8 Honolulu Wastewater System Number of Treatment PlantsNumber of Pump StationsTotal Design Flow (mgd)872120Collection System - approximately 2,000 miles of sewer linesHonolulu population is about 800,000.
9 Compliance Background 1982 Honolulu’s Pretreatment Program Approved by EPA1990 EPA issues Findings of Violations to Honolulu (related to SSO’s)1995 Honolulu enters into Consent Agreement with EPA1999 GI retrofit program begins; 90 grease related SSO’s = 36% of total annual SSO’s.% of facilities retrofitted; 46 grease related SSO’s = 23% of total annual SSO’s.
10 Collection System Maintenance & Historical Data
11 Collection System Maintenance Infrastructure Efforts to control FOGRepair collection system conditions which promote grease blockages (e.g. line sag, surcharge conditions, pipe cracks/breaks, root intrusion).Modify collection system standards to accommodate grease (e.g. seamless pipe, increased slope, larger pipe).Conduct effective preventive maintenance program (i.e. identify and target “hot spots”).Report chronic FOG problem areas or dischargers to the Pretreatment Program for enforcement.Maintain detailed and accurate records of system condition.
12 Collection System Historical Data Areas with Low Percentage of Retrofitted GIsLOCATION1999200020012002% of GIs upgraded% of records indicating heavy grease in lineKALAKAUA0%12%67%100%KAPIOLANI4%9%92%82%AUAHI5%11%ALA MOANA6%Approximately 20% of businesses requiring a GI have been retrofitted.
13 Collection System Historical Data Areas with Higher Percentage of Retrofitted GIsLOCATION1999200020012002% of GIs upgraded% of records indicating heavy grease in lineBERETANIA0%12%21%96%100%23%22%KAM HWY10%15%20%75%50%KALAKAUA5%25%8%33%84%80%35%14%Approximately 20% of businesses requiring a GI have been retrofitted.
14 Collection System Historical Data Pipe Cleaning and Spill Records:YearMiles of Pipes CleanedNumber of Wastewater SpillsNumber of Grease Related Spills *Grease Spills as a Percentage of Total Spills19953432687327%19964063329529%19974013108828%19985582316327 %1999 **8912529036 %20006582638633 %200167524030%20027071994623%* Grease was primary cause of spill** Began GI retrofits in June (20% Complete)
15 Collection System Historical Data Sand Island WWTP Data:YearFlow (mgd)Influent O&G (mg/l)Grease Spills199575.93544.273199675.62337.295199777.04727.788199873.46228.5 *63199973.91722.590200072.65425.386200170.66424.5200269.55924.246Reduction %10%45%48%* O&G analytical method changed from to 1664A (freon to hexane) in November 1998, as well as, new NPDES permit required increased monitoring frequency from 1/week to 3/week.
17 Pretreatment Program Research Findings: Many Fats, Oil and Grease (FOG) Sources are Not Connected to a GI (Pre-rinse garbage disposals).Existing Grease Interceptors (GI) are “Inadequate”.How do you determine what is adequate?
18 Consider…Stokes’ Law: Pretreatment ProgramConsider…Stokes’ Law:Vr = g/18ν [S.G.w – S.G.o] x D²Where:Vr – rising velocity of the oil particle (cm/sec)g – gravity constant (980 cm/sec²)ν – viscosity of water in poises (0.01)S.G.w – specific gravity or density of water (gm/cm³)S.G.o – specific gravity or density of oil (gm/cm³)D - diameter of the oil droplet (cm)
19 Factors Affecting FOG Separation: Pretreatment ProgramFactors Affecting FOG Separation:Temperature – the less viscous the fluid (higher temp.), the faster the particle rise rate. However, too high temp. promotes emulsification.Specific Gravity - The greater the differential specific gravity or density between the fluid and the particle, the faster the rise rate.Diameter – The larger the particle diameter the faster the particle rise rate.
20 Oil Globule Rise Times for 3 inches @ 68 F: Pretreatment ProgramOil Globule Rise Times for 3 68 F:Diameter[microns]Rise Time (S.G.=0.9) [hr:min:sec]3000:00:151250:01:27600:06:36400:14:24200:58:0810 (colloidal)3:52:331387:35:49Table info from American Petroleum Institute Publication FOG S.G. range =
21 Pretreatment Program Retention Time Does Size Matter?? YEAH BABY, YEAH!!Grease Interceptors must be sized to promote the adequate separation of FOG from wastewater. An important factor to consider is………..Retention Time
22 Pretreatment Program GI Sizing Criteria Minimum Grease Interceptor Volume (Vmin) isdetermined using Retention Time (R), StorageFactor (S) and Flow Rate (F).or, V(min) = R x S x FR = 30 MinutesS = (25% Allowance)F = Maximum Flow Rate Entering the GI (gpm)where,
23 Pretreatment Program GI Sizing Criteria V (min) = 30 x 1.25 x FF - Flow rate is determined based on Drainage Fixture Units (DFU)
24 Pretreatment Program GI Sizing Criteria Flow RateNo. of Drainage Fixture Units 40* F = (0.7 x DFU)No. of Drainage Fixture Units 40* F = (0.2 x DFU) + 20DFU’s based on the Uniform Plumbing Code, 1997 edition, Table 7-3: Drainage Fixture Unit Values, Section Maximum Trap Loading, or Table 7-4: Discharge Capacity (gpm) for Intermittent Flow Only.* “Piping Handbook, 7th Edition”, Muhinder L. Nayyar, McGraw-Hill;Tables C13.3 & C13.4 on pages C.690 & C.691.
25 Hotel with Kitchen and Restaurant Pretreatment ProgramComparison of Grease Interceptor Sizing CriteriaUPC Appendix H1999 Honolulu Criteria(Denver Based)2001 Honolulu CriteriaType of FacilityCalculated SizeTank RequirementChinese Restaurant6,0002 x 3,0001,1251,5008851,000Seafood Restaurant2,0883,0001,080Fine Dining16,5003 x 5,000 +3,2754,0001,390Hotel with Kitchen and Restaurant3,5001,6882,0001,050Dinner Theatre (Luau)7,5002 x 4,0002,500919Large Restaurant10,3202 x 5,000 +3,2252,520Medium Restaurant2,1001,5311,208Small Restaurant375500750456
26 HONOLULU SIZED GREASE INTERCEPTOR Pretreatment ProgramHONOLULU SIZED GREASE INTERCEPTORSAMPLING RESULTSNumber of GIs sampled - 45Number of samples taken - 90Average Oil & GreaseEffluent Concentration (Avg) mg/lpH (min) (avg) (max) 7Temp. (degrees F) (min) 69º (avg) 86.6º (max) 105º(Melting Point of Tallow (i.e. animal fat) degees F)
27 Pretreatment Program GI Maintenance Requirements 25% RULEStorage factor used to determine GI maintenance frequency consisting of surface FOG material and settled solids.PUMP-IN-FULLInsure all solids are removed.Inspect the GI for corrosion damage or cracks.Enables “cradle-to-grave” tracking of FOG waste.
29 FOG Control Success Factors Consistent Facility Compliance EvaluationsPersistent/Consistent Enforcement ActionsPlan Reviews to verify Compliance with GI ProgramDatabase Tracking and Follow-upProgram Implementation StrategyEconomic ConsiderationsPublic Outreach and Education
30 FOG Control Success Factors Program Implementation Strategy!Understand the Political Environment – Votes.Understand the Media – Stay 2 steps ahead. Create a “No Story” situation.Involve the Industry – Raise awareness by meeting with Stakeholders (Property Owners, Restaurant Owners, Area Organizations/ Committees, Trade and Business Associations, City and Elected Officials).Think “Money” - Businesses focus is on $. Find a way to merge environment and regulations. Build partnerships with the “Big Dogs”.
31 FOG Control Success Factors Economic Considerations:Project coordination & funding by property owners:Property owners and tenants equally liable under most Ordinances.Owners finance improvements and renegotiate tenant leases.Tenants pay only their fair share while they are there.Shared Grease InterceptorsMixed Waste (kitchen/domestic) Grease Interceptors. [Currently 2 operating in Hawaii with more proposed]Grant easements where space is limited.ADDITIVES - Biologicals Only…No Enzymes or Surfactants.
32 FOG Control Success Factors Public Outreach and EducationPublic Info Meetings, Community/Industry EventsBrochures, Bus PostersEducational Videos/Public Service Anouncements (Show Video)