Town of Cary: History of FOG Program
Town of Cary: History of FOG Program
Fats Oils and Greases Fats, Oils, and Greases
Control Ordinance: Adopted 12-10-98p
Fats, Oils, and Greases vs.
C ll ti
S t
P f
Collection System Performance
Expectations in 1996
pectat o s
·996
Without a FOG program, sewer main PM costs and #SSOs escalate
With FOG program expect reduced liability and exposure to State fines & 3rd party NGO l it
lawsuits
With FOG program, expect restoration of sewer capacity, in conjunction with PM
sewer capacity, in conjunction with PM
Without a FOG program, expect City to absorb more costs to maintain sewer
i capacity
North Carolina “Clean Water Act of 1999”
z River degradation from point/non-point sources •In ’90s SSOs were identified as “next
frontier” of regulatory oversight in North Carolina and Region IV, EPA
• NC Legislature passed its own Clean Water Act
•Stipulated penalties for SSOs,
•Stipulated a sewer collection system permit (much like NPDES)
•Mandated FOG programs with
Fats, Oils, Greases DO cause
sewer main blockages: proof
Hardened grease
deposits from frying activity
caused blockage and llarge raw sewage
overflow into
homeowner’s yard and homeowner s yard and nearby stream
Example: Accumulated grease
just 3 months after steak house
SSOs: Their Environmental Impact
(no CSOs in NC)
SSOs are a threat to health, safety, welfare of the public SSOs cause d h endangerment to the environment SSO l t th
SSO cleanups cost the Town many thousands of dollars
State mandate: Alleviate SSO’s and restore
se er capacit
Onl highl treated
sewer capacity. Only highly treated
wastewater discharges permitted
1997 Decision: Follow Sound
Engineering Principles or Biased
Engineering Principles or Biased
Market Performance Claims?
Cary Goal: Follow bona fide hydraulic principles
Difficult to achieve desirable goals using unrealistic g g means (re: small traps’ removal efficiency vs larger interceptors)
What are desirable goals? - in 90’s most in US thought 100 mg/L FOG was absolute goal
Not many had heard of 25% “rule”
Small grease traps worked just as well in all g p j applications as larger GIs with more HRT
In 1997, FOG program was target of
major criticism of f t re to be To n
major criticism of future to-be Town
Councilman with political aspirations
Letters to editor in paper criticizing: - rationale used by Town (Leon)y ( )
- objectives
- affected FSEs
Letters also alleged Town conspiracy to hinder small businesses
Letters became personal
Criticizer was a plumber with ties to GT C p G
manufacturing consortium, whose Ex. Director
Turning to Science: 2001
Introduced myself to NC State University
Introduced myself to NC State University Departments of Civil Engineering, Ag
Engineering and Food Science Engineering, and Food Science
Their literature searches, re: academic studies
& i l FOG SSO d i
& articles on FOG, SSOs - unproductive
Basis for research grant proposals: EPA, WEF, WERF
1996 – 1999: SSO’s and other
Non Point Discharges: (ag storm
Non-Point Discharges: (ag, storm
water, atmospheric deposits)
,
p
p
)
result in nutrient load increase to
i
li
S
d
Neuse River to Pamlico Sound:
Increased nutrients stimulate and
accelerate algae growth (bloom)
Political Fallout; PACs and NGOs spar
Political Fallout; PACs and NGOs spar
Algae increase causes fish population
Unpermitted discharges, continued
I i fi h b ( h l )
Increase in fish numbers (schools)
contributes to dynoflagelate Phisteria
tb k t d b i ti t t
outbreaks: asserted by scientists to cause unnatural predation on fish
Death of algae and its decomposition causes oxygen levels to decrease: causes fish kill
SSO’
l d t
SSO’s can cause or lead to:
Fi h kill Public outcry & fear Fish kills Public outcry & fear
And the Waters Turned to Blood
by Rodney Barker, 1997
And the Waters Turned to Blood tells the story of Phisteria, a dinoflagellate that has sprung up in North Carolina’s rivers and
estuaries as a result of pollution. Displaying
h t i ti b f i di
characteristics never before seen in a dino,
Phisteria attacks the nervous system in both fish and humans leading to the death of
fish and humans, leading to the death of
billions of fish and permanent brain damage in people.
SSO impact on streams: Locally
Sanitary sewage is high in organics andSanitary sewage is high in organics and pathogens.
Clean up of a stream/land area after a SSO
Clean up of a stream/land area after a SSO is EXPEN$IVE!Avg. cost, per SSO=$1,500
M $30 000 Mi $200 (C ’
Max = $30,000, Min = $200 (Cary’s experience)
Call for Science to Help Cities with
Ca
o Sc e ce to
e p C t es w t
FOG Program Decisions: 2001 - 2008
Science/Engineering needed to address:
Science/Engineering needed to address: - grease interceptor design
- hydraulic characterization in GI
- effects of solids/FOG cap buildup in GIp p - effects of FOG on sewer pipes: how?
FOG deposit characteristics (40 US cities) - FOG deposit characteristics (40 US cities) - Effect of types of FOG (animal FOG vs
AT LAST! Science to Target FOG Issues!g
2002: Hot Water Only Pre-Rinse
procedure: for bona fide hardship
The use of manual or Automatic grease
recovery systems may be used in certain
circ mstances here circumstances where space is limited.
Specific conditions
Specific conditions
must be met to qualify for this grease removal g configuration
2003: NC State University Civil
E
i
i
D
t
t GI d i
Engineering Department: GI design,
flow characterization – strategies
ow c a acte
at o
st ateg es
6” vented baffle tee
Interior baffle: Located 2/3 distance of tank length
2005: Developing Fast FOG
Screening Procedures: NCSU &
Sc ee
g
ocedu es: NCSU &
Town of Cary
Wilks Infracal Wilks Infracal
Implementing Grease Control: Effects
p e e t g G ease Co t o :
ects
Reduced Number & Frequency of SSOs
12
Reduced Severity of SSOs
Reduced Town costs associated ith SSO l d PM
8 10 12
Jan
with SSO cleanup and PM
Reduced Liability and exposure to Town 6 8 Jan Feb Mar Apr May Jun 1996 – 1997:avg 55 SSOs/yr 1998 – 2007: avg 3 SSOs/yr 2 4 Jun
directly from FOG.
2008: developing training for sewer collections maintenance
0
BEFORE FOG Program
AFTER FOG program
sewer collections maintenance staff to better characterize & ID blockage causes
Original Town Requirements, until
2006 Now have “Action Levels”
2006. Now have Action Levels
for FOG (200 ppm, as HEM), for
Ch
i “H
S
”
Chronic “Hot Spot” users
Grease trap effluent (discharge) cannot
contain more than a certain ppm (parts per million) fats, oils, grease, by certified
laboratory analysis
275 ppm (if freon is used by lab)pp ( y ) z 325 ppm (if hexane is used)
No solids greater than ½ inch in anyNo solids greater than ½ inch in any diameter may be discharged
2000: Original Side by Side FOG
Analysis Comparisons
Method 413 - Freon Extraction
Method 1664 - Hexane ExtractionMethod 1664 Hexane Extraction
FINDINGS:
M h d 413 i ld hi h f
Method 413 yields higher recovery of animal/plant FOG than Method 1664
Town of Cary: Study indicates values are approximately 25% higher by using METHOD 413. Ordinance to be revised.
Grease Trap Size: 24 minutes Hydraulic
R
i
b M
i
F
l f
O
Retention, by Manning Formula for Open
Channel Flow
1999: Original and still in effect
Based on
: drainage fixtures
Based on
: drainage fixtures
Sink bowl size: inches
Type of drain pipe( PVC, iron, copper)
Slope size of drain pipe (1 5” 2 0”)
Slope, size of drain pipe (1.5 - 2.0 )
Dishwasher rating, can wash
2005 – began using electronic field
data capture technology
Special forms intergrate with pens Pens put ink on paper and capture data electronically
lt i d ffi i d #’ f i ti f d result = increased efficiency and #’s of inspections performed per week
New FOG Ordinance: 2006
Major changes to 1998 version
“Program Acknowledgement Certificates, in lieu ofpermits issued to all FSEs
Ubiquitous numeric limits removed; Action Level limits
Ubiquitous numeric limits removed; Action Level limits imposed for chronic bad actors
Annual fee assessed all FSEs ($120/year)
“Community GIs” addressed – ownership/responsibilites addressed
Various variance conditions/situations addressed
FOG program based ERP adopted
Revised sizing spreadsheet; now includes intermittent flow de ices: hoses fa cets tilt kettles etc
On-Site Treatment - Decanting: A Bona
On Site Treatment Decanting: A Bona
Fide GI Maintenance Option
Effective Method of Minimizing Effective Method of Minimizing
Hauled Liquid Wastes
All d?
• Allowed?
• If not, why not?
If h & d h t diti ?
• If so, how & under what conditions? • How regulated?
T h l i b i f t h l
• Technologies = basis for technology based local limit
Reintroduced Wastewater Solids
Determination for GIs
Example: 30 min Settleable Solids Tests 15 sites
225 ml/L
10.5 ml/L
Town of Cary’s Method for Local
Limit, On-Site GI Maintenance
Followed Pumper throughout the day (8 sites) Followed Pumper throughout the day (8 sites)
Took samples of decant at beginning, middle, end of pumping/treatment operations. Combine end of pumping/treatment operations. Combine each per site
Mimicked daily routine (7-8 per day), 2 daysMimicked daily routine (7 8 per day), 2 days
Imhoff cone settlable test: 95% confidence level that 3ml/L could be achieved. That became
that 3ml/L could be achieved. That became
