How to do Stormwater SamplingA guide for industrial facilities

Washington StateDepartment of Ecology

December 2002 (rev. March 2010)

Publication #02-10-071

The Department of Ecology is an equalopportunity agency and does not discrim-inate on the basis of race, creed, color,disability, age, religion, national origin,sex, marital status, disabled veteran'sstatus, Vietnam Era veteran's status, orsexual orientation.

To ask about the availability of thisdocument in a version for the visuallyimpaired, call the Water Quality Programat 360-407-6401. Persons with hearingloss, call 711 for Washington RelayService. Persons with a speech disability,call 877-833-6341.

Acknowledgements

The Water Quality Program wouldlike to thank the following individu-als for contributing their hard workand technical knowledge to the 2010update.

From the Department of Ecology:Jeff KilleleaStephen GoldingElaine TomitaJulie LoweDewey WeaverKurt BaumgartenKevin HancockMarc PacificoTom Leonard

From EnvironmentalCompliance Tools LLC:Robin Sandell

Table of Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 1

Advance Planning for Stormwater Sampling . . . . . . . . . . . . . . page 2

Deciding What To Sample . . . . . . . . . . . . . . . . . . . . . . . . . . . page 2Visible Oil Sheen, Zinc, Copper, Turbidity, and pH . . . . . . . . . . . . page 2Selecting a Laboratory to Test Your Sample . . . . . . . . . . . . . . . . . page 2Contacting the Lab in Advance . . . . . . . . . . . . . . . . . . . . . . . . page 3Issues you may want to cover with the lab include: . . . . . . . . . . . . page 3Deciding How You Will Take The Sample . . . . . . . . . . . . . . . . . page 4Collecting Total Petroleum Hydrocarbons (TPH)Samples . . . . . . . . page 5Determining which Discharges to Sample . . . . . . . . . . . . . . . . . page 5Selecting Sampling Points . . . . . . . . . . . . . . . . . . . . . . . . . . . page 7Obtaining Supplies for Sampling. . . . . . . . . . . . . . . . . . . . . . . page 8

Planning Just Prior to Stormwater Sampling . . . . . . . . . . . . . page 9

Being Prepared. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 9Choosing When to Sample . . . . . . . . . . . . . . . . . . . . . . . . . . . page 9Check weather forecasts. . . . . . . . . . . . . . . . . . . . . . . . . . . . page 10

Conducting Sampling at Your Facility . . . . . . . . . . . . . . . . . page 11

Checklist for Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 11How to Fill Sample Bottles . . . . . . . . . . . . . . . . . . . . . . . . . . page 11Keeping Records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 12When the Sampled Storm Doesn’t Meet the Required Criteria . . . . . page 13

Special Sampling Considerations . . . . . . . . . . . . . . . . . . . . page 14

Sampling as Stormwater Discharges from a Pipe into a Receiving Water . . page 14Sampling from a Manhole . . . . . . . . . . . . . . . . . . . . . . . . . . page 14Sampling from a Drainage Ditch or Swale . . . . . . . . . . . . . . . . . page 15Sampling Sheet Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 15Sampling from a Stormwater Detention Pond or other BMP . . . . . . page 16

Ecology Wants to Hear from You . . . . . . . . . . . . . . . . . . . . page 17

Appendix - Proper and Improper Methods of Sampling . . . . . . . page 18

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Inside back cover

Introduction

The Industrial Stormwater GeneralPermit requires that your facility

conduct at least quarterly sampling ofstormwater and report the samplingresults to Ecology. These require-ments are outlined in the permit un-der Section S4. General SamplingRequirements. This guide supportsthe sampling portion of the generalpermit but does not substitute for it.

The purpose of this guide is to helpthose who operate facilities do theirown sampling by describing the stepsand procedures to be followed. Thisguidance will lead you to be able tosample in a way that will provide youand Ecology with meaningful results.

Sources of pollutants that may en-ter surface water, sediments, orground water can be identified bysampling stormwater discharges. Theresults of sampling will be helpfulwhen developing your StormwaterPollution Prevention Plan (SWPPP),

determining if your existing plan isadequate, and when implementing orassessing best management practices(BMPs).

Some effort is required up front toprepare for sampling in a way thatwill meet requirements and provideuseful data. What follows is a step-by-step procedure of what you needto do to gather and report data thatwill represent the quality of storm-water leaving your facility. The stepsare organized to guide you throughthe stormwater sampling processfrom start to finish.

This guidance is an update to“How to do Stormwater Sampling”which was originally developed byEcology’s Environmental AssessmentProgram in 2002. The update was madein accordance with the new IndustrialStormwater General Permit which be-came effective on January 1, 2010.

Page 1 Introduction

The purpose of this

guide is to help

those who operate

facilities do their

own sampling.

Advance Planning forStormwater Sampling

Deciding what to SampleBefore beginning your sampling, you’llneed to determine the specific pollutants(water quality parameters) you are re-quired to sample and test for. All facili-ties must monitor for turbidity, pH, zinc,copper, and the presence of a visible oilsheen. Your parameters are based on:

�The standard set of parameters forall facilities, (turbidity, pH, zinc,copper and visible oil sheen).

�The industrial activities at yoursite, often classified by your facility’sStandard Industrial Code (SIC Code).

�Whether your facility discharges toan impaired (303 (d) listed) waterbody.

�Any requirements that apply tofacilities that discharge to water bodieswith a water cleanup plan or TotalMaximum Daily Load (TMDL).

Ecology has listed the required parame-ters for your facility on your DischargeMonitoring Report (DMR) form.

Visible oil sheen, zinc,copper, turbidity, and pHIf there is a visible oil sheen at the point ofdischarge from your facility, you need tomake note of it on your DMR form. Arainbow colored sheen on the surface ofstormwater may indicate the presence ofoil. However, not all sheens on the waterare oil sheens. Some sheens result fromnatural processes, such as rotting vegeta-tion or the bacterial breakdown of iron.How do you tell the difference betweenan oil sheen and a naturally occurringsheen? Try to break up the sheen with astick. An oil sheen will swirl, elongate,and reform. A sheen resulting from a nat-ural process will typically break up intoirregular platelets that do not reform andhave a mirror-like appearance.

Turbidity can be measureddirectly in the field using a handheldmeter, or sampled and analyzed inthe lab. You must measure pH inthe field using either a calibrated pHmeter or pH paper rather than send-ing it to a lab. This is due to the shortholding time for pH. You can getpH paper from a distributor of scien-tific/laboratory supplies or throughthe same laboratory that will be doingyour sample analysis. Zinc, copper,and other parameters required by thepermit (other than turbidity and pH)are measured by sending bottled sam-ples to a laboratory for analysis.

Selecting a laboratoryto test your sampleHaving identified the parameters youwill need tested, the next step is to se-lect a laboratory to perform the tests.You are required to select a lab ac-credited by Ecology. The lab must beaccredited for each analytical methodrequired by the permit for each pa-rameter. Accreditation assures Ecol-ogy that the lab is able to do qualitytesting using the analytical methodsspecified under Monitoring Require-ments in your permit. You can searchfor an accredited lab on Ecology’swebsite: www.ecy.wa.gov/ programs/eap/labs/search.html

Advance Planning for Stormwater Sampling Page 2

All facilities must

monitor for

turbidity, pH, zinc,

copper, and a

visible oil sheen.

This is an

example of an

oil sheen at a

storm drain

Contact the lab

well ahead of time.

Contacting thelab in advanceYou should contact the lab well aheadof time. They will be providing youwith the sampling bottles you’ll need.For some water quality parameters,such as Total Petroleum Hydrocarbons(TPH), it is not only desirable but nec-essary to collect the sample directlyinto a specially-cleaned container, soyou will need to have bottles from thelab on hand before you sample. Youcan also ask your lab to send narrow-range pH paper (with a resolution notgreater than ± 0.5 SU) along with yoursample bottles.

Please note that not all facilitiesare required to collect TPH samples.Refer to page 26 of the permit for alist of industrial activities for whichthe permit requires TPH samples.

Discuss with the lab the analyticalmethods they will use, as specified inthe sample parameter tables includedin S5. A and S5. B of the generalpermit (pages 24 and 25). The lab willprovide you helpful information andexplanations that go beyond thescope of this guide. If you must meeteffluent limits listed in “S5.C, Storm-water Discharges Subject to EffluentLimitation Guidelines” you shouldcarefully review them with the lab.

Issues you may want to coverwith the lab include:�Confirmation that the lab isaccredited for the testing methods thepermit requires.

�The type and size of bottle that willbe supplied for each water qualityparameter to be sampled and tested.

�How full to fill the bottle.

�Any safety concerns with materialssupplied by the lab.

�What you need to know aboutpreserving your samples: Make a noteof the parameters for which bottles willhave preservative inside. For some tests,a preservative is necessary. Thepreservative is a substance that stabilizescertain chemicals at the time of samplingso that a valid test can be done later. It iscritical that you use the correct bottlesbecause tests requiring preservative willnot be valid without the correctpreservative. In some cases, the wrongpreservative will interfere with a test. Itis important not to lose the preservativethat comes in the bottles supplied by thelab. The table to the left providesinformation for preserving zinc,turbidity, and copper samples.

�The kind of labels the lab willsupply for the bottles and how thelabels should be filled out. The labelsor tags you use to identify thesamples you take must be waterproof,and if you write on them, the writingmust be waterproof also.

�Get a Chain of Custody (COC)form from the lab and go over how tocomplete these before sampling thefirst time.

�A description of forms or otherpaperwork to submit to the lab withthe samples and how to fill them out.

�Whether the lab will supply pHpaper as well as sample bottles, tags orlabels for the bottles, and blank forms.

�How bottles and other suppliesfrom the lab will be delivered to you.

Page 3 Advance Planning for Stormwater Sampling

Parameter Bottle TypeMinimumSampleRequired

HoldingTime

Preservation

Turbidity500 mL wide-mouthed poly

100 mL 48 hours Cool to 4º C

Total Zinc

1liter (L)bottlecleanedaccording toprotocol

500 mL 6 monthsHNO3 to pH<2

Cool to 4º C

Copper,TotalRecoverable

500 mL HDPEDependenton the lab

6 months HNO3 to pH<2

Typical Sampling Information

Ask questions -

your lab can

help you.

�The holding times for each waterquality parameter to be sampled andtested. A holding time is themaximum time allowed betweentaking the sample and doing the labanalysis. If you exceed holding time,the sample analysis is not acceptable.

�How and when you will deliversamples to the lab. Plan with the labhow you will get the samples to themin time to begin analysis before theparameter with the shortest holdingtime reaches that holding time. Thefastest way to deliver samples to thelab may be in person, but it may bepossible to ship samples (cooled inpicnic coolers) and still meet holdingtimes. If you deliver samples inperson, you can pick up bottles andsupplies for the next quarter at thesame time. The table (page 3) showstypical sampling information for thethree water quality parameters thatmust be monitored under theIndustrial Stormwater GeneralPermit. The information you obtainfrom your lab may differ from this. Inmany cases, the preservatives listed inthe table come pre-measured in thesampling bottles and there is no needto check pH. Ask your lab about this.

�How to read the lab reports for thesample results. Sampling requirementstend to use scientific words and units ofmeasure. Temperature is measured indegrees Celsius, “C”. Typical UnitedStates thermometers measuretemperature in Fahrenheit, “F,” and4º C is about 39° F. For your purposes,“Cooling to 4º C” means putting thesamples on crushed ice or packed withblue ice in an ice chest so they will bekept just above freezing. Metric unitsare used to measure weight, volumeand distance. Liquid volumes use liters,“L” and milliliters, “mL,” not “quarts”and “cups”. Chemicals have their ownscientific notation. Nitric acid forexample is HNO3. Be sure to have thelab explain any words or expressionsthat you do not understand.

Deciding How You WillTake The SampleSection S4.B.1(d) on page 22 of theIndustrial Stormwater General Permitstates that a grab, time-proportionate,or flow proportionate sample maybe taken. A grab sample is a singlesample “grabbed” by filling up acontainer, either by hand or with thecontainer attached to a pole. It is thesimplest type of sample to collect andit is expected that most permit holderswill choose to collect grab samples.Ecology provides standard operatingprocedures (SOP) for obtaining grabsamples, along with other samplingguidance, at http://www.ecy.wa.gov/programs/eap/quality.html.

As we will discuss in the next sec-tion, Total Petroleum Hydrocarbons(TPH) samples must be collected asgrab samples. Some permit holdersmay choose to better represent waterquality parameters other than TPH bycollecting time-proportionate or flow-proportionate samples. These sam-ples consist of a number ofsubsamples taken at intervals ratherthan a single grab sample. Time-pro-portionate or flow-proportionate sam-pling can accurately define pollutantloading during various times of dis-charge throughout a storm event anddetermine whether or not higher pol-lution is occurring during first flushof the storm.

A time-proportionate sample is onemade up of a number of small samples(subsamples) of equal volume col-lected at regular time intervals com-bined into a single large sample. Aflow-proportionate sample is onemade up of a number of subsampleswhere each subsample is collected insuch a way as to represent a givenamount of stormwater discharge.Time-proportionate and flow-propor-tionate samples provide the advantageof including a number of smaller sam-ples (subsamples) in the sample so thatthe stormwater discharge is better

Advance Planning for Stormwater Sampling Page 4

represented than with a grab sample.Time-proportionate and flow propor-tionate samples can be collected eitherby hand or with automated equip-ment. Automated equipment canprovide unstaffed sample collectionoutside of normal business hours.Additional information regardingrequirements for automated storm-water sampling is available online athttp://www.ecy.wa.gov/programs/eap/qa/Agency/ECY_SOP_AutomatedSampling_v1_0.pdf. Collecting time-proportionate or flow-proportionatesamples by hand is somewhat difficultand collecting them with automatedequipment involves additional ex-penses, such as the installation of aflow meter for automated sampling.

Collecting total petroleumhydrocarbons (TPH) samplesIn addition to the requirement for allpermit holders to monitor for a visibleoil sheen, the general permit requiresthat facilities with the following indus-trial activities and Standard IndustrialClassification (SIC) codes collect TPHsamples: Primary Metals(33xx), MetalsMining (10xx), Automobile Salvage andScrap Recycling (5015and 5093), MetalsFabricating (34xx), Hazardous WasteTreatment, Storage and Disposal Facil-ities and Dangerous Waste Recyclerssubject to the provisions of ResourceConservation and Recovery Act(RCRA) Subtitle C. Because of theparticular way TPH samples must becollected, this requirement may governyour overall approach to sampling.

For some parameters other thanTPH, it is possible to sample in difficultsituations by filling a container andtransferring it to the sample bottle to besent to the lab. TPH samples, however,must be collected from the stormwatersource directly. The sample cannot betransferred from another container be-cause oil and grease tends to stick to theinside surfaces of containers. Since youmust sample directly into the TPH bot-

tle (grab sample), taking grab samplesmay be the easiest way to collect addi-tional samples for the other parameters.Take samples by collecting stormwaterdirectly from the discharge into thebottles supplied by the lab, filling eachbottle one after another.

Because TPH samples cannot betransferred between containers, a sam-ple cannot be formed from separategrab samples combined together. Ifmore than one TPH sample is desiredfrom a sampling site during a stormevent, additional TPH grab samplesmust be collected and analyzedseparately.

Because TPH samples must becollected directly and not through thetubing of an automatic sampler, thoseusing automatic samplers will stillhave to grab TPH samples by hand.This is also true for facilities that mustsample for fecal coliform.

Determining whichdischarges to sampleThe first step in selecting samplingpoints is to consider the areas drain-ing your facility. The site map in yourSWPPP should show the drainage ar-eas. Areas of particular concern arethose where raw materials or finishedproduct are exposed to rainfalland/or runoff, and areas where leak-ing fluids such as petroleum productsand hydraulic fluids have the poten-tial to enter stormwater runoff.

The next step is to determinewhere the runoff from each drainagearea is discharged from your facility.If there are separate drainage areaswith separate discharge points,stormwater sampled at one dischargesampling point may not represent thefacility’s stormwater quality overall.

Section S4.B.2 on page 22 of theIndustrial Stormwater General Permitdescribes the requirements for select-ing sampling points:

Page 5 Advance Planning for Stormwater Sampling

Practice sampling

before you do

the real thing.

Total Petroleum

Hydrocarbons (TPH)

samples must be

collected directly

into the bottle you

send to the lab.

S4.B.2. Sample Location(s)

�The Permittee shall designatesampling location(s) at the point(s)where it discharges stormwaterassociated with industrial activityoffsite.

�The Permittee is not required tosample onsite discharges to ground(e.g., infiltration, etc.) or sanitarysewer discharges under this permit,unless specifically required byEcology (Condition G12, page 45).

�The Permittee shall sample eachdistinct point of discharge offsiteexcept as otherwise exempt frommonitoring as a “substantiallyidentical outfall” per S3.B.5.b (pages20 and 21). The Permittee is requiredto monitor only one of the“substantially identical outfalls” iftwo or more outfalls dischargesubstantially identical effluents(based on similar industrial activitiesand site conditions).

�The exception to sampling eachpoint of discharge in S4.B.2.c (page 22)does not apply to any point ofdischarge subject to numeric effluentlimitations as described in ConditionsS5.C (page 27), S6.C (pages 30 and 31),and S6.D (pages 32 and 33).

As a general matter, your stormwaterdischarge samples will be takenwhere your facility’s stormwater isdischarged offsite. If your facility dis-charges stormwater collected over ar-eas that are used for similar activitiesand have similar site conditions, andthere is reason to believe pollutanttypes will be similar in such areas, asingle sampling point can be used torepresent several discharge points.The Industrial Stormwater GeneralPermit allows you to sample at onlyone outfall when multiple outfalls atyour facility have similar industrialactivities, best management practices(BMPs), exposed materials, and im-pervious surfaces that could affectstormwater percolation into the

ground. Outfalls that have thesesimilar characteristics are called “sub-stantially identical outfalls,” and youare required to monitor only one ofthe “substantially identical outfalls”rather than all of them. Refer to Con-dition S3.B.5 on pages 20 and 21 ofthe permit for how to determine if the“substantially identical outfall” ex-ception applies to some of your dis-charge points, and be sure that yourSWPPP includes documentation ofhow sampling locations were chosen.

If your facility has multiple dis-charge points from areas with differ-ent industrial activities, BMPs,exposed materials, or impervious sur-faces, the discharge points would notbe considered substantially identicaloutfalls, and therefore you wouldneed to sample all of the outfalls. Forexample, if one portion of the site isused to store raw materials and dis-charges separately from another por-tion of the site where vehiclemaintenance (e.g., fueling, lubrica-tion, etc.) takes place, the stormwaterdischarge points would not be sub-stantially identical and both dischargepoints would need to be sampled.

Making a determination ofwhether some of your dischargepoints can be considered “substan-tially identical outfalls” would requirecareful consideration of ConditionS3.B.5.b of the Industrial StormwaterGeneral Permit. If you determine thatsome of your discharge points do notneed to be sampled, the Sampling Planin your SWPPP needs to include docu-mentation of why each discharge pointis not sampled per Condition S4.B.2.c,including:

a) The location of which dischargepoints the Permittee does not samplebecause the pollutant concentrationsare substantially identical to a dis-charge point being sampled.

b) General industrial activities con-ducted in the drainage area of eachdischarge point.

Advance Planning for Stormwater Sampling Page 6

Take time to

get ready for

sampling.

c) Best management practices con-ducted in the drainage area of eachoutfall.

d) Exposed materials located in thedrainage area of each discharge pointthat are likely to be significant contri-butors of pollutants to stormwaterdischarges.

e) Impervious surfaces in the drain-age area that could affect the percola-tion of stormwater runoff into theground (e.g., asphalt, crushed rock,grass, etc.).

f) Reasons why the Permittee expectsthe discharge points to discharge sub-stantially identical effluents.

Selecting sampling points�Pipes discharging your facility’sstormwater offsite.

�Ditches carrying your facility’sstormwater offsite.

�Manhole access to storm sewerscarrying your facility’s stormwater, soyou can lower a sample bottleattached to a pole into the manhole.In general, manhole access on yourproperty may be simpler and saferthan access off property and morereadily verifiable as carrying onlyyour facility’s stormwater.

These three types of sampling pointsare usually not too difficult to accessand the flow within them tends to befast enough, with enough turbulence,to allow you to collect well mixed,representative samples. In some cases,portions of industrial stormwater run-off leave a site as sheet flow. Specificapproaches to sampling of pipes,ditches, manholes, grated storm drains,and sheet flow will be covered in thefinal section of this guide manual.

Make sure your sampling pointswill provide for sampling only thestormwater that comes from your facil-ity. If the stormwater in a pipe (stormsewer) contains other discharges, moveyour sampling point upstream to a

point where the flow is from your facil-ity only. Also check to see that there isno base flow in the storm sewer duringdry periods. Report in your SWPPP thepresence of any base flow and measureor estimate its flow rate. If it is not pos-sible to sample only flow from your fa-cility, document the reason for this andprovide information concerning thesource of the flow you are sampling.

If possible, the stormwater your fa-cility samples should not be a mixtureof your facility’s stormwater with otherwater. Some examples of situationswhere a sample would be of a mixtureof water sources, and you should notsample are listed below:

Examples of mixed water sourcessituations in which you should notsample:

�A ditch that carries additionalstormwater from propertiesupstream. In this case, the stormwaterfrom your facility is mixed with otherwater and you should find a locationor locations where only your facility’sstormwater can be sampled.

�A stormwater sewer or pipe (culvert)discharges to a creek or other receivingwater, the pipe being partiallysubmerged where it discharges into thereceiving water. In this case, this finaldischarge point will not be able to beused as a sampling point because thestormwater flow is mixed with thereceiving water.

�A manhole that carries stormwater,not only from your facility but fromother stormwater sources as well. If youare grabbing a sample from a manholebut from the point where a storm sewerfrom your facility ends at a municipalmanhole, make sure that the flow inthat pipe is entirely from your facility,that the pipe is not submerged or partlysubmerged and that you are otherwisenot prevented from collectingstormwater from your facility only. Ifyou are not sure that a storm sewercarries only flow from your facility, the

Page 7 Advance Planning for Stormwater Sampling

Manhole access can

be a good sample

point if it can be

accessed safely and

the stormwater is

solely from your

facility. Do not

climb into the

manhole. Use a

sample bottle

attached to a pole

to take the sample.

Base flow here

refers to any water

in the ditch that is

not a direct result

of stormwater

runoff. Ground

water seepage into

the ditch, for

example, would add

base flow.

municipality may have storm sewerplans to help you determine this.Contact the municipality beforehand todiscuss sampling from the manholeand associated safety issues,particularly for manholes in areaswith vehicular traffic.

It is important to sample flow fromonly your facility if possible becauseotherwise it cannot be determinedwhat the sample actually represents. Ifyou discharge stormwater to a storm-water conveyance system that includesstormwater from other sources, youneed to sample before your storm-water commingles with stormwaterfrom other sources. However, if storm-water runs onto your property in anuncontrolled fashion (for example,sheet flow) from adjacent property,into areas of industrial activity on yoursite so that it becomes a part of thestormwater discharge from your site,this should be included in your sampleof stormwater discharge. If you areconcerned about this offsite source,you may want to sample that storm-water where it enters your property. Ifthe results show significant pollution,you may want to provide Ecologywith a narrative description of the con-tributing site and sample results todocument the relative contribution ofthe other property or upstream source.

It is a good idea to observe thesampling point(s) you have chosenduring actual stormwater runoff con-ditions to see how readily stormwatercan be sampled there. Keep in mindthat changing tides and flow condi-tions in receiving waters, includingflood stages may occur during stormevents. This may cause a pipe that isdischarging your facility’s storm-water to become submerged or partlysubmerged, preventing you fromsampling during some conditions.

Obtaining suppliesfor samplingThe supplies you will want to haveon hand before sampling include:

�Sampling bottles from the lab,including a few extra of each type.

�When needed, a pole to holdsample bottles and filament strappingtape.

�Powder-free disposable nitrile orlatex gloves . These are sold bymedical and laboratory suppliers. Donot use powdered gloves as thepowder may contain metals thatcould contaminate metals samplessuch as zinc.

�Foul-weather gear.

�One or more coolers, depending onthe number of samples to be storedand transported or shipped.

�A bound notebook to serve as afield book for keeping recordsconcerning sampling. Notebooks withwaterproof pages are available forthese field notes at office supplystores. The information to be includedin the notes will be described in the“Keeping Records” section of thisguide. You may find it helpful tocreate a standardized form containingthe information in this as well.

Advance Planning for Stormwater Sampling Page 8

Planning Just Prior toStormwater Sampling

Now that the bulk of the planningfor sampling is complete, there are

a few things to keep in mind beforedeciding to actually begin sampling.

Being prepared

It is important to assemble every-thing that will be needed for the

sampling event ahead of time becauseopportunities to sample during stormevents often come with little advancenotice. Complete the identificationtags and Lab Services Required form.Place the tags, lab form, field note-book, permanent ink pen, meter, andpH paper in the cooler with the sam-ple bottles. Have resealable plasticbags or other means on hand to keepthe pH paper dry. If you are usinga turbidity meter or pH meter, beprepared to protect them from therain. Have foul-weather gear readyand available. It will be necessary tokeep sufficient ice onsite or plan topurchase ice that day.

Choosing when to sampleThe permit requires that you samplethe discharge from each designatedlocation at least once per quarter:

�1st Quarter =January, February, and March

�2nd Quarter =April, May, and June

�3rd Quarter =July, August, and September

�4th Quarter =October, November, and December

You will need to sample the “first fallstorm event” each year. The permitdefines the “first fall storm event” asthe first time after October 1st thatprecipitation occurs and results in astormwater discharge from thefacility. Please note that you are notrequired to sample storm events thatoutside of normal business hours orin unsafe conditions.

Collect samples within the first 12hours of stormwater discharge. If you

Page 9 Planning Just Prior to Stormwater Sampling

Sample during the

first 12 hours of a

stormwater

discharge

are not able to collect a sample withinthe first 12 hours, collect the sampleas soon as possible. In the samplingrecords, keep documentation explain-ing why you could not collect sam-ples within the first 12 hours.

If your facility is located in an areathat is covered by a standing snowpack for days at a time during a yearof normal precipitation, you may al-ternatively sample a snowmelt eventduring the winter or spring quarter.

Check weather forecastsKeeping up with the weather forecastand planning so that sampling can becarried out on short notice are thekeys to successful sampling.

Local forecasts, including televisedsatellite and radar images can give anindication of the expected intensity ofcoming storms. The National WeatherService is an excellent source of infor-mation on upcoming storms. It alsoincludes local current radar and satel-lite images. Their website is:http://www.wrh.noaa.gov/index.php.

A number of commercial websites,such as http://www.weather.com/ andhttp://www.accuweather.com/ alsoprovide weather information andforecasts.

When evaluating a weather fore-cast, consider indications of expectedintensity, for example “90% chance”rather than “30% chance” and “rain”rather than “showers.” Over the tele-phone, National Weather Service per-sonnel can often provide estimates ofanticipated rainfall amounts. In addi-tion to intensity, consider the pre-dicted duration of the storm. It will bevery helpful to spend time observingrain events at your site with attentionto how rain intensity relates to storm-water discharges from your site, be-fore you begin sampling.

Once the decision has been madeto attempt to sample a storm event,the personnel who will be samplingshould be notified and they shouldprepare to sample. If it does rain, theyshould be at the sampling sites beforestormwater begins discharging sothey can document the time of dis-charge and be ready to sample.

Planning Just Prior to Stormwater Sampling Page 10

Take notes!

Writing down

your observations

at the time of

sampling is

important.

Conducting Sampling at Your Facility

After you have selected a stormevent and it begins raining, the

personnel conducting the samplingshould prepare their equipment andgo to the sampling site(s). They willbe collecting grab samples at the sam-pling site(s), placing the samples inpicnic coolers containing ice, andkeeping notes in a field book. Sam-pling for the first time may requireworking out some difficulties, but af-ter performing these duties once, fu-ture sampling will not be as difficult.

Checklist for samplingBecause stormwater sampling is not adaily part of the workload of a facility,it is a good idea to keep a checklist ofthings to have prepared before sam-pling and to do during sampling. Youcan make the checklist by jotting downthe things you did for the first samplingevent to remember for subsequent sam-pling events. If necessary, update thischecklist based on the experience yougain with each sampling event.

How to fill sample bottlesThis section and an illustrated appen-dix at the end of this guide describehow to collect a sample properly. Col-lecting a grab sample can be as simpleas holding a bottle under the storm-water falling from a pipe and fillingthe bottle properly. Still, the persondoing the sampling must use care inapplying the principles outlined be-low so that the sample will be repre-sentative of the water being sampled.Additional information regardinggrab sampling is available in Ecol-ogy’s standard operating procedures(SOPs) for grab sampling online athttp://www.ecy.wa.gov/programs/eap/qa/Agency/ECY_SOP_GrabSampling_v1_0.pdf.

Simple principles ofgood grab sample collection:

�Wear disposable powder-freegloves when sampling.

�Grab samples with the stormwaterentering directly into bottlessupplied by your lab rather than bytransferring the samples from acontainer that may not be clean. Metalcontamination of ordinary containersis common and household detergentsoften contain phosphorus, a testedparameter for some industries. Again,transferring the sample from anothercontainer is not an option for TPHsamples under any circumstances.

�When holding the sample bottleyour lab has provided, keep yourhands away from the opening inorder to prevent contaminating thesample.

�Always hold the bottle with itsopening facing upstream (into theflow of water) so that the water entersdirectly into the bottle and does notfirst flow over the bottle or yourhands.

�Sample where the water has amoderate flow and, if possible, someturbulence, so that the stormwaterdischarge will be well-mixed and thesample will be representative.Sampling in still water should beavoided. Include in your field book anote about the sample location andhow briskly the water appears to bemoving.

�Sample from a central portion ofthe stormwater flow, avoidingtouching the bottom of channels orpipes so as not to stir up solidparticles.

�Do not rinse or overfill the bottles.The bottles supplied by your lab forsome parameters (ammonia andphosphorus) will include small

Page 11 Conducting Sampling at Your Facility

Have your sampling

kit ready to go.

amounts of liquid preservative(generally a few drops). Fill the bottle toabout ½ inch of the top (not quite full)to ensure that no preservative is lost.

�As soon as the sample is collected,cap the bottle and label it. It isimportant that the bottles are labeledcorrectly so that the lab will be able toidentify samples by sample site andensure proper preservation for eachparameter. It is a good idea to placesample bottles in reclosable bags. Placethe samples in a picnic cooler partiallyfilled with ice. Plan to maintain ice inthe picnic cooler until the samplesarrive at the lab. Remember to makecertain that the samples will bedelivered to the lab soon enough for thelab to meet holding times.

TPH sampling raisesadditional concerns:

�Oil and grease floats on water soTPH sampling requires specialattention. TPH samples must becollected directly into the samplebottles supplied by the lab because oiland grease tends to stick to the sidesof containers. Do not rinse thesampling bottles beforehand or pourthe sample from another container.Do not fill the bottle completely anddo not pour out some of the sample ifthe bottle is overfilled by mistake. Ifyou do overfill a bottle, use a newbottle instead to collect your sample.Because you only get one try at fillinga TPH bottle, it is a good idea to haveplenty of extra bottles on hand.

�TPH samples should be collectedas the stormwater falls from a pipe orfrom a running, turbulent stream offlow when possible so the source willbe well mixed. When the samplesmust be collected from a watersurface, the person holding the bottleshould plunge it below the surface ina sweeping arc and then bring itupwards through the water surfaceagain, so the water surface is brokentwice by the mouth of the bottle. Be

sure to note in your field book howyou collected your samples as this isespecially important for the TPHsample.

Keeping recordsSection S9 on page 37 of the generalpermit specifies requirements for re-porting and recordkeeping. In orderto comply with the requirement thatlab reports include sampling date andsampling location, you will need tosupply this information to the labwhen submitting samples. You cando this by using the sample locationas the field station identification onyour labels or sample tags.

You should purchase a notebookfor use in the field. Water resistant“rite in the rain” notebooks serve thepurpose well.

Section S4.B3.on page 22 of thepermit requires that you record thedate, exact place, method, time ofsampling or measurement, and thename of the individual who per-formed the sampling or measurement(the section also specifies some re-quirements for lab recordkeeping).Record following information foreach stormwater sample taken andmake it available for Ecology review:

a) Sample date.

b) Sample time.

c) A notation describing if thePermittee collected the sample withinthe first 12 hours of stormwater dis-charge events.

d) An explanation of why the Permitteecould not collect a sample within thefirst 12 hours of a stormwater dischargeevent, if it was not possible.

e) Sample location (using SWPPPidentifying number).

f) Method of sampling, and methodof sample preservation, if applicable.

g) Name of the individual whoperformed the sampling.

Conducting Sampling at Your Facility Page 12

Take notes! Writing

down your

observations at the

time of sampling is

important.

Although not required, it would alsobe beneficial to record the followinginformation:

�Weather preceding the sampling event:- how many days/weeks/monthssince last significant rainfall.

- estimate of time it began raining.- estimate of time that dischargebegan at the sampling point.

- amount (inches) and/or intensityof precipitation.

- whether discharge includes iceor snowmelt runoff.

�How you collected the sample,example, “from a ditch by hand” or“from a manhole with the bottles on apole”.

�The number and types(parameters) of samples collected.

�Field measurement results, such aspH or visible oil sheen.

�Any unusual circumstances thatmay affect the sample results.

Entries in the field book should bemade with ink. If you make an errorin the field book, cross it out ratherthan whiting out or erasing. Numberthe pages of the field book consecu-tively. To ensure that the bound fieldbook is a complete record, do not rippages from it.

When the sampled stormdoesn’t meet the requiredcriteriaThere may be times when, despiteyour best efforts, you are unable tocollect grab samples during the first12 hours of a storm event. When thishappens, the general permit statesthat the permittee must still collectand submit a stormwater samplingresult, and must include an explana-tion with the sampling records (e.g.,record in field notebook).

Page 13 Conducting Sampling at Your Facility

Get the best sample

you can.

Special Sampling Considerations

Safety should be the primary con-sideration in sampling. Samples

should never be collected in a waythat compromises the safety of thesampler. In cases where there is aphysical hazard, such as a trip hazardor when sampling near deep waterbodies, samplers should work inpairs. Do not wade in water wherethe estimated depth in feet times thevelocity in feet per second is equal toor greater than 8, as swift currents canlead to drowning accidents. Be awareof the slip hazard common near thebanks of water bodies and decidewhether a bank is too steep to negoti-ate safely. Safety comes down to indi-vidual judgment. Never put yourselfin a position you consider to be un-safe. Collecting grab samples ofstormwater is basically a simple pro-cess but an important one since get-ting good results depends on propersampling. Samples can be collectedeasily in some locations, but not allstormwater discharges are as readilysampled as the flow in a ditch or froma pipe falling into a receiving water.Below are some situations you mayencounter and suggested approachesfor handling them. Because TPH sam-ples must be collected directly intothe bottle supplied by the lab we willconsider only methods for collectingsamples directly by hand or with abottle attached to a pole. When sam-pling in these or other situations,keep in mind the steps outlined in thesection, How to Fill Sample Bottles. Ad-ditional information is available inEcology’s standard operating proce-dures (SOPs) for stormwater sam-pling available online athttp://www.ecy.wa.gov/programs/eap/quality.html.

Sampling as stormwaterdischarges from a pipeinto a receiving waterIf stormwater is being discharged fromyour facility through a pipe into aditch, creek, or other receiving water,it can be readily sampled as it fallsfrom the pipe before it reaches the re-ceiving water if the discharge pipe issafely accessible and not submerged.Hold the bottles with the bottle open-ing facing upstream into the flow andbe sure not to overfill them. You mayneed to fasten the collection bottles toa pole to reach the pipe. Attaching abottle to a pole is described in the sec-tion below, Sampling from a Manhole.

Sampling from a manholeWhen sampling from the manhole ofa municipal storm sewer, rememberto contact the municipality before-hand. Be sure to discuss safety con-cerns when talking to themunicipality about sampling. Open amanhole with a hook or pick axe, ex-ercising care not to drop the manholecover on hands or feet. You shouldnot, under any circumstances, enterthe manhole unless trained to safelyenter confined spaces, but you cansample the flow in a manhole fromabove ground by taping the samplingbottles, one at a time, to a pole andlowering the pole into the manhole.

Each bottle can be fastened to thepole by holding the bottle against itand wrapping tape tightly around thebottom and the top of the bottle as youhold the bottle firmly to the pole. Fila-ment strapping tape works well forthis purpose as it is waterproof andstrong. If the flow in the storm sewer isshallow, the bottle may have to be po-sitioned horizontally with the bottle’sopening somewhat higher than its bot-tom. When sampling in a manhole, be

Special Sampling Considerations Page 14

Don’t take risks.

Know how to

sample safely.

careful not to scrape the bottle againstthe sides of the pipe to avoid pickingup extras solids in your sample.

Collecting into bottles for TPH sam-ples with a pole is done by plungingthe bottle on the pole below the watersurface and back upwards. This mustbe done as a single motion and onlyonce. Because you only get one try atgetting a good TPH grab sample, it maytake some practice and extra bottles tocollect the amount of sample you needwithout overfilling the bottle.

Collecting samples, other thanTPH, into bottles with preservative canbe done by quickly plunging the poleinto the flow repeating if necessary un-til the bottle is most but not all of theway full. If you overfill the bottle, re-move it, tape a clean bottle to the pole,and try again. Be sure, when collectingsamples with a pole, to follow cleanprinciples by keeping the pole down-stream of the bottle while sampling.

Sampling from a drainageditch or swaleIf a drainage ditch carries stormwaterflow from your facility offsite, and ifit carries no flow other than the flowfrom your facility, you can sample thewater in the ditch simply by placingthe bottle where the flow is free, withthe bottle opening facing upstream. Ifyou cannot reach a freely flowingportion of the ditch by hand, you mayneed to attach the bottles, one at atime, to a pole for sampling. Followthe procedure outlined in the section,How to Fill Sample Bottles.

If the flow is carried in a smallditch or swale, you can install a bar-rier device in the channel or deepen asmall area so you can gain enoughdepth of flow to sample directly intothe bottles. Make sure to allow forsufficient time after disturbing thebottom so that the solids resultingfrom muddying the water will not be-come part of your sample.

Sampling sheet flowIt is not always possible to samplestormwater runoff in locations suchas ditches or pipes where the flow isconcentrated. Sometimes thepermittee has no choice but to selectsample locations for which sheet flowis sampled before it becomes concen-trated. Approaches to sampling sheetflow are described below and illus-trated in the figures that follow.

In some cases, a stormwater dis-charge from a facility is not concen-trated at any point and leaves theproperty in the form of sheet flow asit runs off a work area or driveway orgrassy area. In this case the flow maybe too shallow for the collection bottleto be filled with sample. It is oftenpossible to find a way to collect thestormwater runoff in these situations.

One way to concentrate sheet flowis to install a barrier device or trough,gutter, or ditch to intercept and con-centrate stormwater flow. As withother sample sites, the flow should bemoving and somewhat turbulent sothe samples will be well-mixed. Besure that any excavation you do doesnot expose the stormwater to be sam-pled to newly worked soil surfacesthat the runoff may erode, increasingthe solids in your samples. You maywant to consider lining the trough,gutter, or ditch with plastic. Be surenot to introduce materials such asmetals that include zinc that may con-taminate the samples. Sheet flow onpaved areas can be concentrated andcollected by constructing smallbumps, similar to speed bumps.

Another way to collect samplesfrom sheet flow is to use a specialperistaltic hand pump to pump sam-ples from shallow surface flows. Thismethod is of limited use for collectingthe samples required by the generalpermit as it cannot be used to collectTPH samples.

Page 15 Special Sampling Considerations

When sampling from a man-

hole, use a pole to safely

sample from above ground.

Avoid touching the sides of

the manhole or pipes with

the bottle to prevent con-

tamination. Place the open-

ing of the bottle upstream so

that the flow enters the bot-

tle directly.

Roger Bannerman of the Wiscon-sin Department of Natural Resourceshas developed simple devices to grabsamples of sheet flow from paved ar-eas, rooftops, and lawns. Though thedevices are intended to be used forsimple, automatic sampling, pouringa container of collected sample intoother sample bottles, the ways inwhich they intercept and concentrateflows can be adopted for direct grabsampling.

The following figures illustrate themethods of sampling sheet flow dis-cussed above:

Sampling from a stormwaterdetention pond or other BMPWhen stormwater from a facility dis-charges after flowing through a de-tention pond or other treatmentsystem, sample as the stormwaterflows out at the discharge point.Ponds may hold stormwater for atime before discharge begins. Samplewithin the first 12 hours from whenthe pond begins to discharge.

Special Sampling Considerations Page 16

Overland flow from vegetated areas can be

sampled by constructing a shallow ditch to

intercept the runoff and a deepened area to

place bottles to catch the runoff.

Deepening an existing ditch can allow sam-

ples to be collected directly into bottles in

some cases. Be careful not to stir up solids

from the sides or bottom of the ditch.

Runoff entering a catch basin can sometimes

be collected directly into bottles by remov-

ing the grate and allowing the runoff to fall

into the bottles.

Overland flow on paved areas can be sam-

pled by constructing asphalt or concrete

bumps to collect and concentrate the flow. A

box positioned below ground surface in the

paved area or the edge of an unpaved area

can provide a place to collect samples di-

rectly into bottles. Please note that dirt and

other debris can often build up along the

bumps and in the “v” so, you may want to

clean the area prior to taking the sample.

Ecology Wants to Hear from You

If you have suggestions on howEcology can improve this guidance

document, have developed innova-tive sampling techniques, or just wantto comment on stormwater sampling,please contact the appropriate permitadministrator for your county:

�City of Seattle, Kitsap, Pierce, orThurston CountyJosh Klimek360-407-7451jokl461@ecy.wa.gov

� Island, King, or San Juan CountyClay Keown360-407-6048ckeo461@ecy.wa.gov

�Adams, Asotin, Columbia, Ferry,Franklin, Garfield, Grant, Lincoln,Pend Oreille, Skagit, Snohomish,Spokane, Stevens, Walla Walla,Whatcom, or Whitman CountyShawn Hopkins360-407-6437shop461@ecy.wa.gov

�Benton, Chelan, Clallam, Clark,Cowlitz, Douglas, Grays Harbor,Jefferson, Kittitas, Klickitat, Lewis,Mason, Okanogan, Pacific, Skamania,Wahkiakum, or Yakima CountyJoyce Smith360-407-6858josm461@ecy.wa.gov

Page 17 Ecology Wants to Hear from You

Appendix - Proper and ImproperMethods of Sampling

DO always wear gloves when taking samples.

DO NOT touch openings of bottles. Keep bot-

tles clean to prevent contamination.

DO NOT sample in stagnant areas with little

flow. DO NOT stir up bottom sediments or

allow foreign materials to enter the sample

bottle. (DO be careful to grab a clean sample

in cases where stormwater runoff is shal-

low.) If the runoff is so shallow that it is not

possible to sample without the sample being

contaminated in the process, then find an al-

ternative way to sample.

DO NOT allow bottle lids to touch ground.

Keep lids clean to prevent contamination.

DO attach a bottle to a pole for sampling in

manholes or when a hand sample would be in

stagnant water. A boathook is used in this

example and the bottle is attached to it with

filament strapping tape.

If the water is too shallow to sample with

the bottle upright on the pole, try taping it

on sideways, but tilted up slightly.

Appendix - Proper and Improper Methods of Sampling Page 18

DO NOT sample with the bottle opening fac-

ing downstream, when using a pole or sam-

pling by hand. Water flowing past your

container, pole, or hand and into the con-

tainer can be contaminated by such contact.

DO sample with the opening of the bottle

facing upstream, into the flow so the water

will enter directly into the bottle. This is

true when sampling either by hand or with a

pole. DO sample water that is rapidly flow-

ing rather than stagnant.

DO NOT allow water to overfill the bottle,

particularly not for sample bottles with pre-

servative. TPH samples should be collected

from water falling into the bottle when pos-

sible, or otherwise in a single swoop.

DO collect samples without overfilling the

bottles.

Page 19 Appendix - Proper and Improper Methods of Sampling

References

Bannerman, R.T.; Owens, D.W.;Dodds, R.B.; Hornewer, N.J., 1993.Sources of Pollutants in WisconsinStormwater, Wat. Sci. Tech. Vol. 28.No. 3-5, pp 241-259.

Colorado Department of PublicHealth and Environment; WaterQuality Control Division; ColoradoDischarge Permit System, 1996.CDPS Stormwater SamplingGuidance Document.

Dodson, Roy D., 1995. Storm WaterPollution Control: Municipal, Industrial,and Construction NPDES Compliance,1999, 1995. Second Edition.McGraw-Hill.

Ecology, 2005. The Industrial Storm-water General Permit: A National Pollut-ant Discharge Elimination System andState Waste Discharge General Permitfor Stormwater Discharges Associatedwith Industrial Activities. State ofWashington Department of Ecology,January 14, 2005.

Ecology, 2000, 1999. Field Operationsand Safety Manual: EnvironmentalAssessment Program, Washington StateDepartment of Ecology, Environmen-tal Assessment Program, UpdatedAugust 2000.

New Jersey Department of Environ-mental Protection Division of WaterQuality, 1998. General Sampling andReporting Guidance for PAS andADI Form.

Thrush, Cindy and De Leon, Dana B.,1993. Automatic Stormwater SamplingMade Easy, Water EnvironmentFederation.

United States EnvironmentalProtection Agency, 1992. NPDESStorm Water Sampling Guidance.EPA 833-B-92-001.

Waschbusch, R.J.; Selbig, W.R.;Bannerman, R.T., 2000. Sources ofPhosphorus in Stormwater and StreetDirt from Two Urban Residential Basinsin Madison, Wisconsin, 1994-95.National Conference on Tools forUrban Water Resource Managementand Protection Proceedings, February7-10, 2000, Chicago, IL.

Wisconsin Department of NaturalResources Bureau of WaterManagement Municipal WastewaterSection – Storm Water Unit, 1994.Wisconsin’s Guidance for IndustrialStorm Water Monitoring.

Torno, Harry C., 1995. StormwaterNPDES Related Monitoring Needs,American Society of Civil Engineers.