlorination:
Yes No C/P�% a. Improper storage of sulfur dioxide cylinders
Yes No N/A b. Inadequate ventilation of sulfur dioxide feeding room
Yes No N/A c. Automatic sulfur dioxide feed or feedback control not operating
properly.
25. Aerobic Digester: L—(z J•o o n
Yes * N/A a. Excessive foaming in tank
Yes Zg6) N/A b. Noxious odor .
Yes Q N/A c. Mechanical aeration failure
Yes No //A� d. Clogging of diffusers.
26. Anaerobic Digester:
Yes No N/ a. Floating cover tilting
Yes No N/A b. Gas burner inoperative
Yes No N/A c. Supernatant has a sour odor.
27.
Sludge Drying and/or disposal:
Yes
No
�/�
a.
Poor sludge distribution on drying beds
Yes
No
N/A
b.
Vegetation in drying beds
Yes
No
N/A
c.
Dry sludge remaining in drying beds
Yes
No
N/A
d.
Dry sludge stored on site
Yes
No
N/A
e.
Filtrate from sludge drying beds returned to front of plant
Yes
No
N/A
f.
Approved disposal site for the sludge
Yes
No
N/A
g.
Sludge land applied.
28. Filter Press:
Yes No a. High level of solids in filtrate from filter presses or vacuum filters
Yes No N/A b. Thin filter cake caused by poor dewatering
Yes No N/A c. Sludge buildup on belts and/or rollers of filter press
Yes No N/A d. Excessive moisture in belt filter press sludge cake.
29. Polishing Ponds or Tanks:
Yes No i D a. Objectionable odor, excessive foam, floating solids, or oil sheens on
water surface
Yes No N/A b. Solids or scum accumulations in tank or at side of pond
Yes No N/A c. Evidence of bypassed polishing ponds or tanks because of low
capacity.

Page 5
30. Plant Effluent:
Yes L q N/A a. Excessive suspended solids, turbidity, foam, grease, scum, color, and
other macroscopic particulate matter present
Yes (0 N/A b. Potential toxicity (dead fish, dead plant at discharge)
's) No N/A c. Outfall discharge line easily accessible.
31. Flow Measurement:
Yes
No
N/A
a.
Improper placement of flow measurement device
Yes
W
N/A
b.
Flow totalizer not calibrated
Yes
No
N/A
c.
Buildup of solids in flume or weir
Yes
No
N/A
d.
Broken or cracked flume or weir
Yes
No
N/A
e.
Improperly functioning magnetic flowmeter
No
N/A
f.
Clogged or broken stilling wells
Yes
(RD
N/A
g.
Weir plate edge corroded or damaged
Yes
No
N/A
h.
System not capable of measuring maximum flow
Yes
No
N/A
i.
Flow measurement error greater than +/- 10%.
32. Sampling:
No N/A a. Sampling and analysis completed on parameters specified by permit
es No N/A i b. Samples refrigerated during compositing
Yes No N/A c. Composite sample temperatures maintained at less than or equal to 4
degrees Celsius during sampling 5e C, 4
Yes No N/A d. Contract laboratory used for sample analysis.
RECORDKEEPING AND REPORTING
Yes No N/A 1. Records and reports maintained as required by permit.
es No N/A 2. All required information available, complete, and current.
es No N/A 3. Records maintained for') years and all sludge records maintained for 5
years.
Yes No N/A 4. Analytical results consistent with data reported on DMRs.
_ 5. Sampling and analyses data adequate and include:
es ` No N,1A a. Dates, times, and location of sampling
Yeses, No N/A b. Name of individual performing sampling
es-7No N/A c. Results of analyses and calibration
No N/A d. Dates of analyses
es No N/A e. Name of person performing analyses.

FILTER
BACKWASH HASTE CHLORINE
DECHLORINATION SYSTEM
CONTACT
BASIN
POST AERATION TANK
FILTERS
2 EFFLUENT
PUMPING
STATION
BACKWASH WATER STORAGE
FILTER BACKWASH
II �� �\-.,_SLUDGE
CLEAR WATER
ISLUDGE
WASTE
III
RECIRCULATION
11jIt AL\; \ \\
AERATION
1
TANK f3 —�
\�
IIIAL \ \ 1_ 1�.l
C A.
\°
�—
I
I�
1�I I
I I
ALUM
'k
I
I +�—
1 f2AR. UNITLING 6 I
AERATION
TANK 02
0
1 /
1
5 I
I
1
ISPLITT
D)
}
( '
LIME �❑0
1 IBOX
—i
0
1 UNITLING Ro
CLAR.
03.
8
AERATION
C #Ai
TANK f i -�
SCREW
PUMPS
9
IGRIT
INFLUENT 1 CHAMBER-,
BYHPASSTSCREEN
�-
ol
7 PARSHALL
SLUDGE HOLDING
LAGOON 03
EXHIBIT V-9
SAMPLING LOCATIONS
LAGOON EFFLUENT RETURN
AERATED
b� LAGOON fi
SLUDGE HOLDING
LAGOON f2 -1
9

Re: benson
Subject: Re: benson
Date: Mon, 27 Mar 2000 10:31:19 -0500
From: Marcia Lieber <[e-mail]>
Organization: NCDENR-DWQ
To: Susan Wilson <[e-mail]>
hi, the Town is compliant with their& mile stones so far, the next mile
stone date is March 30, 2000, when construction to the collection system
is completed. Iglet you know when/"If they can meet that date.
Susan Wilson wrote:
> Mrcia,
> could you verify if benson has been compliant with their SOC schedule?
> some dates are filled in (it looks like to me) but others aren't. if
> they go to hearing - we'll need this info.
I of 1 3/27/00 10:33 AM

AFFIDAVIT O _ UBLICATION
NORTH CAROLINA.
Wake County. ) Ss.
TO BE HELD BY
NORTH GkROLINA ENVIRONMENTAL MANAGEMENT COMMISSION
ing has been scheduled concerning the proposed renewal and, issuance of the following
nits:
iber NCO023841 to the City of Durham for the Durham North Water'Reclamation
tted in Durham (Durham County) for the discharge of treated municipal wastewater
Creek.
Iber N000Z0389 To the Town of Benson for the Benson Wastewater Treatment Plant
Jenson (Johnston County) for the discharge of treated municipal wastewater into
Iek.
tber NC0 M.M to Uniprop, Inc. for the Mill Run Mobile Home Park Wastewater
Plant located in Garner (Wake County) for the discharge of. treated domestic
into an unnamed tributary to swift Creek.
nber N00049662 to Heater Utilities for the Hawthorne Subdivision Wastewater
Plant located in Raleigh (Wake County) for the discharge of treated domestic
into Upper Barton Creek.
Iber NC0038to Riverview Mobile Home, Park for the Riverview Mobile Home Park
Treatment P784lant located in Raleigh (Woke County) for the discharge of treated
astewater into the Neuse River.
nber NCO064408 to Whitewood Properties, Inc. for the Neuse Crossing Wastewater
Plant located in Raleigh (Wake County) for the discharge of treated domestic
into the Neuse River.
nber NCO063746 to Ira D. Lee for the Deerchose Subdivision Wastewater Treatment
:din Wake Forest ( Wake County) for the discharge of treated domestic wastewater into
k.
fiber NC0060526to Pope Industrial Park I[, Ltd. forthe Pope Industrial Park Wastewater
Plant located in Raleigh (Wake County) for the discharge of treated domestic
into an unnamed tributary to Swift Creek.
e facilities has applied for renewal of their NPDES permit far the discharge of treated
municipal wastewater into waters of the Neuse River basin. On the basis of prel immary
and application of Article 21 of Chapter 143, General Statutes of North Carolina, and
standards and regulations, the North Carolina Environmental Management Commis
s to issue a NPDES permit for each facility sub)ect to specific pollutant ltations and
litions. The Director of the Division of Water Quality Pursuant to NCG5143 215.1(c) (3)
.an 15 CA r Section 0700 has determined that it is m The public interest that a
held to rece-rye aii pertinent public -comment on whether to issue, modify, or deny the
2E:
I will be corMucted in the following manner:
oration of North. Carolina Environmental Management Commission's Permitting
vill be Presented by the Division of Water Quality.
motion of the action for which each permit is required may be made by The applicant.
mment- Comments, statements, dato and other information may be submitted in writing
urine the meeting or may he presented orally at the meeting. Persons desiring to sceak
Th is intent at thetime of registration ai the meeting. So that al I persons desi ring to speak
lengthy statements may be IIm)ted at the discretion of the meeting officer. Oral
ns that exceed three minutes should be accompanied by Three written copies, which will
th Division staff at the time of registration.
�minafion Of persons Presenting testimony will not be allowed. however, the hearing
ask questions far clarification.
•ing record maybe closed at the conclusion of the meeting.
lay 1, 2000 at 7:00 P•m.
Archdale Building -Ground Floor Hearing Room
512 North Salisbury Street
Raleigh, North Carolina
rloN:
the draft NPDES permit(s) and a map showing the location of the discharge(i) are
,y writing or calling:
e Jackson
n of Water Ouolity/NPDES Unit
iervice Center
orth Carolina 27699-1617
number: 619) 733-5083, extension 538 - y
ations and other'information are on file at the Division of Water quality, 512 North
treet, Raom 925 of the Archdale Building in Raleigh, North Carolina and of the Division's
gional Office (3800 Barrett Drive in Raleigh). They may be inspected during normal
s. Copies of the information on file are available upon request and.payment of the costs of
on. All such comments and requests regarding this matter should make reference to the
nber(s) listed above.
rh 99. 211011 -.
Pus
Before the undersigned, a Notary Public of Johnston
County North Carolina, duly commissioned and authorized to
administer oaths, affirmations, etc., personally appeared Debra
Peebles who, being duly sworn or affirmed, according to law,
doth depose and say that she is Billing Manager -Legal
Advertising of THE NEWS AND OBSERVER PUBLISHING
COMPANY a corporation organized and doing business
under the Laws of the State of North Carolina, and publishing
a newspaper known as THE NEWS AND OBSERVER, in the
City of Raleigh, County and State aforesaid, the said
newspaper in which such notice, paper, document, or legal
advertisement was published was, at the time of each and
every such publication, a newspaper meeting all of the
requirements and qualifications of Section 1-597 of the
General Statutes of North Carolina and was a qualified
newspaper within .the meaning of Section 1-597 of the
General Statutes of North Carolina, and that as such she
makes this affidavit; that she is familiar with the books, files
and business of said corporation and by reference to the files
of said publication the attached advertisement for NC DEPT
OF DEHNR was inserted in the aforesaid newspaper on dates
as follows: 03/29/00
Account Number:' 73370152
books and files of the aforesaid Corporation and publication.
114
. . . . .................... ...... . . 41
Billing Manager -Legal Advertising
Sworn or affirmed to, and subscribed before me, this
30 day of MARCH , 2000 AD
In Testimony Whereof, I have hereunto set my hand
and affixed my official seal, the day and year aforesaid.
Notary Public
My commission expires 2nd day of July 2000.

- LONG TERM MONITORING PLAN REQUEST FORM
FACILITY: I`ow vi v� �ehSOv�
- NPDES NO.: IVC 0,02v38 - -
EXPIRATION DATE: 0/13111` q-
REGION:
P&E REQUESTOR:
PRETREATMENT CONTACT:
DATE OF REQUEST:
INDICATE THE STATUS OF PRETREATMENT PROGRAM:
1) THE FACILITY HAS NO SIU'S AND SHOULD NOT HAVE PRETREATMENT LANGUAGE.
' 2) THE FACILITY HAS A PREATREATMENT PROGRAM,
3) ADDITIONAL CONDITIONS REGARDING THE PRETREATMENT PROGRAM ATTACHED.
PERMITTED FLOW:
INDUSTRIAL 4S- SD
DOMESTIC
Pretreatment Unit Staff (Region)
!vD V�jetc��5. 5�-efJl��i'- J A/O ...ClV
5Q DJ TS 5 /V1�3 d) —r. f'4-1 ' OS Gtvre�S /ec�( C'©�� fcf�,.. — J� S�a���o�esper
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,r
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2. v +

LAB SAMPLE NO.(s): 7820E1-2
Sample (s).,-of WASTEWATER
NAM.: JOHN ALT, SR.
ORG :- TOWN OF BENSON
,.ADD* "'170 HANNAH­CREEK ROAD
CSZ FOUR OAKS, NC 27524
of: 3
Marked- - A: 822--03 -INF COMP/3-11-96
C:
Date Received: 3-14-96
Date Reported: 5-8'0-:-96
Telephone [phone]
FAX :--919-8941283­---
-PO/Job No.
PROJECT ID :HEADWORKS"ANALYSI&'
B: 822-03 EFF.,COMP/3--13-,9,6-­-�
D:
Lab Sample
No.=> A:
7820E1 B:
7820E2.C: D.:
CAT. NO.
ANALYSES
UNITS
--
----------------
----------
EW-020 :
-----------------------------------------------
CYANIDE: TOTAL
(mg/L) :
<0.005 :
<0.005
EP-001 :
DIGESTION
:
Yes :.Yes
EM- 03 3. 1:,
ARSENIC-(GFAAS)
(mg/L) :
<0.005 :
<0.005',.:
EM-048
CADMIUM (ICP)
(mg/L)
<0.005 , :
<0.005
:'EM-024
CHROMIUM (ICP)
-,(mg/L)
.<0.002 :
<0.002 .. .....
: EM-029
COPPER (ICP)
(mg/L)
0.0.34
0.031
: EM-082.1:
LEAD (GFAAS)
(mg/L)
0 . P11 :
<0.010
: EM-080.1:
MERCURY (CVAAS)
(mg/L)
<0.0002 :
<0.0002
: EM-042 :
MOLYBDENUM (ICP)
(mg/L)
0.0,13 :
<0.010
EM-028 :
NICKEL (ICP)
(mg/L)
-<O. 010 :
<0.010
EM-034.1:
SELENIUM (GFAAS)
(mg/L)
<0.002 :
<0.002
EM-047 :
SILVER (ICP)
(mg/L)"
0.017 :
.0.006
EM-030 :
ZINC (ICP)
(mg/L)
0.092
0.066
Q.01
Comments: ALL RESULT . S ARE REPORTED ON AN "AS RECEIVED"- BAS
Laboratory Contact For Above Report
Name : Debbie Collins
Title: Head, Water Quality- Section
RLuEovirfm
JUk- 3 1996
-FACILITIES ASSESSMENT UNIT
ve
d7 p ii'
Va &e X,
Manager, EnFviro ental Dept.
----------------- ------
-- ---------------- ---------- SUBMISSION INFO-
Analyst(s): No. Containers: Sample Submission: C-O-C:
Samp Admin: Pickup: Time: Miles: RUSH
------------------------------------------------- -------------------------
Chemical and Microbiological Analyses: Environmental - Industrial Hygiene Agrichemical Foods - Pharmaceuticals

Q
9 FA1R T
Southern Vesting & Research Laboratm-ies, Inc.
3809 Airport Drive [phone] Fax: [phone] Wilson, NC 27896
REPORT OF ANALYSIS
LAB SAMPLE NO.(s): 7999E1-2
of: 3
Date Received:
3-21-96
Sample(s) of WASTEWATER
Date Reported:
5-30-96
NAM : JOHN; ALT , SR.
ORG : TOWN OF BENSON
--..
Telephone :
919--894-2373
- ADD ' - : 7 7 0 ' HANNAH CREEK -,'ROAD--'_ ` -
'
FAX :
919 - 8 9 4 -12 8 3
CSZ FOUR OAKS., -NC 27524
PO/Job No.
PROJECT< ID : HEADWORKS ANALYSIS
Marked A: 822-03_7INF-COMP/3-18-96
B: 822-03-EFF
COMP/3-20-96 _.
C:
<,
D:
Lab Sample_
No.=> A:
7999E1
B: 7999E2 C:
D:
- CAT : NO. ANALYSES
UNITS
--------------------------------------------------------------------------------
: EW-020 : CYANIDE: TOTAL
(mg/L)
<0.005
: <0.00;5
: EP-001 : DIGESTION
Yes
: Yes
.
:-EM-033.1: ARSENIC (GFAAS)
(mg/L)
<0.002
: <0.002
: EM-048 : CADMIUM (ICP)
(mg/L)
<0.002.
: <0.002
: EM-024 :`CHROMIUM-(ICP)
(mg/L) :
<0.005
: <0.005
: EM-029 COPPER (ICP)
(mg/L)-:
0.019
0.017
: EM-082.1: LEAD (GFAAS)
(mg/L) :
<0.010
: <0.010
-
: EM-080.1: MERCURY (CVAAS)
(mg/L) :
<0.0002
: <0.0002
.
: EM-042 : MOLYBDENUM (ICP)
(mg/L) :
<0.01
: <0.01
.
: EM-028 : NICKEL (ICP)
(mg/L) :
<0.01
: <0.01
: EM-034.1: SELENIUM (GFAAS)
(mg/L)
<0.002
: <_0.002
: EM-047 : SILVER (ICP)
(mg/L)
0.018
: <0.005
.
: EM-030 : ZINC (ICP)
(mg/L)
0.128
0.051
Comments: ALL RESULTS ARE REPORTED ON -AN
"AS RECEIVED" BASIS'.
Laboratory Contact For Above Report Revi
Name : Debbie Collins -
Title: -_Head, Water Quality Section 1
and
Environmental Dept.
----- - --------------SUBMISSION INFO(--:�4-----------------------=-==--_
Analyst(s): No. Containers: mple Submission: C-O-C:
Samp Admin: Pickup: Time:. Miles: RUSH :
------------------------------------------------------------------------
Chemical and Microbiological Analyses: Environmental Industrial Hygiene Agrichemical Foods • Pharmaceuticals
tfJ

If
S 9`
P � .
a Southem Testing & Research Laboratofies, Inc.
'� � 3809 Airport Drive [phone] - Fax: [phone] Wilson, NC 27896
9 FA1R '?
SAMPLE No.:
E8167-002
R E P
O R T of A N A L Y S I S
Date Reported: 04/24/96
John Alt Sr.
Town of Benson
770-Hannah Creek Rd.
Phone:[phone] X
Four Oaks NC 27524
Fax: [phone]
P. 0.:
_
Client
Sample -ID: HEADWORKS ANALYSIS
Marks:
822-03-Eff Comp
Collected: 03/27/96 09:00
Matrix:
WASTEWATER
Received: 03/28/96 15:30
Classification:
ENV
CAT No.
ANALYSES
MDL
RESULT
UNITS
EW-020
Cyanide: Total
0.005
ND
mg/L
EW.-.040 .2
-::.Solids c -_Total
2
.329
mg/L
EP-020
Distillation: Cyanide
Yes
EP-001.
-.Digestion (I.CP/FAAS)
Yes
Arsenic (ICP)
.
N
DEM-033
mg/L
EM-048
Cadmium (ICP)
0.002
ND
mg/L
EM-024
Chromium (ICP)
0.005
ND
mg/L
EM-029
Copper (ICP)
0.005
0.039
mg/L
EM-082
Lead (ICP)
0.025
ND
mg/L
EM-080.1
Mercury (CVAAS)
0.0002
ND
mg/L
EM-042
Molybdenum (ICP)
0.010
ND
mg/L.-.
EM-028
Nickel (ICP)
0.010
ND
mg/L
EM-0.34
Selenium (I.CP).
0.1
ND
mg/L
EM-047
Silver (ICP)
0.005
0.006
mg/L 01
EM-030
Zinc (ICP)
0.010
0.064,
mg/L
COMMENTS: ND = Not Detected
Laboratory 'Contact (s): Rev' wed and Approved by:-
Debbie Collins James B. Cox, III, S.
Section Head, Water Quality Manager, Environmental Dept.
Page 2 of 2 E8167R.914 (EHl:V2R07.2) 04/24/96 14:12
Chemical and Microbiological Analyses: Environmental - Industrial Hygiene - Agrichemical • Foods • Pharmaceuticals
5r,

LAB SAMPLE NO.(s).: 8348E1-2
of: 2
Date Received: 4-4-96 -
Sample(s) of WASTEWATER
Date
Reported: 5-30-96
NAM JOHN ALT, SR.
-ORG._:--TOWN•OF_ BENSON . ,-- .
-
Telephone [phone]___
ADD.: 770 HANNAH CREEK ROAD
FAX [phone]
-- CSZ -: FOUR_ -OAKS;- NC. 27524
i
PO/Job - No . - : - -- _
..PROJECT
ID--:HEADWORKS .::ANALYSIS. -
=Marked
As-�822-03-INF-_COMP/4-1-96
B: 822-03-EFF COMP/4-3=96
C:
D:
Lab --Sample
No.=> A:
8348E1-13:
8348E2 C: D:-
CAT . NO.
ANALYSES
UNITS
----------------
--------------------------------------------------
EW-020
CYANIDE: TOTAL
(mg/L) :
<0.005
--------------
: <0.005
• EP-001 :
DIGESTION -
,-_
Yes
Yes ... .. ._ .._...,-....._:. __.._
_
EM-033.1:
ARSENIC (GFAAS)
(mg/L) :
<0.-002
: <0.002 .
:.EM-048
CADMIUM (ICP)
(mg/L) :
<0.005
: <0.005
: EM-024
CHROMIUM (ICP)
(mg/L)
0.006
: <0.0.05
:'EM-029
COPPER-(ICP)
(mg/L)
0.042
0.022
: EM-082.1:
LEAD (GFAAS)
(mg/L)
<0.010
: <0.010
: EM-080.1:
MERCURY (CVAAS)
(mg/L)
0.0003
<0.0002 .
: EM-042
MOLYBDENUM (ICP)
(mg/L)
0.006
0.007
: EM-028
NICKEL (ICP)
(mg/1)
<0.01
<0.01
: EM-034.1:
SELENIUM (GFAAS)
(mg/L)°...<0.002
<0.002 .
: EM-047 :
SILVER (ICP)
(mg/L)
0.018
<0.005
: EM-03.0 :
ZINC (ICP)
(mg/L) :.
0.0.80
0.064
Comments: ALL RESULTS ARE REPORTED ON AN "AS RECEIVED" BASIS.
Laboratory Contact For Above Report Rev wed and App v
Name : Debbie Collins J es B. Cox, II L
Title: Head," Water Quality Section :,M ager; Environmental Dept.
---------------------------SUBMISSION I 0-- -------------------------------
Analyst(s): No. Containers: ample Submission: C-O-C:
Samp Admin: Pickup: Time: -- Miles: RUSH
-------------------------------------------------------------------
Chemical and Microbiological Analyses: Environmental • Industrial Hygiene • Agrichemical • Foods • Pharmaceuticals 0

Hannah Creek r. T
(LNBA Data)
Agency
Station
Parameter
Date
Depth
Result Rmk
LNBA
J5400000
10
8/5/99 11:40
0.32808
25
LNBA
J5400000
10
8/19/9911:10
0.32808
26
LNBA
J5400000
630
8/5/99 11:40
0.32808
0.01 K
LNBA
J5400000
300
8/5/99 11:40
0.32808
0.5 K i
LNBA
J5400000
300
8/19/99 11:10
0.32808
0.5 K c
LNBA
J5400000
625
7/8/99 11:20
0.32808
2.6
LNBA
J5400000
10
7/8/99 11:20
0.32808
26
LNBA
J5400000
10
7/22/9911:20
0.32808
26
LNBA
J5400000
630
7/8/99 11:20
0.32808
0.02 K
LNBA
J5400000
300
7/8/99 11:20
0.32808
0.5 K
LNBA
J5400000
300
7/22/99 11:20
0.32808
0.5 K
LNBA
J5400000
610
8/5/99 11:40
0.32808
0.02
LNBA
J5400000
665
8/5/99 11:40
0.32808
0.71
LNBA
J5400000
625
8/5/99 11:40
0.32808
1.7
LNBA
J5400000
625
6/2/9911:40
0.32808
1
LNBA
J5400000
10
6/23/9911:00
0.32808
20
LNBA
J5400000
10
6/2/9911:40
0.32808
23
LNBA
J5400000
610
6/2/9911:40
0.32808
0.01 K
LNBA
J5400000
610
7/8/99 11:20
0.32808
0.17
LNBA
J5400000
665
7/8/99 11:20
0.32808
0.87
LNBA
J5400000
625
5/4/9913:20
0.32808
1
LNBA
J5400000
300
5/18/9911:35
0.32808
2.4
LNBA
J5400000
300
5/4/9913:20
0.32808
3.4
LNBA
J5400000
10
5/4/9913:20
0.32808
17
LNBA
J5400000
10
5/18/9911:35
0.32808
19
LNBA
J5400000
630
6/2/9911:40
0.32808
0.15
LNBA
J5400000
665
6/2/9911:40
0.32808
0.2
LNBA
J5400000
300
6/23/9911:00
0.32808
0.6
LNBA
J5400000
300
6/2/9911:40
0.32808
0.7
LNBA
J5400000
10
1/10/9511:35
0.49199
5
LNBA
J5400000
300
1/10/9511:35
0.49199
2.6
LNBA
J5400000
610
1/10/95 11:35
0.49199
0.3 K
LNBA
J5400000
625
1/10/9511:35
0.49199
0.55
LNBA
J5400000
630
1 /10/95 11:35
0.49199
0.52
LNBA
J5400000
665
1/10/9511:35
0.49199
0.07
LNBA
J5400000
10
2/2/9512:50
0.49199
5
LNBA
J5400000
300
2/2/9512:50
0.49199
10.2
LNBA
J5400000
610
2/2/95 12:50
0.49199
0.3 K
LNBA
J5400000
625
2/2/9512:50
0.49199
0.37
LNBA
J5400000
630
2/2/9512:50
0.49199
1.19
LNBA
J5400000
665
2/2/9512:50
0.49199
0.07
LNBA
J5400000
10
3/10/9512:05
0.49199
6.5
LNBA
J5400000
300
3/10/9512:05
0.49199
9.8'
LNBA
J5400000
610
3/10/95 12:05
0.49199
0.3 K
LNBA
J5400000
625
3/10/9512:05
0.49199
0.3
LNBA
J5400000
630
3/10/9512:05
0.49199
1.13
LNBA
J5400000
665
3/10/9512:05
0.49199
0.1
LNBA
J5400000
10
4/8/9514:05
0.49199
10
LNBA
J5400000
300
4/8/9514:05
0.49199
7
LNBA
J5400000
610
4/8/95 14:05
0.49199
0.3 K
LNBA
J5400000
625
4/8/9514:05
0.49199
0.46
i%
a/9 5 -
8/91 - r �►�
�04 G/Z % dw LC-S
40
-74
54--10

Hannah Creek
(LNBA Data)
Agency Station
Parameter Date
Depth
Result Rmk
LNBA
J5400000
630
4/8/9514:05
0.49199
0.77
LNBA
J5400000
665
4/8/9514:05
0.49199
0.1
LNBA
J5400000
10
5/8/95 10:45
0.49199
16
LNBA
J5400000
300
5/8/95 10:45
0.49199
6--m8j
LNBA
J5400000
625
3/2/9911:15
0.32808
1.9
LNBA
J5400000
630
3/2/9911:15
0.32808
0.62
LNBA
J5400000
665
3/2/9911:15
0.32808
0.06
LNBA
J5400000
610
5/8/95 10:45
0.49199
0.3 K
LNBA
J5400000
625
5/8/95 10:45
0.49199
0.2 K
LNBA
J5400000
630
5/8/95 10:45
0.49199
0.42
LNBA
J5400000
665
5/8/95 10:45
0.49199
0.14
LNBA
J5400000
10
5/22/9515:25
0.49199
19
LNBA
J5400000
300
5/22/95 15:25
0.49199
7.9
LNBA
J5400000
10
6/7/95 11:55
0.49199
19
LNBA
J5400000
300
6/7/95 11:55
0.49199
LNBA
J5400000
610
6/7/95 11:55
0.49199
0.3 K
LNBA
J5400000
625
6/7/95 11:55
0.49199
0.5 K
LNBA
J5400000
630
6/7/95 11:55
0.49199
0.35
LNBA
J5400000
665
6/7/95 11:55
0.49199
0.24
LNBA
J5400000
10
6/20/9516:00
0.49199
20
LNBA
J5400000
300
6/20/9516:00
0.49199
7.5'
LNBA
J5400000
10
7/12/95 12:20
0.49199
22
LNBA
J5400000
300
7/12/95 12:20
0.49199
2
LNBA
J5400000
610
7/12/95 12:20
0.49199
0.3 K
LNBA
J5400000
625
7/12/95 12:20
0.49199
0.5 K
LNBA
J5400000
630
7/12/95 12:20
0.49199
0.05 K
LNBA
J5400000
665
7/12/95 12:20
0.49199
0.34
LNBA
J5400000
10
7/21/95 2:10
0.49199
25.5
LNBA
J5400000
300
7/21/95 2:10
0.49199
1.2
LNBA
J5400000
10
8/2/9512:25
0.49199
s
25
LNBA
J5400000
300
8/2/9512:25
0.49199
1.8, o
LNBA
J5400000
610
8/2/9512:25
0.49199
0.51
LNBA
J5400000
625
8/2/9512:25
0.49199
1.39
LNBA
J5400000
630
8/2/95 12:25
0.49199
0.05 K
LNBA
J5400000
665
8/2/9512:25
0.49199
0.41
LNBA
J5400000
10
8/16/951:35
0.49199
27
LNBA
J5400000
300
8/16/95 1:35
0.49199
3-8-
LNBA
J5400000
10
9/13/9513:15
0.49199
21
LNBA
J5400000
300
9/13/9513:15
0.49199
�
LNBA
J5400000
610
9/13/95 13:15
0.49199
0.3 K
LNBA
J5400000
625
9/13/9513:15
0.49199
1.46
LNBA
J5400000
630
9/13/9513:15
0.49199
0.06
LNBA
J5400000
665
9/13/9513:15
0.49199
0.8
LNBA
J5400000
10
9/21/95 2:30
0.49199
20
LNBA
J5400000
300
9/21/95 2:30
0.49199
3
LNBA
J5400000
10
10/4/9512:45
0.49199
18
LNBA
J5400000
300
10/4/9512:45
0.49199
LNBA
J5400000
610
10/4/95 12:45
0.49199
0.3 K
LNBA
J5400000
625
10/4/9512:45
0.49199
2.41
LNBA
J5400000
630
10/4/9512:45
0.49199
0.08
LNBA
J5400000
665
10/4/9512:45
0.49199
0.16
2

Hannah Creek
(LNBA Data)
Agency Station
Parameter Date
Depth
Result Rmk
LNBA
J5400000
10
11/10/95 11:25
0.49199
6
LNBA
J5400000
300
11/10/95 11:25
0.49199
7.8 ,
LNBA
J5400000
610
11/10/95 11:25
0.49199
0.3 K
LNBA
J5400000
625
11/10/95 11:25
0.49199
0.6
LNBA
J5400000
630
11/10/95 11:25
0.49199
0.82
LNBA
J5400000
665
11/10/95 11:25
0.49199
0.06
LNBA
J5400000
10
12/6/9511:30
0.49199
8
LNBA
J5400000
300
12/6/9511:30
0.49199
LNBA
J5400000
610
12/6/95 11:30
0.49199
0.3 K
LNBA
J5400000
625
12/6/9511:30
0.49199
0.73
LNBA
J5400000
630
12/6/9511:30
0.49199
1.06
LNBA
J5400000
665
12/6/9511:30
0.49199
0.14
LNBA
J5400000
10
1 /5/96 12:20
0.49199
_2
LNBA
J5400000
300
1/5/9612:20
0.49199
9.6_.
LNBA
J5400000
610
1/5/96 12:20
0.49199
0.3 K
LNBA
J5400000
625
1/5/9612:20
0.49199
0.6
LNBA
J5400000
630
1/5/9612:20
0.49199
1.09
LNBA
J5400000
665
1/5/9612:20
0.49199
0.12
LNBA
J5400000
10
2/8/96 12:20
0.49199
3
LNBA
J5400000
300
2/8/96 12:20
0.49199
11.8
LNBA
J5400000
610
2/8/96 12:20
0.49199
0.3 K
LNBA
J5400000
625
2/8/96 12:20
0.49199
0.5 K
LNBA
J5400000
630
2/8/96 12:20
0.49199
1.17
LNBA
J5400000
665
2/8/96 12:20
0.49199
0.05
LNBA
J5400000
10
3/6/9613:05
0.49199
11
LNBA
J5400000
300
3/6/9613:05
0.49199
8
LNBA
J5400000
610
3/6/96 13:05
0.49199
0.3 K
LNBA
J5400000
625
3/6/9613:05
0.49199
0.56
LNBA
J5400000
630
3/6/9613:05
0.49199
1.27
LNBA
J5400000
665
3/6/9613:05
0.49199
0.15
LNBA
J5400000
10
4/3/96 13:35
0.49199
13
LNBA
J5400000
300
4/3/96 13:35
0.49199
11.2
LNBA
J5400000
10
4/15/9911:50
0.32808
17
LNBA
J5400000
610
4/3/96 13:35
0.49199
0.3 K
LNBA
J5400000
625
4/3/96 13:35
0.49199
0.5 K
LNBA
J5400000
630
4/3/96 13:35
0.49199
3.45
LNBA
J5400000
665
4/3/96 13:35
0.49199
0.1
LNBA
J5400000
10
5/8/9613:55
0.49199
17.5
LNBA
J5400000
300
5/8/9613:55
0.49199
7.8
LNBA
J5400000
610
5/8/96 13:55
0.49199
0.3 K
LNBA
J5400000
625
5/8/9613:55
0.49199
0.59
LNBA
J5400000
630
5/8/9613:55
0.49199
0.33
LNBA
J5400000
665
5/8/9613:55
0.49199
0.12
LNBA
J5400000
10
5/18/9611:40
0.49199
19
LNBA
J5400000
300
5/18/9611:40
0.49199
7
LNBA
J5400000
10
6/5/9610:00
0.49199
19
LNBA
J5400000
300
6/5/9610:00
0.49199
3.8 0
LNBA
J5400000
610
6/5/96 10:00
0.49199
0.3 K
LNBA
J5400000
625
6/5/9610:00
0.49199
0.68
LNBA
J5400000
630
6/5/9610:00
0.49199
0.15
LNBA
J5400000
665
6/5/9610:00
0.49199
0.16
3

Hannah Creek
(LNBA Data)
Agency Station
Parameter Date
Depth
Result Rmk
LNBA
J5400000
10
6/15/9615:20
0.49199
26
LNBA
J5400000
300
6/15/9615:20
0.49199
6.6
LNBA
J5400000
10
7/3/9611:10
0.49199
23.5
LNBA
J5400000
300
7/3/9611:10
0.49199
3.2 W
LNBA
J5400000
610
7/3/96 11:10
0.49199
0.3 K
LNBA
J5400000
625
7/3/9611:10
0.49199
1.14
LNBA
J5400000
630
7/3/9611:10
0.49199
0.27
LNBA
J5400000
665
7/3/9611:10
0.49199
0.23
LNBA
J5400000
10
7/14/9613:50
0.49199
23
LNBA
J5400000
300
7/14/9613:50
0.49199
6.4
LNBA
J5400000
10
8/7/96 12:05
0.49199
21
LNBA
J5400000
300
8/7/96 12:05
0.49199
5.3
LNBA
J5400000
610
8/7/96 12:05
0.49199
0.3 K
LNBA
J5400000
625
8/7/96 12:05
0.49199
0.77
LNBA
J5400000
630
8/7/96 12:05
0.49199
0.05 K
LNBA
J5400000
665
8/7/96 12:05
0.49199
0.29
LNBA
J5400000
10
8/19/96 21:30
0.49199
23
LNBA
J5400000
300
8/19/96 21:30
0.49199
5.6
LNBA
J5400000
10
10/10/9616:45
0.49199
20
LNBA
J5400000
300
10/10/9616:45
0.49199
5.6
LNBA
J5400000
610
10/10/9616:45
0.49199
0.24
LNBA
J5400000
625
10/10/9616:45
0.49199
0.76
LNBA
J5400000
630
10/10/9616:45
0.49199
0.5
LNBA
J5400000
665
10/10/9616:45
0.49199
0.09
LNBA
J5400000
10
11/15/9614:15
0.49199
7.5
LNBA
J5400000
300
11/15/9614:15
0.49199
7.8
LNBA
J5400000
610
11/15/9614:15
0.49199
0.06
LNBA
J5400000
625
11/15/96 14:15
0.49199
0.5 K
LNBA
J5400000
630
11 /15/96 14:15
0.49199
0.16
LNBA
J5400000
665
11 /15/96 14:15
0.49199
0.05 K
LNBA
J5400000
10
12/12/96 13:30
0.49199
13
LNBA
J5400000
300
12/12/96 13:30
0.49199
7.2
LNBA
J5400000
610
12/12/96 13-30
0.49199
0.3 K
LNBA
J5400000
625
12/12/96 13:30
0.49199
0.5 K
LNBA
J5400000
630
12/12/96 13:30
0.49199
0.43
LNBA
J5400000
665
12/12/96 13:30
0.49199
0.05 K
LNBA
J5400000
10
2/5/9713:30
0.49199
11.9
LNBA
J5400000
300
2/5/9713:30
0.49199
7.2
LNBA
J5400000
610
2/5/97 13:30
0.49199
0.05 K
LNBA
J5400000
625
2/5/9713:30
0.49199
0.65
LNBA
J5400000
630
2/5/9713:30
0.49199
0.76
LNBA
J5400000
665
2/5/9713:30
0.49199
0.06
LNBA
J5400000
10
3/5/9714:00
0.49199
15.5
LNBA
J5400000
300
3/5/9714:00
0.49199
8.5
LNBA
J5400000
610
3/5/97 14:00
0.49199
0.05 K
LNBA
J5400000
625
3/5/9714:00
0.49199
0.64
LNBA
J5400000
630
3/5/9714:00
0.49199
0.2
LNBA
J5400000
665
3/5/9714:00
0.49199
0.04
LNBA
J5400000
10
4/2/9711:00
0.49199
12
LNBA
J5400000
300
4/2/9711:00
0.49199
6.2
LNBA
J5400000
610
4/2/97 11:00
0.49199
0.05 K
4

Hannah Creek
(LNBA Data)
Agency
Station
Parameter
Date
Depth
Result Rmk
LNBA
J5400000
625
4/2/97 11:00
0.49199
0.5 K
LNBA
J5400000
630
4/2/9711:00
0.49199
0.57
LNBA
J5400000
665
4/2/9711:00
0.49199
0.04
LNBA
J5400000
10
5/7/9710:40
0.49199
16.6
LNBA
J5400000
300
5/7/9710:40
0.49199
6
LNBA
J5400000
610
5/7/9710:40
0.49199
0.03
LNBA
J5400000
625
5/7/9710:40
0.49199
0.38
LNBA
J5400000
630
5/7/9710:40
0.49199
0.11
LNBA
J5400000
665
5/7/9710:40
0.49199
0.07
LNBA
J5400000
300
4/15/9911:50
0.32808
4.2
LNBA
J5400000
10
5/19/97 9:50
0.49199
19.4
LNBA
J5400000
300
5/19/97 9:50
0.49199
2.4 ►'
LNBA
J5400000
10
6/4/9710:30
0.49199
18.7
LNBA
J5400000
300
6/4/9710:30
0.49199
2.2
LNBA
J5400000
610
6/4/9710:30
0.49199
0.03
LNBA
J5400000
625
6/4/9710:30
0.49199
0.53
LNBA
J5400000
630
6/4/9710:30
0.49199
0.08
LNBA
J5400000
665
6/4/9710:30
0.49199
0.16
LNBA
J5400000
10
6/12/9711:25
0.49199
20.4
LNBA
J5400000
300
6/12/9711:25
0.49199
4 a
LNBA
J5400000
10
7/2/9713:00
0.49199
23.3
LNBA
J5400000
300
7/2/9713:00
0.49199
3.5
LNBA
J5400000
610
7/2/9713:00
0.49199
0.35
LNBA
J5400000
625
7/2/9713:00
0.49199
2.03
LNBA
J5400000
630
7/2/9713:00
0.49199
0.01 K
LNBA
J5400000
665
7/2/9713:00
0.49199
0.55
LNBA
J5400000
10
7/11/9711:05
0.49199
24.1
LNBA
J5400000
300
7/11/97 11:05
0.49199
0.5 K t
LNBA
J5400000
10
8/5/9711:25
0.49199
24.3
LNBA
J5400000
300
8/5/9711:25
0.49199
1.5
LNBA
J5400000
610
8/5/9711:25
0.49199
0.2
LNBA
J5400000
625
8/5/9711:25
0.49199
0.9
LNBA
J5400000
630
8/5/9711:25
0.49199
0.09
LNBA
J5400000
665
8/5/9711:25
0.49199
0.37
LNBA
J5400000
10
8/14/9711:10
0.49199
25.9
LNBA
J5400000
300
8/14/9711:10
0.49199
0.6 c
LNBA
J5400000
10
9/4/9711:45
0.49199
22.4
LNBA
J5400000
300
9/4/9711:45
0.49199
0.8 r
LNBA
J5400000
610
9/4/9711:45
0.49199
0.3
LNBA
J5400000
625
9/4/9711:45
0.49199
1.55
LNBA
J5400000
630
9/4/9711:45
0.49199
0.1
LNBA
J5400000
665
9/4/9711:45
0.49199
0.25
LNBA
J5400000
10
9/17/9712:30
0.49199
22.9
LNBA
J5400000
300
9/17/9712:30
0.49199
1.4
LNBA
J5400000
10
10/8/9710:10
0.49199
18.8
LNBA
J5400000
300
10/8/9710:10
0.49199
1.8
LNBA
J5400000
625
4/15/9911:50
0.32808
0.7
LNBA
J5400000
630
4/15/9911:50
0.32808
0.38
LNBA
J5400000
665
4/15/9911:50
0.32808
0.17
LNBA
J5400000
610
10/8/9710:10
0.49199
0.07
LNBA
J5400000
625
10/8/9710:10
0.49199
0.36
5

Hannah Creek
(LNBA Data)
Agency Station
Parameter Date
Depth
Result Rmk
LNBA
J5400000
630
10/8/9710:10
0.49199
0.08
LNBA
J5400000
665
10/8/9710:10
0.49199
0.12
LNBA
J5400000
10
11/5/9711:45
0.49199
13
LNBA
J5400000
300
11/5/9711:45
0.49199
3.8
LNBA
J5400000
610
11/5/9711:45
0.49199
0.02
LNBA
J5400000
625
11/5/9711:45
0.49199
0.49
LNBA
J5400000
630
11/5/9711:45
0.49199
0.15
LNBA
J5400000
665
11 /5/97 11:45
0.49199
0.07
LNBA
J5400000
10
12/4/9712:35
0.32808
14.9
LNBA
J5400000
300
12/4/9712:35
0.32808
8.9
LNBA
J5400000
610
12/4/9712:35
0.32808
0.01 K
LNBA
J5400000
625
12/4/9712:35
0.32808
0.4
LNBA
J5400000
630
12/4/9712:35
0.32808
0.09
LNBA
J5400000
665
12/4/9712:35
0.32808
0.04
LNBA
J5400000
10
1/6/9814:00
0.32808
13
LNBA
J5400000
300
1/6/9814:00
0.32808
12.2
LNBA
J5400000
610
1/6/9814:00
0.32808
0.15
LNBA
J5400000
625
1/6/9814:00
0.32808
0.1 K
LNBA
J5400000
630
1/6/9814:00
0.32808
0.28
LNBA
J5400000
665
1/6/9814:00
0.32808
0.02
LNBA
J5400000
10
2/9/9811:10
0.32808
7
LNBA
J5400000
300
2/9/9811:10
0.32808
10.5
LNBA
J5400000
610
2/9/9811:10
0.32808
0.02
LNBA
J5400000
625
2/9/9811:10
0.32808
0.3
LNBA
J5400000
630
2/9/9811:10
0.32808
0.57
LNBA
J5400000
665
2/9/9811:10
0.32808
0.09
LNBA
J5400000
10
3/5/9811:55
0.32808
9.8
LNBA
J5400000
300
3/5/9811:55
0.32808
11.4
LNBA
J5400000
610
3/5/9811:55
0.32808
0.02
LNBA
J5400000
625
3/5/9811:55
0.32808
0.6
LNBA
J5400000
630
3/5/9811:55
0.32808
0.43
LNBA
J5400000
665
3/5/9811:55
0.32808
0.01
LNBA
J5400000
10
4/3/9811:20
0.32808
19
LNBA
J5400000
300
4/3/9811:20
0.32808
6.2
LNBA
J5400000
610
4/3/9811:20
0.32808
0.03
LNBA
J5400000
625
4/3/9811:20
0.32808
1.4
LNBA
J5400000
630
4/3/9811:20
0.32808
0.33
LNBA
J5400000
665
4/3/9811:20
0.32808
0.07
LNBA
J5400000
10
5/5/9811:35
0.32808
19
LNBA
J5400000
300
5/5/9811:35
0.32808
5.8
LNBA
J5400000
610
4/15/9911:50
0.32808
0.05
LNBA
J5400000
610
5/4/9913:20
0.32808
0.03
LNBA
J5400000
630
5/4/9913:20
0.32808
0.03
LNBA
J5400000
610
5/5/9811:35
0.32808
0.08
LNBA
J5400000
625
5/5/9811:35
0.32808
0.23
LNBA
J5400000
630
5/5/9811:35
0.32808
0.16
LNBA
J5400000
665
5/5/9811:35
0.32808
0.09
LNBA
J5400000
10
5/19/9811:20
0.32808
22
LNBA
J5400000
300
5/19/9811:20
0.32808
6
LNBA
J5400000
10
6/2/9812:35
0.32808
25
LNBA
J5400000
300
6/2/9812:35
0.32808
7.7
M.

Hannah Creek
(LNBA Data)
Agency Station
Parameter Date
Depth
Result Rmk
LNBA
J5400000
610
6/2/9812:35
0.32808
0.11
LNBA
J5400000
625
6/2/9812:35
0.32808
0.8
LNBA
J5400000
630
6/2/9812:35
0.32808
0.1
LNBA
J5400000
665
6/2/9812:35
0.32808
0.18
LNBA
J5400000
10
6/16/9811:50
0.32808
26
LNBA
J5400000
300
6/16/9811:50
0.32808
4.4
r
LNBA
J5400000
10
7/7/9812:10
0.32808
25
LNBA
J5400000
300
7/7/9812:10
0.32808
1.3
r
LNBA
J5400000
610
7/7/9812:10
0.32808
0.2
LNBA
J5400000
625
7/7/9812:10
0.32808
3.15
LNBA
J5400000
630
7/7/9812:10
0.32808
0.04
LNBA
J5400000
665
7/7/9812:10
0.32808
0.21
LNBA
J5400000
10
7/21/9811:00
0.32808
28
LNBA
J5400000
300
7/21/9811:00
0.32808
4
LNBA
J5400000
10
8/4/9811:50
0.32808
23
LNBA
J5400000
300
8/4/9811:50
0.32808
0.5
6
LNBA
J5400000
610
8/4/9811:50
0.32808
0.05
LNBA
J5400000
625
8/4/9811:50
0.32808
0.6
LNBA
J5400000
630
8/4/9811:50
0.32808
0.01 K
LNBA
J5400000
665
8/4/9811:50
0.32808
0.42
LNBA
J5400000
10
8/18/9811:35
0.32808
25
LNBA
J5400000
300
8/18/98 11:35
0.32808
0.5 K
r
LNBA
J5400000
10
10/13/9812:00
0.32808
24
LNBA
J5400000
300
10/13/9812:00
0.32808
1.2
Q
LNBA
J5400000
610
10/13/9812:00
0.32808
0.3
LNBA
J5400000
625
10/13/9812:00
0.32808
1.28
LNBA
J5400000
630
10/13/9812:00
0.32808
0.11
LNBA
J5400000
665
10/13/9812:00
0.32808
0.88
LNBA
J5400000
10
11/3/9811:00
0.32808
14.5
LNBA
J5400000
300
11/3/9811:00
0.32808
1.7
LNBA
J5400000
610
11/3/9811:00
0.32808
0.05
LNBA
J5400000
665
5/4/9913:20
0.32808
0.09
LNBA
J5400000
625
11/3/9811:00
0.32808
0.5
LNBA
J5400000
630
11/3/9811:00
0.32808
0.15
LNBA
J5400000
665
11/3/9811:00
0.32808
0.08
LNBA
J5400000
10
12/8/9811:40
0.32808
16.5
LNBA
J5400000
300
12/8/9811:40
0.32808
1.5
a
LNBA
J5400000
610
12/8/9811:40
0.32808
0.02
LNBA
J5400000
625
12/8/9811:40
0.32808
0.9
LNBA
J5400000
630
12/8/9811:40
0.32808
0.18
LNBA
J5400000
665
12/8/9811:40
0.32808
0.14
LNBA
J5400000
610
2/4/9911:50
0.32808
0.01 K
LNBA
J5400000
610
1/6/9911:35
0.32808
0.04
LNBA
J5400000
665
1/6/9911:35
0.32808
0.24
LNBA
J5400000
630
1/6/9911:35
0.32808
0.67
LNBA
J5400000
10
1/6/9911:35
0.32808
1.5
LNBA
J5400000
625
1/6/9911:35
0.32808
4
LNBA
J5400000
300
1/6/9911:35
0.32808
8.9
LNBA
J5400000
610
3/2/9911:15
0.32808
0.01 K
LNBA
J5400000
10
3/2/9911:15
0.32808
9
LNBA
J5400000
300
3/2/9911:15
0.32808
6.2
�►
7

Hannah Creek
(LNBA Data)
Agency Station
LNBA J5400000
LNBA J5400000
LNBA J5400000
LNBA J5400000
LNBA J5400000
Parameter Date
665 2/4/9911:50
630 2/4/9911:50
625 2/4/9911:50
300 2/4/9911:50
10 2/4/9911:50
Depth Result Rmk
0.32808 0.05
0.32808 0.36
0.32808 0.6
0.32808 4.6
0.32808 11
L.i

July 21, 1998
The Mr. Charles H. Weaver, Jr.
Wooten NPDES Permits Group
Company NCDENR-DWQ
P.O. Box 29535
Raleigh, North Carolina 27626-0535
Engineering Re: Town of Benson NPDES Permit Renewal Application Additions
Planning NPDES No. NCO020389
Architecture TWC No. 2293
Dear Mr. Weaver:
Pursuant to our conversation of this morning, in reference to additions/corrections for
the recently submitted NPDES renewal application for the Town of Benson, we offer
the following (corresponding to numbers as listed in the NPDES application):
1) Page I-2, item 5 (Facility Location): The street address for the wastewater
treatment plant needs to be modified. The updated street address is as
120 N. Boylan Avenue follows:
Raleigh, NC Benson Wastewater Treatment Plant
27603
770 Hannah Creek Road
Four Oaks, NC 27524
2) Page II-3, item 11 a (Discharge Treatment Description): Several process
units need to be added to the description. The final description shall read as
919-828-0531 follows:
Fax:[phone]
Treatment consists of flow equalization, a bar screen, flow
meter, grit removal, influent pumping station, three (3) aeration
and oxidation ditches, four (4) clarifiers, chemical (alum)
addition for phosphorous removal, tertiary filters, gas chlorination,
dechlorination, and post aeration. Sludge is discharged into a
concrete aerated sludge holding basin for stabilization and storage,
prior to land application.
3) Page H-4, item 11 b (Discharge Treatment Codes): Codes for the additional
treatment units have been added. The final description codes shall read as
follows:
J, S, M, G, SC, APO, N, FSR, PG, Post -air, DA, XD
Please make a note of these items in the application packages and should you have any
questions concerning this matter, please feel free to call.
Sincerely,
THE WOOTEN COMPANY
Since 1936
E. Eric Mills, P.E.
cc: Mr. Keith Langdon, Town of Benson
Mr. Jack Alt, Town of Benson

OF at,
MAYOR
v
>k
DON H. JOHNSON
COMMISSIONERS
NATHAN B. BLACKMON
'PTH CAROB\
RAY G. SMITH
JACK R. LITTLETON
UPRE
KENNITH M.. DUPREE
TOWN OF BENSON
LINDELL NORDAN
P.O. R
J.W. PARRISH, JR.
H
303 EAST CHURCH STREET
NORTH CAROLINA
27504
[phone]
FAX [phone]
March 9, 1998
North Carolina DENR
Kenneth Schuster, P.E.
Dear Mr. Schuster;
TOWN ADMINISTRATOR
KEITH R. LANGDON
TowN CLERK
CAROLYN A. NORDAN, CMC
TAX COLLECTOR
ROSALIE G. WEST
TOWN ATTORNEY
DONALD A. PARKER
This Letter is in response to your letter in February 20, requesting an explanation of the events of January 23. I will address each point in
the following paragraphs.
Your first point was that you could not meet Mr. Alt's request because this would " constitute an illegal discharge". Our permit under
section C allows and permits such an action when there is a danger to property or life. If the walls had failed, two homes and a bridge would have
been imperiled by the on rush of water from the deluge.
. When the overflow of water occurred at the grit chamber, there was a supervisor on top of the filters who was watching the chamber and he
reacted quickly to minimize the overflow. The policy that allows septic haulers to dump into our system has been modified to eliminate any extra
flows into the plant during times of extreme weather.
We do no have any written or oral recommendations concerning the freeboard depth our lagoons. We have relied upon the operators'
judgement as to what was suitable working depth. In this situation, we had rains that were equivalent to those during hurricane fran and coupled with
high flows into the plant there was no way to pump from the lagoons into plant and lower the levels in the lagoons to protect the integrity of the
walls.
Mr. Alt has sealed the valves and they have not been opened since Hurricane Fran as per your departments' instruction. There is a section
of the lagoon wall that had some water overflow. This was inspected and tested and no problems were found. The section of the wall that this occurs
at is lower than any other section. Years ago this part of the wall was used by a construction company to store dirt from excavations at the plant.
When they remove the dirt from the area for back filling they removed a few inches too much and this section the wall be brought back to its original
height. We are in the process of adding suitable dirt to this low area to prevent any overflows in future. This area should be corrected__ hv_, th_e week
ending March 13, 1998.
The town is currently pursuing an I and I elimination strategy that is estimated to cost $950,000.00 and will impact about 20% of our
system. It is evident that we have problems with this system and I will require a lot time and money to repair. The town has pursued a conservative
strategy of having the plant rerated in order to no over -burden our citizens with debt. We started this process some 18 months and have been
repeatedly held up by your department. This re -rating would be sufficient to handle the needs of capacity for our plant for 3-5 years. This would
allow the town time to retire its present bond debt and be in a position to finance a full expansion without a severe impact upon its ratepayers. We
are ready to begin the planning process but; again, your department has held up our engineers due to an inability to provide us with data concerning
\nitrogen removal requirements for our plant. I would say that HB 515 mandates a 301/6 reduction of nitrogen from 1995 levels and our plant has
already achieved more than that and is working with the LNRB to make even more reductions.
_ T
----------------
I ope at t 's letter explains our situation and if you need further information please contact Town Manager Keith R. Langdon or me at
[phone].
Sincerely,
j
Abn�hnson
Mayor '
DHJ/cros
schuster-ncdenr

To: Permits and Engineering Unit
Water Quality Section
Attention:
NPDES STAFF REPORT AND RECOMMENDATION
County Johnston
Permit No. NC�10020389 /,�.j,346e�e4!
PART I - GENERAL INFORMATION N
N MAY 1999 W
1. Facility and Address : Town of Benson WWTP N RECEIVED,
Post Office Box 69 N Watet WRY cn
Benson, NC 27504 t9c, Ptatteatment cp" G ✓� a, i' Q'
2. Date of :January 29, 1999
�tZLZO'L6
3. Report Prepared by: S. Mitchell
4. Persons Contacted and Telephone Number:Mr. John Alt
919-894-2373
S. Directions to Site:Highway 50 So thru Benson, left on
SR 1143, left on SR 1141, left on entrance road before I 95
6. Discharge Point(s), List for all discharge points:
Latitude: S° 3'
Longitude: 7803 0 ' 3 0"
U.S. Quad No.F 24 NE Quad Name:Benson
7. Site size and expansion area consistent with
application ? _XX_ Yes No If No, explain:
8. Topography (relationship to flood plain included):Flat
9. Location of nearest dwelling:greater than 100 meteres
10. Receiving stream or affected surface waters:
Hannah Creek
a. Classification:C NSW
b. River Basin and Subbasin No.: 03-04-04 NEU
C. Describe receiving stream features and
pertinent downstream uses:Swamp

PART II - DESCRIPTION OF DISCHARGE AND TREATMENT WORKS
C '
1. a. Volume of Wastewater.to be permitted:-A--5—MGD
b. What is the current permitted capacity of the Waste
Water Treatment facility?1.5 MGD
C. Actual treatment capacity of the current facility
(current design capacity)?1.5 MGD
d. Please provide a description of existing or
substantially constructed wastewater treatment facilities:
Mechanical bar scree and grit removal, manual bar screen
with Parschall flume, splitter box, 3 oxidation ditches, 4
clarifiers, tertiary filters, chlorine disinfection and
con/tact chamber, aerated sludge lagoon, and 2 stabilization
lagoons.
e. Please provide a description of proposed wastewater
treatment facilities:Proposed system to include enhanced
nitrogen removal. (See SOC)
f. Possible toxic impacts to surface waters:Chlorine.
2. Residuals handling and utilization/disposal scheme:As
necessary and in approved manner under Permit WQ0012514.
3. Treatment plant classification:Class 3
4. SIC Code(s):4952
Wastewater Codes
Primary _01_ 78
Main Treatment Unit Code: 101 3
PART III - OTHER PERTINENT INFORMATION
1. Is this facility being constructed with Construction Grant
Funds or are any public monies involved. (municipals only)?No
2. Special monitoring or limitations (including toxicity)
requests:None
3. Alternative Analysis Evaluation: Has the facility evaluated
all of the non -discharge options available. Please provide
regional perspective for each option evaluated.
Spray Irrigation:No land available
Connection to Regional Sewer System:N/A
Subsurface:N/A
Other disposal options:No alternatives available.
5. Other Special Items:

PART IV - EVALUATION AND RECOMMENDATIONS
The most recent inspection of this facility indicated complinace
with the terms �d regulations contained in the discharge permit.
The plant appeared to be well maintained and in good operational
condition. Therefore the Raleigh Regional Office recommends the
reissuance of the discharge permit.
TDate
Signature of report preparer
TIC61
I��_ Date Water Quality Regional Supervisor

III ` / >/ ,• � 1 _ •. @ 'ca
J 263 •rye` _ ^' / `'•./ 9 :!' : I --'
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S
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179
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724 725 726000m.E...
• •32'30" 'moo
ROAD CLASSIFICATION L
Light -duty road• hard or
° v
MILE Primary highway, s� .s
hard surface. improved surface s4 s
Secondary highway, — Unimproved road s�o
hard surface — --- '
Interstate Route U. S. Route State Route
a-

Fd�R M2
The October 24, 1997 `
Wooten Mr. Don Safrit br
Company Assistant Chief POINT SOURCE BRANCH
Technical Support Branch
Engineering NCDEHNR-DWQP.O. Box 29535
Planning Raleigh, N.C. 27626-0535
Architecture Re: Speculative Limits Request
Benson Wastewater Treatment Plant
NPDES Permit No. NCO020389
TWC No. 2293
Dear Mr. Safrit:
We are writing on behalf of the Town of Benson to request speculative limits for 2
sites of discharge for the existing Benson Wastewater Treatment Plant. A map
showing the existing and proposed discharge location is enclosed. This plant,
120 N. Boylan Avenue which operates under NPDES Permit No. NC0026051, is permitted at an average
Raleigh, NC daily flow of 1.5 million gallons per day GD and discharges to Hannah Creek
27603 y g p y� ) g
in the Neuse River Basin (labeled "Existing Discharge Point"). The other proposed
location for discharge is in Mingo Swamp, which is in the Cape Fear River Basin
(labeled "Proposed Discharge Point").
Speculative limits are requested for a flow of 2.0 MGD at both locations. On
919 828 0531 Mingo Swamp, if the Division has any recommendations as to alternative discharge
points in the vicinity, we would entertain and investigate these alternative locations.
We asked Mr. Curtis Weaver of the USGS to provide background flow information
at the Mingo Swamp location. Mr. Weaver informed us that his office had flow
data for a point on Mingo Swamp, southeast of Dunn. Giving us the drainage area
of our proposed discharge location and the Dunn -Mingo Swamp location, he
suggested that we proportion the given flow information to back out flow estimates
for our desired point. We have done that on the following page.
If you have any questions or require any additional information, please contact us at
828-0531.
Sincerely,
THE WOOTEN COMPANY
E. Eric Mills
Enclosures
Since 1936
cc: Mr. Keith Langdon, Town of Benson (w/enclosures)

STREAMFLOW ESTIMATES FOR PROPOSED MINGO SWAMP. DISCHARGE
Town of Benson, N.C.
In order to estimate streamflow data for our proposed discharge location on Mingo'Swamp, data
was acquired from an USGS stream gaging station just southeast of Dunn, NC. By using the
proportion of the drainage area of the known data and the drainage area of our proposed discharge
location, the streamflow data for the proposed location was approximated. This method of
approximation was suggested to us by Mr. Curtis Weaver of the USGS. Given data from the
Dunn -Mingo Swamp location and approximated data from our proposed discharge location are as
follows:
Given Data from USGS
Gaging Station Name:
Gaging Station Number:
Gaging Station Location:
Drainage Area at Location:
# Measurements Made:
Average Flow:
Annual or summer 7Q10 Flow:
Winter 7Q10 Flow:
Annual 30Q2 Flow:
Annual 7Q2 Flow:
Mingo Swamp near Dunn
02106760
Intersection of Mingo Swamp and Highway 421,
southeast of Dunn
50.4 square miles
50 (1955-1985)
50.4 cfs (runoff is 1.0 cfs per mil)
0.0 cfs
1.6 cfs (Nov. - March)
3.3 cfs
0.2 cfs
Flow Data for Proposed Discharge Location
Proposed Location Name: Mingo Swamp near Benson
Proposed Location: Intersection of Mingo Swamp and SR 1102 (Johnson
County side) and SR 1812 (Harnett County side)
Drainage Area at Location: 14.3 square miles
• Using the two (2) drainage areas given, a proportioning factor was derived:
14.3 mil _ 50.4 mil = 0.2837
• This factor was multiplied by the given flow data to approximate the flow data at the
proposed location as follows:
Average Flow: 14.3 cfs
Annual or summer 7Q10 Flow: 0.0 cfs
Winter 7Q10 Flow: 0.454 cfs (Nov. - March)
Annual 30Q2 Flow: 0.936 cfs
Annual 7Q2 Flow: 0.057 cfs

\ I) J
­�) �• :` \ � - , ..'' 11�•5 <� � /.._•� I/ `;'-- -i Lone lI S v4age ( --
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if EXISTING
If
11/I \ if
DISCHARGE
-c' .�..;�: 2� POINT
(1 r �OIL
.�w� (� • —_ S i . I ( ) l '
II ,, �;..•�
Lj
°ll :✓�•.,�.. •."�'�\.� �i,. f<• Ile=ell_"_= Ce_m /f // •1.l�r�a��l� ��_'uf II' :/�
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`Avg- Cq';1
. - , _ �' ,,,,,,iii �• -<. 223
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,1 Tank',' 1 ; I '..\\ •: 726000m.E.
242
• 'll 301j •�; ��•�
I' I �� '; ( '�� �� r•95 Benson so ROAD CLASSIFICATION
I Primary, hi hwa
2441 I" / I /�;' ^ \ ---- _______ Y g Y• Light -duty road, hard or
hard surface..,... improved,surface ..
I t
Secondary highway
1 I� l• , r• ; • �, ,.:, �11)ge
l� hard surface .................. —_, Unimproved road.........______
�_3 C� State Rout,
Interstate Route U. S. Route
223
I it ` / i r ti ,•�
1 Water.
09 1 , Tank
e
` 20o t ll Glove it
L• \ i .-; . � � �� LOCATION MAP
Joh, Benson Wastewater Treatment Plant
-'1'sT° ` ��� I, Benson, NC
NPDES No. NC0020389
i ��' co° (/I �r.'• �l USGS Map: Benson & Dunn, NC
Scale: 1"-2000'
TernJ102
(1709)
21
%Cem ✓'„ o
240 ^ PROPOSED l
11 , DISCHARGE V1..
POINT

'i_' ..."
State of North Carolina
Department of Environment,
Health and Natural Resources
Division of Water Quality
James B. Hunt, Jr., Governor SEP
Wayne McDevitt, Secretary
A. Preston Howard, Jr., P.E., Director POINT SOURC
CERTIFIED MAIL
RETURN RECEIPT REQUESTED
The Honorable Don H. Johnson
Town of Benson
P.O.. Box 69
303 East Church Street
Benson, NC 28694
Subject:
Dear Mayor Johnson:
J4 J:
=HNR
AAA lo4e_,
ez � ce,&-e f
em
�✓-/ ,0,
Lifting of Sewer Line Moratorium
Town of Benson
NPDES Permit No. NCO020389
Johnston County
On June 12, 1997 a moratorium on the issuance of sewer line permits was placed on the
Town of Benson per the authority of 15A NCAC 2H .0223, which specifies that prior to
exceeding 80% of their hydraulic treatment capacity, facilities must submit an approvable
engineering evaluation of their future wastewater needs before permits for sewer line extensions
may be issued. Monitoring data submitted by the Town showed the subject wastewater treatment
plant operated at 89.53% of its treatment capacity during 1996.
I have reviewed the Town of Benson's letter of July 24, 1997, requesting to have the
sewer moratorium lifted along with the "Future Wastewater Treatment Plan Including Wastewater
Disposal Alternative Analysis," prepared by the Wooten Company. The report presented the
Town's "two prong" strategy in addressing future wastewater treatment needs and compliance with
15A NCAC 2H .0223, namely the reduction of inflow and infiltration to the collection system and
the re -rating of the existing wastewater treatment plant to a higher design capacity. While a final
determination on the latter portion of this strategy is still under review by Division staff, I have
determined that by submitting this report, the Town has complied with the terms of 15A NCAC 2H
.0223(l).
In light of these findings, I hereby remove the moratorium on the issuance of sewer line
permits placed on the Town of Benson. The Town is reminded that prior to the facility exceeding
90% of its permitted hydraulic capacity, approvable plans and specifications, including a
construction schedule, must be submitted to the Division in order to remain in compliance with the
terms of 15A NCAC 2H .0223. Compliance will be judged based upon the facility's average flow
of calendar year 1997 and subsequent calendar years. Should the average flow for any calendar
year exceed 90% of permitted hydraulic capacity without the Town having first submitted the
required plans and specifications, the sewer line moratorium will again be imposed.
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

If you have any questions about this letter, please do not hesitate to contact Judy Garrett,
Water Quality Regional Supervisor for our Raleigh Regional Office at [phone], extension
252 or Bob Sledge of our Central Office staff, at [phone], extension 233.
Sincerely,
A. Preston Howar Tr. P.E.
cc: Steve Tedder
Ken Schuster
Don Safrit
Kim Colson
Bob Sledge

State of North Carolina
Department of Environment,
.Health and Natural Resources
Division of Water Quality
James B. Hunt, Jr., Governor
Wayne McDevitt, Secretary
A. Preston Howard, Jr., P.E., Director
September 16, 1.997
Mayor Don H. Johnson
Town of Benson
Post Office Box 69
Benson, North Carolina 27504
Subject: Permit Application Return
Return Number 889
Permit No. NCO020389
Town of Benson WWTP
Johnston County
Dear Mayor Johnson:
POINT SOURCE BRANCH
A review of the NPDES Permit Application (Standard Form A) and the report titled "Future
Wastewater Treatment Plan Including Wastewater Disposal Alternative Analysis" indicated that the
report does not include all of the information required for the Division to accurately review the re -
rating request and.the alternatives analysis provided is insufficient. Therefore, the application
package is being returned as incomplete.
This letter is divided into two separate comment sections. The first section covers the
deficiencies identified during the Engineering Alternatives Analysis review. The second section
identifies the deficiencies in the re -rating request and potential obstacles for approving this request.
Engineering Alternatives Analysis Review
In addition to requesting a flow expansion, a comprehensive Engineering Alternatives
Analysis must be prepared to study all possible discharge options. Based on the findings of the
Division staff, the Division requires that more information be provided regarding possible
alternatives to discharge. It is the Division's mandate to permit the most environmentally sound
wastewater treatment system of the reasonably cost effective alternatives. Subsurface or irrigation
disposal systems are typically considered to be more environmentally sound alternatives than
discharges to surface waters. The following issues must be addressed prior to resubmitting the
Engineering Alternatives Analysis for Division review:
• The report titled "Wastewater Treatment Plan Including Wastewater Disposal
Alternative Analysis" discusses the fact that the Town of Benson is experiencing, and
wishes to continue experiencing, a moderate growth rate. The report does not provide
documentation that a study was performed in reference to projected growth for the area.
The Engineering Alternatives Analysis must provide justification for the requested flow
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

�f 0
Permit Application Return
Return Number 889
Permit No. NCO020389
Town of Benson WWTP
Page 2 of 3
increase. A detailed study should be performed to project growth (i.e., perform a 20-
year projection on population and commercial/industrial growth).
• An Engineering Alternatives Analysis also requires the comparison of present worth
costs for each technically feasible alternative. ' Resubmittal of this application must
include a present worth cost analysis to. support the claim that the direct discharge is the
only viable option.
• The Engineering Alternatives Analysis stated that surface water discharge can be
continued without any additional capital costs. The Division disagrees with this
statement for two reasons. First, House Bill 515 was recently approved which requires
facilities that discharge to Nutrient Sensitive Waters (NSW) in the Neuse River Basin to
meet a total nitrogen limit of 5.5 mg/l. In addition, the Neuse River NSW Management
Strategy is currently being reevaluated. The modified strategy has not been finalized,
but may include more restrictive limits than House Bi11515 for any expanding
discharge. It is the Division's understanding that the current facility does not have
nitrogen removal capabilities. In response to these additional requirements, information
should be provided in reference to the capital and the operation and maintenance costs
required to upgrade the facility for nitrogen removal.
In addition, the Engineering Alternatives Analysis report stated that if nutrient removal
capabilities can not be achieved with minimal capital costs, then the treated effluent can
be discharged to Mingo Swamp in the Cape Fear River Basin. A more detailed
discussion of this alternative is required.
As outlined in the Division's Guidance for Evaluation of Wastewater Disposal
Alternatives (copy attached), the analysis of subsurface and irrigation disposal systems
may require a report based on a site investigation from a soil scientist. However, a
screening method may be used to gather and interpret preliminary data without
performing a site investigation. First use county soil maps to identify on -site soils.
Using this soils characterization, determine best case loading rates. Then perform a
present value of cost analysis. If the present value for -a non -discharge alternative is
less than a discharge system, then a more detailed report from a soils scientist must be
performed based on a site investigation. This document should include the following:
- A copy of field notes and boring log information.
- A soils site map overlain on a topographic map.
- Description of soils characteristics to include texture, structure, soil wetness and
mineralogy.
- Characterization of the depth of soil to 48" or to a restrictive horizon, and
Soil loading rate recommendations and land area requirements.
If the present value for a non -discharge alternative is greater than 15% higher than a
discharge system, no further information is necessary.
• In reference to water reuse, please provide more information in reference to the large
water using industry referenced in the alternatives analysis report. It was stated that
this facility produces pharmaceutical grade materials, and any water of lesser quality
than potable water is likely to prove objectionable for use. Please provide

Permit Application Return
Return Number 889
Permit No. NC0020389
Town of Benson WWTP
Page 3 of 3
documentation that this facility would reject the use of recycled water, even for non -
process water use such as lawn irrigation or cooling water use.
Re -rating Request
The re -rating request is considered a major modification based on the fact that the additional
flow will be considered "new flow." Please be aware that any increase in flow to the Neuse River
Basin will most likely initiate significant public interest. The public may request that a hearing be
scheduled in reference to the proposed expansion. In addition, the request may take in excess of
six months to issue. For example, two municipalities in the Neuse River Basin recently requested
expansions. One facility requested an expansion in June of 1996 and the other facility submitted
its request in August of 1996. Public hearings were held for both facilities in early July 1997.
The first step the Town of Benson should take is to submit a request for speculative limits
based on the expanded flow. This is a free service offered by the Division for municipalities.
Upon receipt of this request, the Division will prepare a wasteload allocation to study the effects
of the proposed discharge on the receiving stream. New effluent limitations will be developed
based on the assimilative capacity of the receiving stream. Speculative limits, based on the
expanded flow, must be developed and incorporated into a modified NPDES permit prior to
requesting an Authorization to Construct. In other words, the existing permit must be modified to
include limits for the "new flow" prior to requesting a re -rating of the facility.
The Division would like to suggest that a meeting be scheduled to discuss the issues that
were addressed in this letter. Should you have any questions or if you would like to schedule a
meeting, please do not hesitate to contact Jeff Myhra at [phone], extension 597.
Sincerely,
A. Preston Howard, Jr., P.E.
cc: -C�
Raleigh Regional Office, Water Quality Section
NPDES Unit, Jeff Myhra
Buck Kennedy, The Wooten Company

July 24, 1997
The
Wooten Mr. David A. Goodrich
NPDES Group Supervisor
Company NPDES Permits Group
NCDEHNR-DWQ
P.O. Box 29535
Engineering Raleigh, NC 27626-0535
Planning
Re: NPDES Permit Modification
Architecture Demonstration of Future Wastewater Treatment Capacities
_ NPDES No. NCO020389
Town of Benson
Johnston County
TWC # 2293
Dear Mr. Goodrich:
Per your request letter dated April 25, 1997 and the request letter from Mr. Steve
120 N. Boylan Avenue W. Tedder dated June 12, 1997, we are hereby forwarding the requested items in
Raleigh, NC regards to the modification of NPDES Permit No. NC0020389. This modification
27603 is requested to increase the plant's flow rating from 1.5 MGD to 1.732 MGD,
which will allow time for the Town's inflow and infiltration rehabilitation program
to take effect. The following items are enclosed:
1) Three (3) copies of the executed NPDES Permit Application (Standard
919-828-0531 Form A).
2) A check in the amount of $400, made out to NCDEHNR, to cover the
permit modification fee.
3) Three (3) copies of the Future Wastewater Treatment Plan Including
Wastewater Disposal Alternative Analysis. This plan is written as
requested in your letter and Mr. Tedder's letter.
We trust that this submittal covers all requirements set forth by your department.
However, if you have any questions or require any additional information, please
contact us.
Sincerely,
THE WOOTEN COMPANY
E. Eric Mills
Enclosures
Since 1936 cc: Mr. Keith Langdon, Town of Benson (w/enclosures)
NCDEHNR-DWQ Facility Assessment Unit (w/enclosures)
Cl

TOWN OF BENSON
NORTH CAROLINA
FUTURE WASTEWATER TREATMENT PLAN
WASTEWATER DISPOSAL ALTERNATIVE
JuLY 1997
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EVERETTE L. CHAMBLISS, P.E.
THE WOOTEN COMPANY
Engineering - Architecture - Planning
120 North Boylan Avenue
Raleigh, North Carolina 27603
INCLUDING
ANALYSIS

----
TOWN OF BENSON
NORTH CAROLINA
FUTURE WASTEWATER TREATMENT PLAN INCLUDING
WASTEWATER DISPOSAL ALTERNATIVE ANALYSIS
Jui,Y 1997
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EVERETTE L. CHAMBLISS, P.E.
THE WOOTEN COMPANY
Engineering - Architecture - Planning
120 North Boylan Avenue
Raleigh, North Carolina 27603

Table of Content
General Information ..... .::......... ......... - ...
1.1 Facility and Analysis Information ................................
1
1.2 Project Description and Flow Projections ...........................
1
1.3 Existing Units .............................................
2
1.4 Project Phase .............................................
6
2.0 Evaluation of Disposal Alternatives ....................................
7
2.1 Connection to a Sewer Collection System ...........................
7
2.2 Land Based Disposal ........................................
7
2.3 Wastewater Reuse ..........................................
8
2.4 Surface Water Discharge .......... . ...........................
9
2.5 Conclusions ...............................................
9
3.0 Summary.....................................................10
I
U

1.0 GENERAL INFORMATION
1.1 Facility and Analysis Information
Facility Name:
County:
Facility Address:
Facility Telephone Number:
Report Preparer's Name:
Benson Wastewater Treatment Facility
Johnston County
Off of SR 1171, South of I-95
[phone]
Everette L. Chambliss, P.E.
Report Preparer's Address: The Wooten Company
120 North Boylan Avenue
Raleigh, NC 27603
Report Preparer's Telephone Number: [phone]
1.2 Project Description and Flow Projections
The Town of Benson's existing wastewater treatment plant (WWTP) has a currently
permitted capacity of 1.5 million gallons per day (MGD). The average flow calculated for calendar
year 1996 was 1.343 MGD, which represents 89.53% of the existing permitted capacity. While the
average flow is distorted due to an exceptionally wet year, more ordinary flow conditions saw
average flows approaching and at tunes exceeding 80% of the design capacity. The Town of
Benson is experiencing, and wishes to continue experiencing, a moderate growth rate. In order to
accommodate this growth rate without wastewater treatment capacity constraints, the Town has
adopted a two prong strategy. This strategy has been developed in consideration of two factors
s
unique to the Benson situation. These are: (1) the fact that a low strength industrial discharge is a
major component of the Town's wastewater stream, resulting in the Town having ample organic
load reserve capacity, and; (2) the fact that infiltration and inflow account for much of the peak 30
day loading experienced by the Town's treatment plant. The first prong of the Town's strategy is
to aggressively pursue infiltration and inflow correction, with the goal of eliminating infiltration
and inflow sources at a rate at least equal to the rate at which growth increases domestic,
commercial, and light and/or dry industrial wastewater flows. This prong of the strategy is
expected to result in no net increase in wastewater flow rates over the next 5 to 10 years, and
possibly even a decrease in flow rates. The second prong of the strategy is to provide some
additional permitted treatment capacity to provide the Town some cushion for accommodating
growth while its infiltration and inflow rehabilitation efforts are getting underway.
A report entitled "Wastewater Treatment Plant Capacity Evaluation" was performed in
December 1996 to determine how much of a reserve capacity is available at the existing plant. That
1

study concluded that even the most limiting treatment unit, the final clarifiers, could perform
-- - ---adequately at an -average daily -flow-of-1:732--MGD. Therefore, it was concluded that-the--plant-can- - - -
operate as a 1.732 MGD tertiary treatment facility and a request has been made for a NPDES
permit flow limit increase to that level. This will provide the Town with 0.232 MGD of additional
treatment capacity while it works on recovering more capacity through an inflow and infiltration
abatement program.
1.3 Existing Units
Existing units, which would remain- in use with an increase in permitted flow, are described
as follows:
Design Population
3,924
Design Waste Loadings, mg/L
BODS (Bio-Chemical Oxygen Demand, 5 day 20' C)
2500 lbs/day
TSS (Total Suspended Solids)
2500 lbs/day
NH3-N (Ammonia Nitrogen)
2501bs/day
Phosphorous
100 lbs/day
Bar Screens
Mechanical:
Number of units
1
Design flows, ADF, mgd
1.50
PDF, mgd
3.75
Channel width, ft
2
Channel depth, ft
5
Motor horsepower, hp
0.5
Unit power control
Time Clock
Maximum raki lift capacity, lb
462.0
Manual:
Number .of units
1
Channel width, ft
_ 1.5.
Channel depth, ft
2
Unit capacity, mgd
1.65
Grit Chamber
Number of units
1
Length, ft
17
Width, ft
1.25
Average water depth, ft
1.50
Detention time at peak flow, min
0.30
Velocity at peak flow, ft/sec
1.36
Surface overflow rate at peak flow, mgd/sq ft
0.077
Method of grit removal
Mechanical
Comminutor
Number of units
1
Unit size, in -
15
Unit capacity, mgd
2.4
Size of drive unit, hp
0.75
2

Parshall Flume (for -flow measuring)
_ _ Number of units, 9-inch size 1
Aeration Tanks (Oxidation Ditches)
Number of units
3
Liquid depth, ft
5
Unit Volume, mil gal
0.618
Total Volume, mil gal
1.854
Detention time, average hr
30
BOD5 to aeration tanks, lb/day, average
2,500
Organic loadings to tanks, lb BOD5/1000 ft3, average
10
MLVSS concentration, mg/L
2,200
F/M ratio, lb BOD5/lb MLVSS
0.09
MCRT or SRT, days (@ 10° C, Yn=0.65, BODR=98%)
27
Sludge recycle ratio
1:1
Aeration Facilities for Aeration Tanks
Type of aeration
Mechanical, brush type
Number of aerators, 27 1 in x 10 ft long brush
rotor with 7.5 hp drive unit, each/tank
4
Total number of brush aerators
12
Total horsepower provided, hp
90
Aerator capacity at 6-in immersion, lb 02/hr/ft of rotor
1.74
Total aeration capacity, lb 02/hr
208.80
Total oxygenation capacity, lb 02/lb BODr, average
2.00
Secondary Clarifiers
Number of units, 35 ft diam x 12 ft SWD
2
Unit Volume, gal
86,359
Number of units, 35 ft diam x 10 ft SWD
2
Unit Volume, gal;
71,966
Total Volume, gah
316,650
Detention time at average flow, his
5.07
Unit surface area, sq ft
962
Total surface area, sq ft
3,848
Surface overflow rate, gpd/sq ft
390.
Unit weir length, ft
110
Total weir length, ft
440
Weir overflow rate, gpd/lf
3,410
Type of sludge removal
Pump
Filters
Number of filters, 10 ft x 12 ft
5
Total surface area, sq ft
600
Filtration rate at average daily flow, gpm/sq ft
1.74
Filtration rate at peak daily flow, gpm/sq ft
4.34
Maximum wash rate at 20' C, gpm/sq ft
15.0
Filter Media
Anthracite Medium:

2 ft 3 inch depth of the media. Particle sizes ranging from 1.2 mm to 1.6 mm, with
a maximum uniformity coefficient of 1.4 and not more than 10% by weight being
no more than 1.2 m- Anthracite has aspecific-gravity of 1:57.
Silica Medium:
12-inch depth of the media. Particle sizes ranging from 0.50 mm, with a maximum
uniformity coefficient of 1.6 and not more than 10% by weight being smaller than
0.50 mm. the specific gravity of sand is 2.50.
Gravel Medium:
13-inch depth of the media consisting of..
4-inch 1/8" x No. 16 mesh
3-inch 1/8" x 3/8"
3-inch 3/8" x 1"
3-inch 5/8" x 1"
Underdrain system Wheeler bottom type
Caustic Feed System (for alkalinity and pH Control)
Total lime storage capacity, cu ft 1,800
Number of feed pumps 2
Feed rate, gal/hr 0 - 0.5
Alum Feed System (for phosphorus removal)
Number of storage tanks, 12'-0" ID x 18'-6" 2
Unit capacity, gal 15,000
Total capacity,. gal 30,000
Number of feed pumps 2
Feed rate, gal/hr at 150 psig back pressure 50
Motor horsepower, hp 1
Chlorination System
Chlorine Contact Tanks
Number of tanks 23'-6" x 8' - 8" x 6' - 6" SWD 2
Unit volume, gal 8,593.5
Total volume, "gal 17,187
Detention time at average daily flow, min. 16.5
Chlorine Feed System
Number of chlorinators 2
Chlorine feed rate, lb/day 20 - 200
Number of one ton cylinders 4
Filter Backwash Clear Water Storage
Number of tanks - 18'-8" x 18'-0" x 6'-6"/11'-3" x 9'-10" x 5'-0" 1
Total volume, gal 20,475
Post Aeration
Number of units 18'-6" x 18'-0" x 6'-6" 1
Total volume, gal 16,190
Detention time at average daily flow, min. 15.5
Type of aeration Submerged self -aspirating type
Number of aerators, 7.5 hp 1
Aerator capacity, CWTR at 41 cfm air flow and STP in lb 02/hr 26
Dechlorination System
Solution type
4
Sodium sulfite

Number of metering pumps
2
Capacity, gph
—----------
-- -- - -
0 to 1.5 --
— - --
T -^^ Solution tank size, gal
250
Aerated Sludge Holding Lagoon (for
sludge stabilization, disposal)
Number of lagoons
1
Size of lagoon:
Area at water surface, sq ft
191 ft x 299 ft = 57,110
Area at bottom surface, sq ft
166 ft x 274 ft = 45,310
Side slopes
1.5:1
Liquid depth, ft
8.5
Total volume, gal
3,080,220
Stabilization Lagoons (for equalization of influent flow & filter backwash waste)
Number of lagoons
2
Size of lagoon
Lar es rLai!oon
Smaller lagoon
Area at water surface 315' x 575'
= 181,125 sq ft.
1/2 (385+265)x795=258,375 sq ft
Area at bottom 300' x 560' = 168,000 sq ft
1/2 (370+250)x780=241,800 sq ft
Slide Slopes
2.5:1-
Liquid depth
3.0 ft
Volume of each lagoon, gal
3,844,800
5,611,960
Total volume, gal
9,456,760
Pumps:.
Pump Type
No. hp/each unit TDH
Design Capacity*
Screw Pumps
1 5
7 ft
1,750 gpm
Screw Pumps
2 3
7 ft
1,370 gpm
Filter Lift Pumps-
3 15
34 ft
1,300 gpm
Sludge .Recirculation Pumps
2 10
17 ft
1,050 gpm
Sludge Waste Pumps
a
1 1.5
10 ft
100 gpm
Scum Pumps
2 1.5
10 ft
100 gpm
Filter Backwash Pumps
2 40
40 ft
2,700 gpm
Surface Wash Pumps
2 10
198 ft
- 120 gpm
Wash Water Pumps
2 5
150 ft
75 gpm -
Sludge Lagoon Pumps
2 5.4
25 ft
200 gpm
*For each pump
61

The following is a schematic representation of the Benson wastewater plant:
— ----Filter Backwash' — ----- Dechlorination _
Chlorine System -ost Aeration
Contact Basing I / Tank
WClar.
I
Effluent
Sludge Pump
Waste —Filter Backwash
ge Pump
rculation
Aeration
Tank #3
�--
Mechanical
Bar Screen
Mrs.
CIar, ular. _ ■ —r ■ —Tank #1
#1
Splitte �_
Comminutor By -Pass Box
Screen
Screw Pumps
rit hamber Parshall _ ume
Equalization Aerated
Basins Sludge
Holding
1.4 Project Phase
The requested flow limit increase is for the existing plant and is not part of any phased
project_ The Benson plant discharge is within the nutrient sensitive Neuse River Basin. The plant is
already equipped for phosphorus removal, and it appears likely that some form of nitrogen removal
will be required as well. Depending on the final form that the nitrogen removal requirements take
(plant specific limitations or limitations applied to aggregate discharge of voluntary associations),
some upgrading of the plant to achieve nitrogen removal may also be required. Detailed plans for
this upgrading will be developed once specific nitrogen removal requirements are known. The
existing plant configuration, with its use of multiple long, shallow, oxidation ditches, is readily
amendable to modification for use of a number of different biological nitrogen removal processes.
M

2.0 EVALUATION OF DISPOSAL ALTERNATIVES
2.1 Connection to a Sewer Collection System
The Town of Benson operates its own wastewater collection and treatment system. There is
no other existing sewer system within a five (5) mile radius of the existing Town system. There is
no planned area wide sewerage system expected within the next five (5) years that would be within
a five (5) mile radius of the existing Benson system. Therefore, connection to another sewer
system is not regarded as being a viable alternative.
2.2 Land Based Disposal
Land application is an effective wastewater treatment method that takes advantage of the
physical, chemical, and biological processes that occur when water, -soil, plants, microorganisms,
and the atmosphere interact. Use of a land treatment system eliminates point source discharges
while providing a high degree of treatment and nutrient removal. Land treatment systems are
sometimes found to be the most cost-effective solution to treatment problems. However, land
treatment systems are normally only cost effective when the systems are used as the tertiary
treatment system and when reasonably suitable land area is available: The Town of Benson has
already constructed tertiary treatment facilities capable of treating the design flow of 1.732 MGD.
Therefore, in its case, land application costs would be additive to conventional tertiary system
costs, rather than a true alternative to those costs. Site selection criteria remain unchanged even if
tertiary. treatment is provided as the preliminary treatment system. When selecting potential land
application sites, many factor's must be taken into account, including:
• Site should be selected that has soil groups most suited for the land application
processes under consideration.
• Site should not conflict with the present and anticipated land use and should
reinforce the adopted land use plans.
• Site should be within a reasonable transport distance from the source of
wastewater.
• Site should not endanger sensitive environmental areas such as historic sites or
rare or endangered plants or animal species.
• Site should minimize adverse socio-economic impacts.
• Site should not have geological or groundwater conditions that would adversely
effect the land application treatment process being considered.
• Elevation difference between the site and the source of wastewater should be
minimum to reduce pumping costs.
• The number and size of the available land parcels should also be considered.
7

In order to make a rough approximation of the costs of installing a 1.732 MGD spray
irrigation -system -to -serve --the -T-own-of Benson, -Soil Survey- Maps - of -Johnston -County--were-
reviewed. The soil surveys showed that large acreages of Wagram and Norfolk soils, usually
intermixed with lessor quality soils such as Goldsboro and Bibb soils, are available at a number of
areas within the general vicinity of Benson. Considering these soil types, it was assumed that a site
could be located that could sustain an annual average loading of 1.2 inches per week and that
would require a wastewater storage lagoon (for holding treated wastewater during inclimate
weather) of only 60 days storage size. Based on these assumptions, a 373 acre sprayfield and a
104 MG storage lagoon would be required for land application of the Benson wastewater. The cost
of such a system is approximated as follows:
Item
Quantity
Unit Price-
Extended Total
Transfer Pump Station (from
WWTP to Storage Lagoon)
1
LS
$200,000
Effluent Storage Facility:
Excavation & Fill
$3,400,000
Slope Protection
$2,400,000
Spray Irrigation Pump Station
1
LS
$350,000
Sprayfield Piping
373 acres
$5,500/acre
$2,052,000
Fencing
22,000 LF
$2.10/LF
$46,000
Sitework & Piping
$1,143,000
Access Roads
5 miles
$16/LF
$422,000
Electrical
$55,000
Administrative Bldg. & Equipment Sheds
$120,000
Sub -Total
$10,188,000
Land: Sprayfield '�
373 acres
$5,000/acre
$1,865,000
Land: Buffers & Uneconomic Remnants
250 acres
$5,000/acre
$1,250,000
Land: Storage Lagoon
55 acres
$5,000/acre
$275,000
Equipment
$80,000
Contingencies
$1,019,000
Engineering
$1,019,000
Total Project Cost $15,696,000
These approximate costs are for comparison purposes only. Other costs, such as those for
the conveyance force main, have not been included since it is not known exactly where such a
facility would be located. The cost projection above is therefore something less than the actual
minimum cost of a land application system.
2.3 Wastewater Reuse
There are no golf courses or similar facilities near the Benson wastewater treatment plant
that would have irrigation needs that would justify a water reuse system. There is one large water
using industry within the Benson system, but the products it makes included pharmaceutical grade

materials, and any process water of lesser quality than potable water is likely to prove
--- ---objectionable. Therefore, reuse is- not regarded as a viable alternative -to an --increase in the permitted--- - --
discharge flow.
2.4 Surface Water Discharge
As shown in the December 1996 report, a surface water discharge of 1.732 MGD meeting
tertiary treatment standards can be achieved with the existing wastewater treatment system, at no
additional capital cost. The imposition of nutrient removal requirements may require some capital
expenditures with or without a plant expansion. Should the nutrient removal requirements imposed
be greater than that which could be achieved with only moderate capital expenditures, then
pumping treated effluent to a discharge point in Mingo Swamp, within the Cape Fear River Basin,
would be a viable alternative.
2.5 Conclusions
The wastewater disposal analysis shows that discharge to another sewage treatment system
is not practical. Elimination of the discharge by construction of a land application system would
cost in excess of $15,696,000 and would bring the Town, in effect, only 0.232 MGD of additional
capacity. This is obviously not a viable solution. Wastewater reuse could in theory allow the Town
to treat up to 1.732 MGD but to keep its discharge at or under 1.500 MGD. However, for this
theory to be a reality, there must be a reuse market, which at present does not exist. Increasing the
discharge permit capacity from 1.500 MGD to 1.732 MGD would allow the Town to maximize the
investment it has already made in wastewater treatment capacity. The discharge can be increased to
1.732 MGD without any capital improvements if the present effluent limits remain unchanged.
Some requirements for nitrogen removal appears likely with or without the plant expansion. Under
these circumstances, some capital outlay may be required to add nitrogen removal capability. The
present treatment system is readily adaptable to biological nutrient removal, and assuming any
nutrient removal requirements that might be imposed are reasonable, this should be achievable at a
cost of only a small fraction of that of land application. In the event that nutrient removal
requirements are unreasonable, consideration would have to be given to pumping treated effluent to
Mingo Swamp in the Cape Fear River Basin, where no nutrient removal requirements are
expected.
9

3.0 SUMMARY
The Town of Benson's wastewater treatment plant, due in large part to the presence of
infiltration and inflow, has flows that at times reach, and even exceed, 80% of its design flow. A
two prong approach has been developed for the Town to assure that its wastewater flows do not
exceed its actual treatment capacity. One prong of this approach is an on -going program for
locating and eliminating infiltration and inflow problems. The Town's goal for this program is to
eliminate extraneous flows from its system at least as fast as normal growth adds flows to its
system. It is expected that this program will allow the Town to hold the average daily flows over
the next 5 to 10 years at or near their present levels, if not to actually reduce its flows. The second
prong of the Town's strategy is to provide an additional 232,000 gallons per day of permitted
reserve wastewater treatment capacity while the Town gets its sewer collection system
rehabilitation program underway. This is to be done by re -rating its plant for a higher discharge
capacity. An engineering analysis completed in December of 1996 concluded that the existing plant
can operate as a 1.732 tertiary treatment facility. Accordingly, the Town of Benson has requested
that its NPDES discharge permit be increased from 1.500 MGD to 1.732 MGD.
The North Carolina Division of Water Quality required the Town to evaluate alternatives to
an increase in permitted surface discharge capacity. That evaluation is contained in this, report.
Alternatives considered were discharge to another system, land treatment by spray irrigation, and
water reuse. Discharge to another system was found to be impractical because there is no other -
system within a reasonable distance. Spray irrigation was found .to be too costly (at a cost of at
least $15,696,000 for what would amount to only a 232,000 gallon per day increase in capacity).
Conditions around Benson are such that reuse is also not a practical alternative.
Continuing with the point source discharge, and expanding the permitted capacity by even
the modest amount proposed, could result in the imposition of future total nitrogen limits. If and
when such limits are imposed, the plant may need to be upgraded. The treatment plant utilizes three
long, shallow oxidation ditches, a configuration amenable to modification for biological nitrogen
removal by a number of different processes. Should a degree of nitrogen removal be imposed that
can not be achieved using relatively modest modifications to the existing treatment system, then
pumping of the treated effluent to Mingo Swamp, a tributary of the Cape Fear River, can be
considered.
10

. , • State of North Carolina
Department of Environment,
Health and Natural Resources
Division of Water Quality
James B. Hunt, Jr., Governor
Jonathan B. Howes, Secretary
A. Preston Howard, Jr., P.E., Director
April 25, 1997
Mayor Don H. Johnson
Town of Benson
P.O. Box 69
Benson, North Carolina 27504
Subject: Permit Application Return
NPDES No. NCO020389
Town of Benson WWTP
Vmr,Eounty
Dear Mayor Johnson:
I received your request for modification of your NPDES permit to discharge. Specifically, you requested
that consideration be given to allow this discharge to be increased from 1.5 million gallons per day (MGD)
to 1.732 MGD. After discussions with Mr. Keith Langdon (Town Administrator) and Eric Mills (The Wooten
Company), the Division is hereby returning this request with the following comments.
First, as you may know, the water quality in the Neuse River basin has prompted the Division to
reevaluate the existing Nutrient Sensitive Waters Management Strategy. The modified strategy has not
been finalized, but will likely include limits for total nitrogen for any expanding discharge. The town
should consider this when making future plans to expand above 1.5 MGD.
Furthermore, the town should perform an alternatives analysis as described in the attached document
for any expansion. Please note that there is a provision for the requirements regarding soils analyses for
expanding discharges greater than 1.0 MGD.
Finally, the Town of Benson will need to submit a completed NPDES application form (Standard Form
A) with any resubmittal. If you have any questions or comments, please do not hesitate to contact me at
(919)-733-5083, extension 517.
Sincerely,
T'
David A. Goodrich
NPDES Group Supervisor
cc: Central Files
Raleigh Regional Office/Water Quality Section
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

` MAYOR
DON H. JOHNSON
COMd5510hERS
NATHAN B. BLACKMON
RAY G. SMITH
JACK R. LITTLETON
KENNITH M. DUPREE
LINDELL NORDAN
J.W. PARRISH, JR.
January 13. 1997
Mr. Dave Goodrich, Supervisor
NPDES Group
Oda OF BE��
O
Cy,
OATH CARO��
TOWN OF EENSON
P.O. BOX 69
303 EAST CHURCH STREET
NORTH MOLINA
27504
[phone]
FAX [phone]
North Carolina Department of Environment
Health and Natural Resources
Post Office Box 29535
Raleigh, North Carolina 27626-0535
Re. NPDES Permit NC 0020389
Benson, North Carolina
Dear Mr. Goodrich:
TOWN ADM ASTRATOR
KEITH R. LANGDON
TowN CLERK
CAROLYN A. NORDAN, CIVIC
TAx COLLECTOR
ROSALIE G. WEST
TOWN ATTORNEY
DONALD A. PARKER
The Town of Benson hereby requests that the above referenced permit, issued to the Town, be modified
to allow an average monthly discharge of 1.732 million gallons per day. This is the maximum monthly average
discharge rate that an engineering study shows our treatment plant can handle without any physical
modifications. Infiltration and inflow have caused plant flows to reach, and, at times, exceed our currently
permitted capacity of 1.500 million gallons per day. Increasing the permitted capacity of the plant will allow the
Town to continue to grow and to operate its treatment plant without permit violations while it continues to work
to eliminate infiltration and inflow sources. A $400.00 check for the permit modification fee, and three (3)
copies of the aforementioned engineering study, are enclosed in support of this request.
If any additional information is required, please let us know.
Sincerely
Cam'Nat�-��
Don H. Johnson
Mayor
DHJ/cros
attachments
C:\MAY0R\G00DR1CH.DHJ

TOWN OF BENSON
WASTEWATER TREATMENT
PLANT CAPACITY EVALUATION
DECEMBER 1996
r SEAL
9792
w • �
EVERET"I'E L. CHAALISS, JR., P.E.
THE WOOTEN COMPANY
Engineering • Architecture • Plzuj! ng t-;
120 North Boylan Avenue "
Raleigh, North Carolina 27603 U

TOWN OF BENSON
WASTEWATER TREATMENT
PLANT CAPACITY EVALUATION
DECEMBER 1996
• SEAL
9792
oE
eaaaaas a 1,1.,,E
EVERETTE L. CHkM LISS, JR., P.E.
THE WOOTEN COMPANY
Engineering • Architecture • Planning
120 North Boylan Avenue
Raleigh, North Carolina 27603

Table of Contents
Page
1.0 Purpose and Methodology ........................................ 1
2.0 Description of Existing Units and Limiting Parameter for Each Unit ............. 1
3.0 Analysis of Limiting Factors - Flow Related Units ........................ 7
4.0 Evaluation of Non -Flow Limited Units ................................ 9
5.0 Conclusions ................................................. 13
Tablel.......................................................... 2
Table2......................................................... 10
Figure.......................................................... 6

1.0 PURPOSE AND METHODOLOGY
This study has been undertaken to determine the actual safe wastewater treatment plant capacity
available to the Town of Benson. The Town is currently permitted to discharge 1.5 mil gals per
day of wastewater. During a recent thirteen month period (September 1995 through September
1996) flows averaged 1.312 mil gals per day, which is 87.8% of the permitted capacity. Although
the flow average is somewhat distorted by the effects of two hurricanes and a tropical storm, even
under more ordinary flow conditions average flows approach and often exceed 80% of the design
capacity. The Town of Benson has developed a two prong approach to assuring that its wastewater
flows do not exceed its permitted capacity. One prong involves an ongoing sewer rehabilitation
effort aimed at reducing extraneous infiltration and inflow. The second prong of the Town
approach is the subject of this study, and involves rerating the capacity of the existing treatment
plant. Rerating of the treatment plant to a higher capacity should be possible at Benson due to
several factors, the most important of which are:
- A substantial portion of the current flows consist of process wastewater from an
industry which is substantially lower in pollutant concentrations (BOD5, TSS,
and ammonia) than the design concentrations for the plant.
- The plant has extra -ordinarily large flow equalization capabilities which can be
used to minimize peak loading on hydraulically limited treatment plant
components.
- The conservatism inherent in the original plant design.
The above three factors combine to allow the plant to successfully treat more than its 1.5 mil gal
per day rated capacity. The purpose of this study is to quantify just how much more than the
permitted capacity the Town can reasonably expect its facility to be able to treat. The methodology
used in making this quantification consists of reviewing all major treatment plant processes to
determine which wastewater characteristic most limits its performance, determining the maximum
wastewater flow that each component can handle, and finally comparing limiting components to
determine which component will govern overall plant performance.
2.0 DESCRIPTION OF EXISTING UNITS AND LIMITING PARAMETER FOR EACH UNIT
Table 1 contains a detailed description of the existing wastewater treatment plant. Figure 1 is a
schematic flow diagram of the treatment plant. Reviewing those components it can be sent that the
following principal components are flow limited.
Mechanical & Manual Screens & Comminutor
Grit Chamber
Parshall Flume
Influent Screw Pumps
-1-

TABLE I
DESIGN DATA OF BENSON WASTE TREATMENT PLANT
Design Population
3,924
Design Flows, mgd
Average daily flow
1.5
Peak hydraulic flow
3.75
Design Waste Loadings, lb/day
BOD5 (Bio-Chemical Oxygen Demand, 5 day 20° C)
2,500 (200 mg/L)
TSS (Total Suspended Solids)
2,500 (200 mg/L)
NH3-N (Ammonia Nitrogen)
250 (20 mg/L)
Phosphorous
100 (8 mg/L)
Bar Screens
Mechanical
Number of units
1
Design flows, ADF, mgd
1.50
PDF, mgd
3.75
Channel width, ft
2
Channel depth, ft
5
Motor horsepower, hp
0.5
Unit power control
Time Clock
Maximum rake lift capacity, lb
462.0
Manual
Number of units
1
Channel width, ft
1.5
Channel depth, ft
2
Unit capacity, mgd
1.65
Grit Chamber
Number of units 1
Length, ft 17
Width, ft 1.25
Average water depth, ft 1.50
Detention time at peak flow, min 0.30
Velocity at peak flow, ft/sec 1.36
Surface overflow rate at peak flow, mgd/sq ft 0.077
Method of grit removal Mechanical
Comminutor
Number of units 1
Unit size, in 15
Unit capacity, mgd 2.4
Size of drive unit, hp 0.75
-2-

Table 1 cont'd.
Parshall Flume (or flow measuring)
Number of units, 9-inch size
Aeration Tanks (Oxidation Ditches)
Number of units 3
Liquid depth, ft 5
Unit Volume, mil gal 0.618
Total Volume, mil gal 1.854
Detention time, average hr 30
BOD5 to aeration tanks, lb/day, average 2,500
Organic loadings to tanks, lb BOD5/1000 ft3, average 10
MLVSS concentration, mg/L 2,200
F/M ratio, lb BOD5/lb MLVSS 0.09
MCRT or SRT, days (@ 10° C, Yn=0.65, BODR=98%) 27
Sludge recycle ratio 1:1
Aeration Facilities for Aeration Tanks
Type of aeration Mechanical, brush type
Number of aerators, 27 z — in x 10 ft long brush
rotor with 7.5 hp drive unit, each/tank 4
Total number of brush aerators 12
Total horsepower provided, hp 90
Aerator capacity at 6-in immersion, lb 02/hr/ft of rotor 1.74
Total aeration capacity, lb 02/hr 208.80
Total oxygenation capacity, lb O2/lb BODr, average 2.00
Secondary Clarifiers
Number of units, 35 ft diam x 12 ft SWD
2
Unit Volume, gal
86,359
Number of units, 35 ft diam x 10 ft SWD
2
Unit Volume, gal
71,966
Total Volume, gal
316,650
Detention time at average flow, hrs
5.07
Unit surface area, sq ft
962
Total surface area, sq ft
3,848
Surface overflow rate, gpd/sq ft
390
Unit weir length, ft
110
Total weir length, ft
440
Weir overflow rate, gpd/lf
3,410
Type of sludge removal
Pump
Filters
Number of filters, 10 ft x 12 ft
5
Total surface area, sq ft
600
Filtration rate at average daily flow, gpm/sq ft
1.74
Filtration rate at peak daily flow, gpm/sq ft
4.34
Maximum wash rate at 20° C, gpm/sq ft
15.0
-3-

Table 1 cont'd.
Filter Media
Anthracite Medium - 2 ft 3 inch depth of the media. Particle sizes ranging from 1.2 mm to 1.6
mm, with a maximum uniformity coefficient of 1.4 and not more than
10% by weight being no more than 1.2 mm.
Anthracite has a specific
gravity of 1.57.
Silica Medium - 12-inch depth of the media. Particle sizes ranging from 0.50 mm, with a
maximum uniformity coefficient of 1.6 and not more than 10% by
weight being smaller than 0.50 mm. the specific gravity of sand is 2.50.
Gravel - 13-inch depth of the media consisting of-
4-inch 1 /8" x No. 16 mesh
3-inch 1/8" x 3/8"
3-inch 3/8" x 1"
3-inch 5/8" x 1"
Underdrain system
Wheeler bottom type
Caustic Feed System (for alkalinity and pH Control)
Total lime storage capacity, cu. ft
1,800
Number of feed pumps
2
Feed rate, gal/hr
0 - 0.5
Alum Feed System (for phosphorus removal)
Number of storage tanks, 12'-0" ID x 18'-6"
2
Unit capacity, gal
15,000
Total capacity, gal
30,000
Number of feed pumps
2
Feed rate, gal/hr at 150 psig back pressure
50
Motor horsepower, hp
1
Chlorination System
Chlorine Contact Tanks
Number of tanks 23'-6" x 8' - 8" x 6' - 6" SWD
2
Unit volume, gal
8,593.5
Total volume, gal
17,187
Detention time at average daily flow, min.
16.5
Chlorine Feed System
Number of chlorinators
2
Chlorine feed rate, lb/day
20 - 200
Number of one ton cylinders
4
Filter Backwash Clear Water Storage
Number of tanks - 18'-8" x 18'-0" x 6'-6' /11'-3" x 9'-10" x 5'-0"
1
Total volume, gal
20,475
Post Aeration
Number of units 18'-6" x 18'-0" x 6'-6"
1
Total volume, gal
16,190
Detention time at average daily flow, min.
15.5
-4-

Table 1 cont'd
Type of aeration Submerged self -aspirating type
Number of aerators, 7.5 hp 1
Aerator capacity, CWTR at 41 cfm air flow and STP in lb 02/hr 26
Dechlorination System
Solution type
Number of metering pumps
Capacity, gph
Solution tank size, gal
Aerated Sludge Holding Lagoon (for sludge stabilization, disposal)
Number of lagoons
Size of lagoon
Area at water surface, sq ft
Area at bottom surface, sq ft
Side slopes
Liquid depth, ft
Total volume, gal
Sodium sulfite
2
0 to 1.5
250
1
191 ft x 299 ft = 57,110
166 ft x 274 ft = 45,310
1.5:1
8.5
3,080,220
Stabilization Lagoons (for equalization of influent flow & filter backwash waste)
Number of lagoons
Size of lagoon
Area at water surface
Area at bottom
Slide Slopes
Liquid depth
Volume of each lagoon, gal
Total volume, gal
Pumps
Lar eg_r Lagoon Smaller lagoon
315' x 575' = 181,125 sq ft. 1/2 (385+265)x795=258,375 sq ft
300' x 560' = 168,000 sq ft 1/2 (370+250)x780=241,800 sq ft
2.5:1
3.0 ft
Screw Pumps
Screw Pumps
Filter Lift Pumps
Sludge Recirculation Pumps
Sludge Waste Pumps
Scum Pumps
Filter Backwash Pumps
Surface Wash Pumps
Wash Water Pumps
Sludge Lagoon Pumps
5,611,960
9,456,760
2
No.
hp/each unit
TDH
Design Capacity*
1
5
7 ft
1,750 gpm
2
3
7 ft
1,370 gpm
3
15
34 ft
1,300 gpm
2
10
17 ft
1,050 gpm
1
1.5
loft
100 gpm
2
1.5
10 ft
100 gpm
2
40
40 ft
2,700 gpm
2
10
198 ft
120 gpm
2
5
150 ft
75 gpm
2
5.4
25 ft
200 gpm
* For Each Pump
-5-

Waste
Bar Screen
Filter Backwash
Filters
Clar. uHandlin
#4 Unit
Lime _®
Claz. Claz.
# #1
Comminutor By -Pass
Screen _
Equalization
Basins
Dechlormation
Chlorine System —post Aeration
Contact Basin I / Tank
I
Effluent
Filter Backwash
Sludge Pump
Recirculation
Screw Pumps
Aerated
Sludge
Holding
Aeration
Tank #3
—Aeration
Tank #2
Aeration
Tank #1
Figure 1
Schematic of Benson Wastewater Treatment
Facility
Final Clarifier*
Filter Lift Pump Station
Tertiary Filters
Chlorination System
Dechlorination System
Sludge Recirculation Pumps
Sludge Wasting Pumps
*Solids loading & phosphorus loading could also potentially limit capacity
The following components are expected to be limited by BOD5 loading:
Aeration Basins (Oxidation Ditches)*
Aerated Sludge Holding Lagoon **
* Hydraulic loading and ammonia loading could also potentially impact minimum allowable loading
** Influent TSS and phosphorus could also impact potential maximum allowable loading
The following components are expected to be limited by influent phosphorus loading:
Alum Feed System
Caustic Feed System
* Ammonia loading could also potentially impact minimum allowable loading
'lds

Certain components are clearly going to be impacted only by one wastewater characteristic, (i.e.
pumps will be effected by flow only) while others could be limited by more than one parameter,
depending on loading. In cases where more than one waste characteristic could potentially be the
governing factor in determining a unit process's overall perfonnance, the unit has been listed under
the waste characteristics most likely to be the limiting factor with domestic wastewater. As an
example, clarifiers are listed as being flow limited. However, solids loading can also limit clarifier
performance. Solids loading in turn could be determined by BOD5 loading (which will govern the
mixed liquor of suspended solids concentration maintained in the aeration basins which feed the
clarifiers) or by phosphorus loading (which determines the alum feed rate to the clarifiers which in
turn determines the mass of chemical precipitate which the clarifiers must handle).
3.0 ANALYSIS OF LIMITING FACTORS - F+LOw RELATED UNITS
Perhaps the simplest units to evaluate are the flow related units. The simplest of these units to
evaluate are the pumps. The last part of Table 1 contains a sumimary listing of the major pumping
systems employed at the plant. Three (3) influent screw pumps are used at the plant, one with a
capacity of 1,750 gpm, and two with capacities of 1,370 gpm each. Therefore, with the largest
pump out of service, the influent pumps can still handle a flow of 3.946 mil gals per day (2 pumps
x 1,370 gpm x 1,440 rains./day = 3,946 mil gals per day). Ordinarily, a lessor average daily flow
than the pump capacity would have to be considered to account for peak flows. However, since
the Benson plant has 9.457 mil gals of equalization capacity, it would, at least in theory, be
possible to equalize all peak flows and operate the plant at only one flow rate, the average daily
flow. Therefore, the limiting plant capacity of the influent pumps will be considered 3.946 mil gals
per day. Three (3) filter lift pumps, each having a capacity of 1,300 gpm are provided. Assuming
one pump is out of service, these pumps would have a capacity of 3.74 mil gals per day (2 pumps
x 1,300 gpm x 1,440 mins/day = 3.74 mil gals per day). The filter backwash and surface wash
pumps are matched to the needs of the filters, and therefore will not directly effect plant capacity.
The wash water pumps are sized based on projected incidental plant needs for clean-up, and
therefore will have no impact on plant capacity. The sludge lagoon pumps, scum pumps and
sludge waste pumps are sized based on the need to maintain minimum velocities through
established minimum size sludge wasting and scum piping lines. Each of these pumps is needed to
run only a tiny fraction of the day, and therefore these pumps will have no impact on plant
capacity. Sludge recirculation pumps do, however, have some potential impact on overall plant
capacity. There are two (2) such pumps, each rated at 1,050 gpm. Sludge recirculation rates
employed vary with a number of factors, but assuming a recirculation rate of 80% of the average
-7-

daily flow is not unreasonable (some plants have been successfully operated with recirculation
rates as low as 50% of average daily flow, but it would be imprudent to assume that such a low
recirculation rate could be reliably used). Therefore, the limiting capacity due to the recirculation
pumps is estimated as being 1.890 mil gals per day, assuming one of the two pumps is out of
service (1,050 gprn x 1/80% x 1,440 rains/day = 1.890 roil gals per day). This limiting capacity
could be increased by some relatively minor structural changes. Additional piping and valves could
be added, allowing the sludge wasting pumps to also be used for sludge recirculation. This would
add an additional 0.288 mil gal per day of capacity, assuming the sludge wasting pumps were
available for recirculation 80% of the time, with the remaining 20% used for actual sludge wasting.
(2 pumps x 100 gpm/pump x 80% available x 1,440 min.x 1/80% = 0.288 mil gal per day).
Alternatively, an entirely new sludge recirculation pump and motor could be purchased and made
available for service. This would add an additional 1.890 mil gals per day of reliable capacity to the
system. Of all the pumps, sludge recirculation capacity is the limiting factor, limiting flows to
1.890 mil gals per day. However, with relatively minor changes to piping and valves, this figure
could be increased to 2.178 mil gals per day. The purchase of a standby sludge recirculation pump
and motor could result in a capacity of 3.78 mil gals per day, essentially matching the 3.74 mil gals
per day capacity of the filter lift pumps.
Other unit processes besides pumps are hydraulically limited. These other processes include the
screens and comminutor, flow metering, clarifiers, tertiary filters, and chlorination and
dechlorination systems. Because of the enormous equalization capacity at the plant, peak flows can
be considered tantamount to average daily flows when evaluating the capacity of these units. The
mechanical screen has a capacity of 3.75 mil gals per day. When it is out of service, screening can
be accomplished with a manual screen and a comminutor having a combined capacity of 3.9 mil
gals per day. Therefore, the limiting capacity of the plant screening is 3.75 mil gals per day. The
grit chamber is designed for that same 3.75 mil gals per day flow rate. Benson uses a 9-inch
Parshall Flume. Such a flume can accurately measure flows up to 5.73 mil gals per day.
Therefore, none of the headworks will limit plant capacity to a greater extent than the limitations
imposed by the plant pumping systems.
Clarifiers and tertiary filters are unit processes whose performance is greatly impacted by flow
rates, and for which no simple, relatively inexpensive means exists to increase capacities. There
are four clarifiers having a total combined surface area of 3,848 square feet. A 450 gpd per square
foot loading rate is generally considered to be a reasonably conservative clarifier loading. Based on
that loading rate, the Town of Benson should be able to treat 1.732 mil gals per day of wastewater
(3,848 sq ft x 450 gpd/sq ft = 1.732 mil gals per day). Even should one clarifier be out of service,
-8-

with a flow of 1.732 mil gals per day an overflow rate of 600 gpd/sq ft could still be achieved. 600
gpd/sq ft is considered to be a reasonable design overflow rate for activated sludge system
secondary clarifiers by many authorities. Typical design wastewater filtration rates range from 2 to
as high as 10 gpm per square foot. Using a conservative design value of 3 gpm per square foot,
and considering that one 120 square feet filter is being backwashed, the Benson plant would still
have 480 square feet of filter area which could accommodate an average daily flow of 2.074 mil
gals per day. The most limiting flow factor of all major units is therefore that of the clarifiers, with
a safe capacity of 1.732 mil gals per day. At this rate, the chlorination/ dechlorination system still
needs to be checked for adequacy.
The existing chlorine contact chambers have a volume of 17,187 gallons. The adjoining filter
backwash clearwell storage provides an additional 20,475 gallons of tank volume for chlorine
contact. Therefore, the total effective chlorine contact volume is 37,662 gallons. At an average
daily flow of 1.732 million gallons, this volume will provide a detention time of 31 minutes.
Assuming a chlorine dose of 7 mg/L is required for effective disinfection, 101 pounds per day of
chlorine will be needed (1.732 mil gals per day x 8.34 x 7 mg/L = 101 lbs/day). Referring to Table
1, the existing chlorine feed system can deliver up to 2001bs. per day. The dechlorination system
is matched in capacity to the chlorination system, and therefore will also be able to accommodate a
1.732 million gallon per day flow.
4.0 EVALUATION OF NON -FLOW LIMITED UNITS
While the preceding analysis has shown that the treatment plant can accept an average daily flow of
up to 1.732 mgd, before the Town accepts the flow, or the State agrees to permit the flow, there
needs to be some reasonable level of assurance that BOD, TSS, ammonia, and phosphorus loads
associated with this flow will not overload those plant components whose performance is related to
loading of these pollutants. In order to make this determination, some projections regarding future
wastewater characteristics must be made. During the 13 month period from September 1995 to
September 1996, influent BOD5 concentrations averaged 77 mg/L, influent TSS concentrations
averaged 76 mg/L, and influent ammonia concentrations averaged 10 mg/L (see Table 2). Influent
phosphorus is not measured, but since effluent phosphorus averaged 1.5 mg/L, without the Town
using the phosphorus removal treatment processes at the plant, it is conservatively assumed that
influent phosphorus levels were not more than 4 mg/L. The low concentrations for all pollutant
parameters are due largely to the presence of a high volume, low strength industrial waste,
although infiltration and inflow also contribute to the low influent pollutant concentrations. Influent
concentrations of all pollutants are expected to increase in the future. Two factors will contribute to
the increase in treatment plant influent pollutant concentrations. The first of these is the ongoing
-9-

sewer rehabilitation program the Town is undertaking. This program will eliminate flows which
essentially have no pollutant load so that each gallon eliminated will result in the remaining flow
into the treatment plant having higher pollutant concentrations. The second factor is that growth in
the Town service area is expected to bring additional flows with greater pollutant concentrations
than the existing wastewater. In order to project the future plant pollutant influent concentrations at
an average daily flow of 1.732 mil gal per day, the following assumptions have been made:
(1) The Town will eliminate approximately 10% of its existing average daily
wastewater flow through its ongoing sewer rehabilitation program, (i.e., will
eliminate 131,000 gallons per day of infiltration/inflow on a full year, average
daily flow basis)
(2) The 131,000 gallons per day of flow eliminated from 19 reduction will not
eliminate any BOD5, ammonia, TSS, or phosphorous loading on the plant.
(3) The 131,000 gallons per day of eliminated infiltration and inflow will be
replaced, through growth, with municipal type wastewater, and an additional
415,000 gallons per day of municipal type wastewater will be added to the
system, so that the treatment plant will eventually run at an average daily flow of
1.732 mil gal per day, (i.e. the plant will eventually receive 546,000 more
gallons per day of wastewater and 131,000 less gallons per day of rain water
and groundwater).
(4) All future wastewater flows will have a BOD5 concentration of 350 mg/L, a TSS
concentration of 300 mg/L, an ammonia concentration of 30 mg/L and a
phosphorous concentration of 6 mg/L.
Table 2
Benson Wastewater Treatment Flow Monitoring Data
Influent
Effluent
Date
Flow
BOD5
NH3-N
TSS
BOD5
NH3-N
TSS
TN
TP
(mgd)
Sep-95
0.996
74
12.35
93.7
2.6
0.17
6.62
16.03
2.05
Oct-95
1.747
71
9.39
80
2
0.23
10.03
11.47
1.55
Nov-95
1.447
59
9.9
69
2.9
0.47
7.74
10.44
1.17
Dec-95
1.113
93
12.57
81.2
3.5
1
11.62
10.61
1.51
Jan-96
1.186
77
8.93
81.8
5.5
1
14.24
8.01
1.83
Feb-96
1.318
68
7.92
56
4.8
1.14
8.97
12.08
1.05
Mar-96
1.193
65
9.95
72
2.37
0.34
7.61
10.76
1.52
Apr-96
1.208
67
10.54
89
2
0.3
6.82
10.29
1.49
May-96
1.310
91
10.81
93
2.8
0.31
7.66
11.01
1.73
Jun-96
1.311
69
10.2
80
1.3
0.31
7.68
11.06
1.61
Jul-96
1.186
69
10.23
77
1.9
0.33
10.18
10.5
1.53
Aug-96
1.380
113
10.05
58
1.4
0.4
2.69
7.85
1.32
-10-

Influent
Effluent
Date
Flow
BOD5
NH3-N
TSS
BOD5
NH3-N
TSS
TN
TP
(ingd)
Jul-96
1.186
69
10.23
77
1.9
0.33
10.18
10.5
1.53
Aug-96
1.380
113
10.05
58
1.4
0.4
2.69
7.85
1.32
Sep-96
1.721
89
7.06
59
1.5
0.2
4.25
8.65
1.54
Ave.
1.317
77
10
76
2.6
0.5
8
11
1.5
Using the previously listed assumptions, it is possible to calculate the plant pollutant loadings
at a flow of 1.732 mil gal per day. This is done as follows:
Existing Baseline Loads (average loads from 9/95 through 9/96):
BOD5: 1.371 mgd x 8.34 x 77 rng/l = 846 lbs/day
TSS: 1.371 mgd x 8.34 x 76 mg/l = 835 lbs/day
NH3-N: 1.371 mgd x 8.34 x 10 mg/1 = 110 lbs/day
P: 1.371 mgd x 8.34 x 3.8 mg/l = 44 lbs/day
Projected Future Load Increases:
BOD5: 0.546 mgd x 8.34 x 350 ing/1=
1594 lbs/day
TSS: 0.546 mgd x 8.34 x 300 mg/l=
1366 lbs/day
NH3-N: 0.546 mgd x 8.34 x 30 mg/1 =
137 lbs/day
P: 0.546 mgd x 8.34 x 6 mg/1 =
27 lbs/day
Total Projected Future Pollutant Loads
BOD5: 846 lbs/day+15941bs/day'"- 72440 lbs/day
TSS: 8351bs/day+1366lbs/day = 2201 lbs/day
NH3-N: 1101bs/day+1371bs/day = 247 lbs/day
P: 44lbs/day+271bs/day = 71 lbs/day
Comparing the projected loads to the design loads for the treatment system given in Table 1
shows that in all cases the actual future plant loadings will be less than the loadings for which the
plant is designed. This means that all aeration, chemical feed, and sludge handling facilities are
adequately sized. However, the detention tune within the aeration basins will be shortened, and the
mass loading on the final clarifiers potentially increased by the greater design flow. Therefore, the
adequacy of the existing aeration basins and clarifiers at 1.732 mil gal per day flow must be
determined
The aeration basins (oxidation ditches) have a combined volume of 1.854 mil gals At a
design flow of 1.732 mil gals per day, a detention time of approximately 26 hours will be
provided. The system should, therefore, be able to continue to operate as an extended aeration
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sludge system will need an SRT (solids retention time) of 25 days, (Figure 14-11, ASCE MOP
36, 1977). The mixed liquor of suspended solids required to achieve this SRT is calculated as
follows (equation source: page 235, ASCE MOP 36, 1977):
SRT —a(M)—b
where: F = food (BOD5 load in pounds)
M = mass of microorganisms (mixed liquor of volatile suspended solids, in pounds)
a = cell yield coefficient, typically 0.7 for extended aeration systems
b = endogenous decay coefficient, typically 0.04 for extended aeration systems.
Rearranging to solve for M, the equation becomes:
M= aF
1
(SRT
)+ b
Substituting values for variables, M is calculated as:
M= 0.7 (2440 lbs)
(Y+.04
5)
M= 21, 3501bs
The corresponding mass of total mixed liquor, assuming a 70% volatile solids content, is 30,500
lbs (21,350 lbs/70% = 30,500 lbs), and the required mixed liquor of suspended solids (MLSS)
concentration is determined as follows:
MLSS = 30,5001bs
8.34 x 1.854 mil. gal. aeration basins
=1972 mg / L
Maintaining a 1972 mg/1- MLSS is not an unreasonable expectation, and therefore the aeration
basins are adequately sized to allow a 1.732 mil. gal. per day design flow.
The mass loading on the final clarifiers at a 1.732 roil. gal. per day flow is calculated as follows:
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1.732 mgd x 8.34 x 1972 mg / L
Mass Loading = 3848 sq ft of clarifier surface area
= 7.4 lbs per sq ft per day
7.4 lbs per sq ft is substantially below the 30 to 35 lbs per square foot per day loading generally
considered as acceptable maximum solids loadings for clarifiers used within activated sludge
systems. The adequacy of the clarifiers from a hydraulic stand point has been previously
demonstrated. Therefore, the clarifiers can safely be assumed as adequate to accept a 1.732 mil gal
per day design flow.
5.0 CONCLUSIONS
The Town of Benson wastewater treatment plant can accept and successfully treat considerably
more than its currently permitted capacity of 1.5 mil gals per day. This ability can be attributed to a
number of factors, the most significant of which are the relatively low pollutant concentrations
found within the wastewater, the presence of an extraordinarily large equalization facility, and the
conservatism of the original plant design. A unit process by unit process evaluation of the plant has
been conducted and based on that evaluation it has been concluded that the lirniting factor in plant
performance will be the size of the final clarifiers. The final clarifiers could perform adequately at
an average daily flow of 1.732 rnil. gals per day. Accordingly,it is concluded that the plant can
operate as a 1.732 mil. gal per day tertiary treatment facility. The Town of Benson should
therefore submit a request to the North Carolina Division of Water Quality that its plant be rerated
as a 1.732 mil gal per day plant, and that its NPDES Permit be correspondingly modified.
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