5. FOG SAMPLING - InfoHouseinfohouse.p2ric.org/ref/20/19024/19024-5.pdf · FOG sampling from a grease ... the grab sample jar method sat- ... isting data on FOG limits for cat-egorical

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CONSIDERATIONS FOR MANAGEMENT OF THE DISCHARGE OF FOG TO SANITARY SEWER SYSTEMS

5.1 Standard OperatingProcedures

FOG sampling from a greaseseparation device presentsunique and challenging condi-tions. Methods described hereinrepresent an attempt to addressspecific site conditions. Theseguidelines attempt to adhere toprinciples and procedures de-scribed in The Water EnvironmentFederation’s Standard Methods forthe Examination of Water andWastewater and other guidanceprocedures published by EPA.Sample collection protocolswere originally developed bythose agencies to facilitate FOGsample collection in wide chan-nel, weirs, flumes and other non-obstructed areas. Methods 5.2and 5.3 illustrated herein are notto be used for purposes of com-pliance with EPA sampling pro-tocols. All samples are to be col-lected from and should be rep-resentative of wastewater efflu-ent emanating from a greaseseparation device experiencingmaximum hydraulic loading atthe time of sample collection.Sampling for FOG, for compli-ance purposes, is accomplishedby collecting a grab sample(s) ina wide-mouth glass vessel. Allsamples intended for analysisshould be acidified to pH<2.0standard units with sulfuric acidand should be chilled with wetice while in transport to the labo-ratory. Laboratory proceduresfor the receiving and storage ofsamples should be followed.Current EPA and state regula-tions do not provide for transferof sample from collection vessel

to storage/transport vessel. Onlythe grab sample jar method sat-isfies this requirement.

Other methods of FOG samplecollection and equipment clean-ing are presented as alternategrab sample procedures in-tended to approximate the grabsample jar method and shouldnot be utilized for compliancepurposes.

Some methods are presentedherein; figures are for illustrativepurposes and are not to scale.

5.1.1. Grab Sample JarMethod

This method is preferred over allothers listed. When this methodcan be utilized, a wide-mouthcontainer is required.

Equipment:The sample collec-tion jar should be made of glass,stainless steel or Teflon andshould be able to be capped. Theliner of the cap should be Teflon,not paper or plastic. This proce-dure and equipment, althoughnot specifically intended forgrease separation devices, is de-scribed in detail in StandardMethods for the Examination ofWater and Wastewater.

Preparation: Prior to sample col-lection, the jar should be deter-gent washed, double rinsed, fol-lowed by final acetone rinse andallowed to air dry. It should thenbe capped and stored until usage.

Procedure: Insert the sample col-lection jar mouth-first into the

wastewater flow stream. If a hy-draulic jump from the effluentpipe to an invert is present, placethe sample collection jar open-mouthed under the effluentstream and collect the sample.As in all sampling activities, col-lect 1 liter of wastewater sample.The sample should be acidifiedto pH <2.0 standard units withsulfuric acid. The sample con-tainer jar should be large enoughto collect this amount and be ca-pable of being capped for trans-port to the laboratory. Do nottransfer the collected sample toanother holding container in-tended for later analysis. See Fig-ures 5A-5C for illustrations.

5 . F O G S A M P L I N G

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Figure 5A: Sample Vault with Hydraulic JumpPreferred FOG Sample Collection ProcedureUse where sewer main elevation and location

(Illustrative purposes only; designs may vary)

Discharge fromgrease interceptiondevice outlet Hydraulic Jump

Minimum 6”

Sloped toward outletfor complete drainage

Samplevault outletto sewer

Created by:Donald SmithTown of Cary

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Figure 5B: Grab Sample Jar Method 2Sampling Vault Illustration

Sample Vault

8-10” PipeCutout

Flow

1/2” pipe diameter

Concrete fill on both sides ofpipe cutout and sloped tochannel water into pipe.

Sanitary Tee

50% totalwater depth

GreaseSeparationDevice


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Figure 5C: Grab Sample Jar Method 3Sanitary Tee Sample Collection Illustration

(Existing interceptor, where sample vault cannot be installed)

Sample jar attached tosampling rod

GlassSample Jar1,000 ml

Lower SampleJar into Sanitarytee and belowthe flowing waterlevel to obtainsample

4 – 6”sanitary tee

Flow

Grease Separation Device WallInterior Exterior


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5.2 Plunger SampleMethod

The plunger sample is usedwhen a grab sample cannot beobtained using the Grab SampleJar Method.

Equipment: 2-inch diameterStainless Steel Plunge Sampler

Preparation:

1. Laboratory Cleaninga. Cleaning

• Submerge plunger sam-pler into hot soapy wa-ter and scrub using anylon brush

• Rinse sampler threetimes using tap water

• Rinse a fourth and finaltime with deionized ordistilled water

b. Drying• Air dry• Dry with clean paper

towelc. Storage

• Place clean sampler intoa clean plastic bag untilneeded

2. Field Cleaninga. Cleaning

• Wipe down plungersampler using a papertowel to remove any col-lected particles

• Apply methanol to theinner and outer surfacesof the sampler cup andstem; wipe downplunger sampler with aclean wetted papertowel

• Rinse sampler three

times using deionized ordistilled water


towel or clothc. Storage


Procedure:

1. Identify sampling site ascandidate for plunger sam-pler• Use only if sample can-

not be obtained usingGrab Sample Jar Method

• Identify sampling pointon grease separation de-vice

• In order to minimize par-ticle disturbance, do notcheck for or determinesolids or grease layer be-fore sampling

• Completely fill out allchain of custody formsand identification labels

2. Sample• Use a clean plunger sam-

pler or clean the samplerat every site prior to ob-taining sample.

• Make every effort tominimize disruption ofwater at sampling pointso as not to dislodge anygrease that may have ac-cumulated on samplingpoint walls.

• Open the thumb-con-trolled stopper and sub-merge half of the totalcup volume into the

sample collection point.Close the thumb-con-trolled stopper.

• Submerge the plungersample cup and allowthe sample to fill the cupfrom the top until full.

• Remove the samplerfrom the sample pointwith the thumb-con-trolled stopper closed.

• Open the thumb-con-trolled stopper and placesample into a designatedcup for pH and tempera-ture analysis.

• Open the thumb-controlled stopper and sub-merge half of the totalcup volume. Close thethumb-controlledstopper.

• Submerge the plungersample cup and allowthe sample to fill the cupfrom the top until full.

• Remove the samplerfrom the sample pointwith the thumb-con-trolled stopper closed.

• With a clean paper towelwipe any moisture orparticles from the exte-rior of the plungersample.

• Place sampler over anopen and pre-acidifiedclean glass sample jarand open the thumb-controlled stopper,thereby transferring col-lected sample to thetransport container.

• Make sure that the sam-pler does not come intocontact with the interiorwalls of the sample jar.

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• Repeat this samplingprocedure until enoughsample is collected foranalysis. (1 liter)

• Place a sample identifi-cation label on sample jarwith appropriate infor-

mation.• Place sample into a clean

plastic bag and store onwet ice until relin-quished for analysis.

5.3 Bulb ExtractionMethod

The Bulb Extraction Sampler isused when the Grab Sample JarMethod or the Plunger SampleMethod cannot be used to obtaina FOG grab sample due to physi-cal constraints.

Equipment: Stainless Steel BulbExtraction Sampler

Preparation:1. Laboratory Cleaning

a. Cleaning• Remove bulb from sam-

pler tube• Submerse sampler tube

and bulb into hot soapywater and scrub using anylon brush

• Rinse sampler threetimes using tap water

• Rinse a fourth and finaltime with deionized ordistilled water


towel• Storage• Place clean sampler into

a clean plastic bag untilneeded

1. Field Cleaning (betweensample collection events)

a. Cleaning• Wipe down interior and

exterior of bulb extrac-tion sampler using a pa-per towel to remove anycollected particles.

• Apply methanol to theinner and outer surfaces

Figure 5D: Plunger Sampler IllustrationSmall separation devices and sanitary tees

Plunge Sampler


Stainless SteelPlunge Sampler

Vent

Sampler Port

Flow

Discharge toSanitary Sewer


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of the bulb extractionsample bulb and tube.

• Wipe down outer sur-faces of the bulb extractor using a clean papertowel; use a nylon brushto clean the inner sur-faces of the sampler bulband tube.

• Rinse interior and exte-rior of sampler bulb andtube three times usingdeionized or distilledwater.


towelc. Storage


Procedure:1. Identify sampling site as can-

didate for Bulb ExtractionSampler• Use only if sample can

not be obtained usingGrab Sample Jar Methodor the Plunge SampleMethod

• Identify sampling pointon grease separation de-vice

• Do not check solids orgrease layer before sam-pling

• Completely fill out allchain of custody formsand identification labels

2. SampleUse a clean bulb extractionsampler or clean the samplerat every site prior to obtain-ing sample.

• Make every effort tominimize disruption ofwater at sampling pointso as not to dislodge anygrease that may have ac-cumulated on samplingpoint walls.

• Compress bulb on sam-pler prior to placing intosampling point.

• Place collection port ofsampler into sample andrelease compressed bulb,allowing sample to fill

tube.• Release bulb and dis-

charge sample into a des-ignated cup for pH andtemperature analysis.

• Compress bulb on sam-pler prior to placing intosampling point.

• Place collection port ofsampler into sample andrelease compressed bulb,allowing sample to filltube.

Figure 5E: Bulb Sample MethodSmall interceptors

Rubber Bulb

Stainless Steel

Sample Port

Discharge toSanitary Sewer

Flow



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• Use a clean paper towelto remove any moistureor particles collected onthe exterior of the bulbextraction sampler.

• Place sampler over anopen pre-acidified cleanglass sample jar.

• Compress bulb on sam-pler and dischargesample into the samplejar. Make sure samplerdoes not come in contactwith interior walls ofsample jar.

• Repeat sampling proce-dure until enoughsample is collected foranalysis.

• Place a sample identifi-cation label on sample jarwith appropriate infor-mation.

• Place sample into a cleanplastic bag and store onwet ice until relin-quished for analysis.

5.4 Analyzing Samples

Until recently, the standardmethod for measuring FOG wasEPA Method 413.1 or Method5520 B, Standard Methods forthe Examination of Water andWastewater. This method usesFreon and is being phased outin order to meet the chlorofluo-

rocarbon (CFC) phaseout re-quired in the 1990 Clean Air ActAmendments. Much of the ex-isting data on FOG limits for cat-egorical industries is based onthis method. The new EPA-ap-proved method is Method 1664.This new method uses n-Hexaneand has similar, but not exactlythe same results, as n-Hexanevalues run about 23 percentlower than Freon values. (Re-sults are based upon compara-tive analyses conducted by theTown of Cary as illustrated inFigure 5F). In addition, the n-Hexane method is more laborintensive, but the average pricefor analysis is similar.

Figure 5FTown of Cary: Method 413.1 vs. Method 1664 study, 2000 - 2001

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Method 1664Method 413

Median difference between methods: method 413.1 (Freon based) extracts animal/vegetable FOG approximately 23% better than method 1664 (n-Hexane based).

Documents

5. FOG SAMPLING - InfoHouseinfohouse.p2ric.org/ref/20/19024/19024-5.pdf · FOG sampling from a grease ... the grab sample jar method sat- ... isting data on FOG limits for cat-egorical