Transcription

Guidance for UIC Wells that ManageStormwaterDecember 2006Publication Number 05-10-067

Guidance for UIC Wells that ManageStormwaterPrepared by:Washington State Department of EcologyWater Quality ProgramDecember 2006Publication Number 05-10-067

You can print or download this document from our Web site at:http://www.ecy.wa.gov/biblio/0510067.htmlFor more information contact:Department of EcologyWater Quality ProgramWatershed Management SectionP.O. Box 47600Olympia, WA 98504-7600Telephone: 360-407-6404Headquarters (Lacey) leSan ffersonGraysHarbor ki ldColumbiaYakimaWallaWallaAsotinKlickitatPersons with a hearing loss can call 711 for Washington Relay Service.Persons with a speech disability can call 877-833-6341.If you need this publication in an alternate format, please call the Water Quality Program at360-407-6404. Persons with hearing loss can call 711 for Washington Relay Service. Personswith a speech disability can call 877-833-6341.

Table of ContentsTable of Contents. iAcknowledgements. iiiChapter 1 – Introduction and Background. 11.1 Development of this technical guidance . 21.2 Definition of a UIC well . 2Chapter 2 – How UIC Stormwater Wells are Regulated . 52.1 Using a UIC well for stormwater. 52.2 Prohibitions . 52.3 Rule-authorization or permit. 62.4 Registration . 62.5 Meeting the non-endangerment standard for new wells . 72.5.1 Using the presumptive approach.72.5.2 Using the demonstrative approach.82.6 Existing UIC wells. 82.6.1 Evaluating high threat to ground water for existing wells.92.6.2 Preservation and maintenance projects.92.6.3 Emergency situations .92.7 Requirements for municipalities with national pollutant discharge eliminationsystem (NPDES) permits. 10Chapter 3 – Siting, Design and Construction, Operation and Maintenance . 113.1 Siting . 113.1.1 Minimum siting requirements for rule-authorization under thepresumptive approach .113.1.2 Further siting considerations for UIC wells near drinking water wells .113.1.3 Local siting considerations .113.1.4 Advisory on infiltration and geologic instability .123.1.5 Advisory setbacks for slopes and building foundations .123.2 Design and construction . 133.2.1 Use an approved stormwater manual.133.2.3 Prevent clogging during construction .133.2.3 Stormwater runoff flow control .133.2.4 Depth to bedrock, water table, or impermeable layer.143.2.5 Other advisory design considerations .153.3 Operation and maintenance. 15Chapter 4 - Potential Contaminants in Stormwater Runoff . 17Chapter 5 – Source Control, Pre-Treatment and Vadose Zone Treatment Requirements. 195.1 Source Control . 195.1.1 General guidelines for spills and illegal dumping .205.1.2 Spill containment structures.215.1.3 Spill control devices.21Determination of Treatment and Source Controlfor UIC Wells in Washington StatePage i

5.1.4 Evaluating the need for spill containment structures or control devicesfor other situations .235.2 Pre-treatment. 245.2.1 Preserving infiltration rates.245.2.3 Soluble pollutants.265.2.3.1 Special requirements. 265.2.4 Solids, metals, and oil .275.2.4.1 Tables to determine treatment requirements. 275.2.4.2 Treatment requirements . 285.2.4.3 Oil control . 285.2.4.4 Solids removal . 295.3 Vadose zone treatment capacity. 295.3.1 Classification of vadose zone treatment capacity .305.3.2 Vadose zone materials .325.3.3 Depth to ground water .325.3.4 Exceptions to tables 5.1 through 5.3 based on site-specific or localstudies .335.3.5 Tables to determine pre-treatment requirements for solids, metals, andoils.34Chapter 6 – Bibliography. 39Chapter 7 – Glossary. 41Appendix A – Benchmark Monitoring of Runoff for Nitrate, Nitrite, Ammonia, orPhosphorus for Certain Industrial Activities . 45Appendix B – Report a Spill. 49How To Report a Spill . 49Who to Call . 49Useful Information. 49Page iiDetermination of Treatment and Source Controlfor UIC Wells in Washington State

AcknowledgementsEcology would like to thank the following people who contributed their valuable commitment oftime and energy in helping develop, review, and shape the contents of this document.Nancy Aldrich, City of RichlandMike Barbar, Washington State UniversityTony Barrett, Department of EcologySusan Braley, Department of EcologyGary Beeman, Washington Department of Transportation, South Central RegionBrad Bogus, Kennedy/Jenks ConsultingMichele Brich, Home Builders Association of Tri-CitiesMike Brunfelt, Inter-FluveDoug Busko, David EvansPaula Cox, Chelan CountyKaren Dinicola, Department of EcologyMark Ewbank, Herrera EnvironmentalRick Frye, Department of EcologyDon Gatchalian, Yakima CountyJocelyne Gray, JUB EngineersSteve Hansen, City of SpokaneJim Harakas, Geo EngineersJohn Heinley, Washington Dept. of TransportationMike Hepp, Department of Ecology, Eastern RegionPaul Hill, U Fix It HondaJohn Hohman, City of Spokane ValleyHeather Kibbey, Pierce CountySteve King, City of WenatcheeDave Kliewer, JUB EngineersJohn Knutson, OtakGreg Lahti, Washington Dept. of Transportation, Eastern RegionArthur Lee, Tetra Tech, KCMSandra Levey, Grant CountyKevin Lindsay, Kennedy/Jenks ConsultantsColleen Little, Spokane CountyRyan Lyyski, City of EllensburgGloria Mantz, Spokane CountyKhalid Marcus, Yakima CountyAnn McDonald, URS Corp.Stan MillerBill Moore, Department of EcologyDave Moss, Tetra Tech/KCMLaurie Morgan, Department of EcologyGary Nelson, City of SpokaneHeather Ostenson, RH2 EngineeringDetermination of Treatment and Source Controlfor UIC Wells in Washington StatePage iii

Larry Pearson, County Road Administration BoardBill Peacock, City of SpokaneWayne Peterson, Department of Ecology, Eastern RegionDon Phelps, AAA Auto Wrecking & Sales Inc.Steve Plummer, City of KennewickMitch Reister, Washington Department of TransportationBill Rice, OtakBill Rickard, City of SpokaneTony Righellis, Harper Houf RighellisMel Schaefer, MGS Engineering ConsultantsMary Shaleen Hansen, Department of EcologyBrett Sheffield, City of YakimaBrenda Simms, Spokane CountyGary Smith, Independent Business AssociationJim St. John, David Evans and AssociatesRod Thompson, Department of EcologySteve Worley, City of Spokane ValleyMatt Zarecor, Spokane CountyPage ivDetermination of Treatment and Source Controlfor UIC Wells in Washington State

Chapter 1 – Introduction and BackgroundThis document provides technical guidance for stormwater wells regulated under theUnderground Injection Control (UIC) program. For convenience, we will refer to these as UICwells. UIC wells that are used for stormwater are also commonly referred to as drywells.The purpose of this document is to provide design and pretreatment best management practices(BMPs) for UIC wells used along roads, parking areas and also roof runoff and built on or afterFebruary 3, 2006. These UIC wells are referred to as “new” UIC wells.The UIC rule, Chapter 173-218 WAC, requires a well assessment for UIC wells that wereconstructed prior to February 3, 2006. These UIC wells are referred to as “existing” UIC wells.This document can also be used to complete the well assessment for existing wells.StormwaterStormwater is the water from rainstorms or snow melt that runs over land into ponds, lakes,streams, marine waters, wetlands, drainage ditches, evaporation ponds, and drywells.As stormwater flows, it contacts surfaces that contain pollutants. Roads and parking lots cancontribute oils and metals. Roofs on industrial buildings can collect chemicals that are ventedout of the building and wash off when it rains. Grassy areas like golf courses, cemeteries, andplaying fields may contribute fertilizers and pesticides.The purpose of managing stormwater is two fold: to prevent flooding and to prevent waterpollution. Drainage systems are designed to collect and transport stormwater runoff to preventflooding, and treatment systems are designed to control pollution. Managing stormwater at thesite, such as by using a UIC well, can also contribute to the recharge of ground water resources.For chemicals that are not easy to remove from stormwater, pollution control means going to thesource and preventing it from contacting stormwater in the first place. The methods ofpreventing stormwater pollution are referred to as “best management practices.”UIC ProgramThe Underground Injection Control program was created by Congress to protect undergroundsources of drinking water from discharges of fluids to the ground. The UIC program in the stateof Washington is administered by the Department of Ecology. In 1984, the Department ofEcology adopted Chapter 173-218 WAC - Underground Injection Control to implement theprogram.In Washington all ground water is protected equally under RCW 90.48 and Chapter 173-200WAC Water Quality Standards for Ground Waters of the State of Washington.Determination of Treatment and Source Controlfor UIC Wells in Washington StatePage 1

The two basic requirements of the UIC Program are: Register UIC wells with the Washington State Department of Ecology unless the wells arelocated on tribal land. (Those wells should be registered with the Environmental ProtectionAgency). Make sure that current and future underground sources of ground water are not endangeredby pollutants in the discharge (non-endangerment standard).Since stormwater picks up contaminants as it runs over the land surface, it can pollute groundwater once infiltration occurs.Pollution of ground water from stormwater discharges can be prevented by careful design of theUIC well, strategic siting and effective operation and maintenance. Pollution can also beprevented by use of treatment before discharge to the sub-surface and by reducing thestormwater contact with potential sources of contamination. These methods are covered in thistechnical guidance.1.1 Development of this technical guidanceThe UIC rule was revised in consultation with the UIC Rule Advisory Committee. The UIC rulewas adopted and became effective on February 3, 2006. A subcommittee of the StormwaterManagement Manual for Eastern Washington committee developed the draft version of thisdocument with statewide stakeholder input and public review. This document was originallypublished as interim technical guidance in Ecology Publication Number 04-10-076, theStormwater Management Manual for Eastern Washington.This guidance replaces the section in the Department of Ecology Stormwater ManagementManual for Eastern Washington (SMMEW), Section 5.6 that refers to UIC wells; however, therest of the manual applies.When using this document, please refer also to the Ecology stormwater management manuals foreastern and western Washington or an equivalent department approved manual. An example ofan equivalent manual is the Washington State Department of Transportation Highway ingPublications/Manuals/HighwayRunoffManual.pdf1.2 Definition of a UIC wellA UIC well is a manmade subsurface fluid distribution system designed to discharge fluids intothe ground and consists of an assemblage of perforated pipes, drain tiles, or other similarmechanisms, or a dug hole that is deeper than the largest surface dimension (WAC 173-218030).Subsurface infiltration systems include drywells, pipe or French drains, drain fields, and othersimilar devices that are used to discharge stormwater directly into the ground.Page 2Determination of Treatment and Source Controlfor UIC Wells in Washington State

Drywells are UIC wells completed above the water table so that the bottom and sides aretypically dry except when receiving fluids. Drywells may be stand-alone or as part of a largerdrainage system, such as the overflow for a bio-infiltration swale or other stormwater treatmentBMP.Infiltration trenches with perforated pipe are considered to be UIC wells. This type of infiltrationtrench must be registered with Ecology. However, they must be designed, constructed, operated,and maintained according to an Ecology stormwater manual or another equivalent departmentapproved manual to be rule authorized. This guidance does not apply except for the registrationrequirement.Typical UIC stormwater wells (drywells)The following are not UIC wells; therefore, this guidance does not apply: Buried pipe and/or tile networks that serve to collect water and discharge that water to aconveyance system or to surface water. Surface infiltration basins and flow dispersion stormwater infiltration facilities. Infiltration trenches designed without perforated pipe or a similar mechanism.Determination of Treatment and Source Controlfor UIC Wells in Washington StatePage 3

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Chapter 2 – How UIC Stormwater Wells are Regulated2.1 Using a UIC well for stormwaterThis guidance document applies to UIC wells that receive stormwater from roads, parking areasand also roof runoff.A UIC well may be used to manage stormwater when pollutant concentrations that reach groundwater are not expected to exceed Washington State ground water quality standards (Chapter 173200 WAC). This guidance document describes conditions and requirements that are expected toresult in meeting these standards.UIC wells may be used for overflow from a stormwater facility that is greater than the runofftreatment design storm without further treatment.2.2 ProhibitionsStormwater from the areas listed below may not be discharged to UIC wells because of thepotential to contaminate ground water unless authorized under a permit. Conventionalstormwater treatment is not considered protective of ground water in these situations.Stormwater from these areas must be handled on site with a closed-loop system or discharged tothe sanitary sewer if allowed by the local jurisdiction.The term “area” used here refers to a specific physical portion of an industrial or businessfacility where the activities occur. Stormwater from other portions of the site that do notcontact the areas listed below, such as roofs and parking areas, may be discharged to UICwells. The requirements for roofs and parking areas described elsewhere in this documentmust be met.See 173-218-040(5)(b) for a list of examples of prohibited UIC wells. UIC wells may notreceive stormwater from the following types of areas: Vehicle maintenance, repair and service. Commercial or fleet vehicle washing. Airport de-icing activities. Storage of treated lumber. Storage or handling of hazardous materials. Generation, storage, transfer, treatment or disposal of hazardous wastes. Handling of radioactive materials. Recycling facilities, except for those that recycle only glass, paper, plastic, or cardboard.Determination of Treatment and Source Controlfor UIC Wells in Washington StatePage 5

Industrial or commercial areas that have outdoor processing, handling, or storage of raw solidmaterials or finished products at the facility and are without management plans for properstorage and spill prevention, control, and containment appropriate to the types of materialshandled at the facility (see the Ecology stormwater management manuals for information onstormwater pollution prevention plans and source control). UIC wells may not be used at contaminated sites when the stormwater would increase themobility of the contaminants at the site. For example, a drywell could not be used upgradient of or over the contaminant plume at a leaking underground storage tank site. This isbecause the stormwater could increase the movement of the contaminants.2.3 Rule-authorization or permitUIC wells must either be rule-authorized or covered by a state waste discharge permit to operate.If a UIC well is rule-authorized, a permit is not required. Rule-authorization can be rescinded ifa UIC well no longer meets the non-endangerment standard. Ecology can also require correctiveaction or closure of a UIC well that is not in compliance.A UIC well may be rule-authorized when both of the following requirements are met:1. A registration form must be submitted to the Department of Ecology.2. Discharge from the UIC must not contaminate ground water. This is the “nonendangerment performance standard.”The requirements to meet the non-endangerment standard are detailed in this guidancedocument.2.4 RegistrationResidential UIC wells used for roof runoff or basement flooding control are exempt from theregistration requirement. All other UIC wells must be registered.The registration form can be found at the Ecology Web site dex.html.UIC wells constructed on or after February 3, 2006 are considered to be new. The registrationprovides the department with information needed to determine if the new UIC well meets theconditions to be rule-authorized. The registration form must be submitted prior to construction.The non-endangerment standard must be met (see the next section).UIC wells constructed prior to February 3, 2006, are considered to be “existing.”Page 6Determination of Treatment and Source Controlfor UIC Wells in Washington State

Owners of 50 wells or fewer must register their wells by February 3, 2009, and completetheir well assessment by February 3, 2011. Owners of more than 50 wells must register their wells by February 3, 2011, and completetheir well assessment by February 3, 2013.See section 2.6 and Chapter 173-218-090(2) WAC for more on well assessments.2.5 Meeting the non-endangerment standard for new wellsThe Department of Ecology makes the decision that a UIC well is either rule-authorized or needsa permit based on whether the UIC well meets the non-endangerment standard.There are two ways for a registrant of a new UIC well to show that the well meets the nonendangerment standard and therefore, isn’t required to have an individual permit. One way is to follow the requirements in this technical guidance. The Department ofEcology will presume that the UIC well meets the non-endangerment standard and the wellwill be rule-authorized. This is called the presumptive approach. The other way is for the registrant to demonstrate that the non-endangerment standard hasbeen met in some other way. This is called the demonstrative approach. This is designed toallow alternative methods to demonstrate that the non-endangerment standard has been metand therefore the UIC well may be rule-authorized.2.5.1 Using the presumptive approachTo be eligible for rule-authorization using the presumptive approach, the following must beaddressed according to this guidance or another equivalent department approved localstormwater manual that includes the requirements in this guidance: The potential pollutant loading expected in the stormwater runoff.Source control of pollutants, especially those that are difficult to remove from stormwater byfiltration, settlement, or other treatment technologies.Known treatment methods.The potential treatment capacity of the vadose zone.Siting.Design.Operation and maintenance.The presumptive approach may not be used when BMPs do not exist to remove or reduce acontaminant and/or the vadose zone has no treatment capacity (WAC 173-218-090 (1) (i) (D)).Determination of Treatment and Source Controlfor UIC Wells in Washington StatePage 7

2.5.2 Using the demonstrative approachThe documentation for the demonstrative approach is a site-specific analysis that demonstratesthat the proposed discharge will comply with ground water quality standards.To be eligible for rule-authorization using the demonstrative approach, the following topic areasmust be documented with the UIC well registration. Site-specific analysis of pollutant loading. Site-specific analysis of the treatment capacity of the vadose zone, if used for treatment. How stormwater best management practices (BMPs) were selected. Pollutant removal expected from the selected BMPs. Technical basis supporting the performance claims for the selected BMPs. Assessment of how the selected BMPs will comply with state ground water quality standardsand satisfy state AKART requirements.2.6 Existing UIC wellsUIC wells that were constructed before February 3, 2006, have different requirements than wellsconstructed on or after the revised rule became effective. Existing UIC wells are grandfatheredin with respect to the rules that became effective on February 3, 2006.A well assessment must be completed to determine if any of the existing UIC wells are a highthreat to ground water. UIC wells that are a high threat to ground water must be retrofitted toprotect ground water quality.UIC wells constructed prior to February 3, 2006, must also be registered, if this was notpreviously done.The following is the definition of a well assessment (WAC 173-218-030):Well assessment means an evaluation of the potential risks to ground water from the use of UICwells. A well assessment includes information such as the land use around the well which mayaffect the quality of the discharge and whether the UIC well is located in a ground waterprotection area. It may include the local geology and depth of the ground water in relation to theUIC well if the well is considered a high threat to ground water.This technical guidance may be used as a helpful guide for the well assessment. Here is anexcerpt from WAC 173-218-090(2):“The approach to conducting the well assessment will be determined by the owner. The wellassessment evaluates the potential risks to ground water from the use of UIC wells and includesinformation such as the land use around the well which may affect the quality of the discharge,Page 8Determination of Treatment and Source Controlfor UIC Wells in Washington State

and whether the UIC well is located in a ground water protection area. It may include the localgeology and depth of the ground water in relation to the UIC well if the well is considered a highthreat to ground water. The well assessment requirements will be met if an owner or operatorapplies the storm water best management practices contained in a guidance document approvedby the department to their UIC wells and determines if the UIC well is located in a ground waterprotection area.”2.6.1 Evaluating high threat to ground water for existing wellsIf an existing well was built according to the specifications in this guidance it is not considered ahigh threat to ground water and does not need to be retrofitted, unless site specific informationindicates that a ground water quality problem exists.The following conditions are considered a high threat to ground water for which existing wellsneed retrofitting: UIC wells receiving prohibited discharges (see Section 2.2 Prohibitions). UIC wells receiving a high pollutant load where the vadose zone between the bottom of theUIC well and the top of the ground water has no treatment capacity or the vadose zoneconditions are unknown, according to Tables 5.2-5.4 of this guidance. UIC well structures completed in ground water. If a UIC well has water in it during the dryseason when it has not received any recent discharges, chances are it is sitting in groundwater.2.6.2 Preservation and maintenance projectsA preservation and maintenance project involves removing and replacing a road surface withoutexpanding the impervious surface (Stormwater Management Manual for Eastern Washington,pp. 2-9).The question is whether UIC wells involved in these types of projects are regulated as existing ornew wells.A UIC well that was in use prior to the project is considered an existing well only if it remains inplace. The well may be retrofitted or reconstructed in place without being considered a newwell. Otherwise, it is considered a new well, and the new UIC requirements apply.2.6.3 Emergency situationsIn emergency situations, such as roadway flooding, a jurisdiction may install a UIC well thatdoes not meet the requirements of this guidance on a temporary basis. When weather permits,and within a year of the event, the jurisdiction should ensure that the UIC well meets therequirements of this guidance.For example, excessive winter rainfall overwhelms the capacity of the existing drainage systemalong a road. The water drains onto the road and turns to ice. The jurisdiction installs a newDetermination of Treatment and Source Controlfor UIC Wells in Washington StatePage 9

UIC well to fix the immediate problem and, once the weather permits, implements the requiredbest management practices.2.7 Requirements for municipalities with national pollutant dischargeelimination system (NPDES) permitsMunicipalities that are under an NPDES stormwater permit may also have stormwater dischargesto UIC wells. The Stormwater Management Program required by the NPDES stormwater permitincludes best management practices that also may be applied to stormwater discharges to UICwells. To avoid duplication, municipalities that are under an NPDES stormwater permit maymeet UIC program requirements by applying their Stormwater Management Program to areasserved by UIC wells. See Chapter 173-218-090(1) WAC.Since the NPDES permit does not fulfill all the requirement

wells. UIC wells that are used for stormwater are also commonly referred to as drywells. The purpose of this document is to provide design and pretreatment best management practices (BMPs) for UIC wells used along roads, parking areas and also roof runoff and built on or after February 3, 2006. These UIC