Low Impact Development and Stormwater Management in Pennsylvania Villanova Urban Stormwater Partnership – II 1 Low Impact Development

Low Impact Development and Stormwater Management in Pennsylvania

Villanova Urban Stormwater Partnership – www.villanova.edu/VUSP II II 11

Low Impact Development and Low Impact Development and Stormwater Management in Stormwater Management in

PennsylvaniaPennsylvania

Robert G. Traver, Ph.D., PE Robert G. Traver, Ph.D., PE Department of Civil and Environmental EngineeringDepartment of Civil and Environmental EngineeringDirector, Villanova Urban Stormwater PartnershipDirector, Villanova Urban Stormwater Partnership

II. Stormwater Management in PennsylvaniaII. Stormwater Management in Pennsylvania



OutlineOutline

DefinitionsDefinitions Pa Stormwater Management Pa Stormwater Management

HistoryHistory Why the Change? Why the Change? Current Pa Stormwater Current Pa Stormwater

Requirements. Requirements.



Development and the Hydrologic CycleDevelopment and the Hydrologic Cycle

Thanks to MDE

Original from MDE



Definitions: Objectives of SWMDefinitions: Objectives of SWM Protecting Life & lessening Public Health & Safety RiskProtecting Life & lessening Public Health & Safety Risk Reducing Risk of Monetary Damage to Private / Public Reducing Risk of Monetary Damage to Private / Public

PropertyProperty Minimize disruption of Community AffairsMinimize disruption of Community Affairs Protecting Quality of Surface and GroundwaterProtecting Quality of Surface and Groundwater Enhancement of the Quality of Life in Urban AreasEnhancement of the Quality of Life in Urban Areas

– ASCE Stormwater Manual of PracticeASCE Stormwater Manual of Practice



ASCE Code of EthicsASCE Code of Ethics– Engineers shall hold paramount the safety, Engineers shall hold paramount the safety,

health, and welfare of the public and shall strive health, and welfare of the public and shall strive to comply with the principles of to comply with the principles of sustainable sustainable developmentdevelopment in the performance of their in the performance of their professional duties – (ASCE 2002)professional duties – (ASCE 2002)



Definitions - FloodingDefinitions - Flooding

Natural - every 2 years out of channel….Natural - every 2 years out of channel…. Multiple CausesMultiple Causes

– Rains too hardRains too hard– drainage system inadequatedrainage system inadequate– urbanization increases volume / riskurbanization increases volume / risk

opposite… drought?opposite… drought?



““Risk” - DefinitionRisk” - Definition

Return Period (T)Return Period (T)– Rainfall event equaled or exceeded over a yearRainfall event equaled or exceeded over a year– T = 1/P x 100 2 year storm ~ 50% (P)T = 1/P x 100 2 year storm ~ 50% (P)– 100 ~~~~~~ 1%100 ~~~~~~ 1%

Risk = 1-(1-P)^nRisk = 1-(1-P)^n



Definitions - Floodplain & Stormwater Definitions - Floodplain & Stormwater ManagementManagement

Distinction Between - Large vs. Small Sites?Distinction Between - Large vs. Small Sites?– Both Required by Regulation Both Required by Regulation

Degree? Agency?Degree? Agency?– Floodplain – RiverFloodplain – River– Stormwater - WatershedStormwater - Watershed– Stormwater - Growing Quality OrientationStormwater - Growing Quality Orientation– Flood Plain - Protection –higher priorityFlood Plain - Protection –higher priority

SimilaritiesSimilarities– Life & SafetyLife & Safety– Public Interest Intense - but brief & InfrequentPublic Interest Intense - but brief & Infrequent– Coming together!Coming together!

Similar structural / nonstructural measuresSimilar structural / nonstructural measures Similar Design Tools - same methods, different orientationSimilar Design Tools - same methods, different orientation Same SystemSame System



Pa SWM - Historically Based on……..Pa SWM - Historically Based on……..

Groundwater Rich Concern over Peak Flows / Flooding (property damage)

Channel Stability (Cost) “Drainage” Pics from MDE (except as noted)



1978 – PA ACT 1671978 – PA ACT 167

Peak Flows Limited to Peak Flows Limited to Preconstruction LevelsPreconstruction Levels

All Points Leaving SiteAll Points Leaving Site Municipal ImplementationMunicipal Implementation



1978 - FOCUS1978 - FOCUS

Peak FlowsPeak Flows Large Storms (100 Yr?)Large Storms (100 Yr?) Individual SitesIndividual Sites

– ““downstream property downstream property line”line”

– Detention BasinsDetention Basins



From old Design Manual



0

200

400

600

800

1000

1200

1400

1600

0 120 240 360 480 600 720

Time - Min

CF

S

PreConstruction

PostConstruction

Post W/Detention

Storm HydrographStorm Hydrograph

Pre

Post

Post W/ SWM



1978 - RESULTS1978 - RESULTS Flow Collected and Flow Collected and

ConcentratedConcentrated Detention BasinsDetention Basins

– BIGBIG– Bottom of SiteBottom of Site

Traver 1978



1978 - Results1978 - ResultsPost

PreTime

Flow

Post w/ SWM basin

Lost InfiltrationIncreased Channel Erosion



ASCE Journal of HydraulicsASCE Journal of Hydraulics

Nov 1979 – “Downstream Effects of Stormwater Nov 1979 – “Downstream Effects of Stormwater Management Basins” – Richard McCuenManagement Basins” – Richard McCuen– It is recognized that the urbanization process is responsible for It is recognized that the urbanization process is responsible for

increases in both runoff flow rates and sediment volumes…. The increases in both runoff flow rates and sediment volumes…. The question that has led to much consideration is: Are SWM Basins question that has led to much consideration is: Are SWM Basins effectively meeting the intent of stormwater management?”effectively meeting the intent of stormwater management?”



1983 - ACT 167 REVISED!1983 - ACT 167 REVISED! Enabled Watershed PlanningEnabled Watershed Planning

– plans revised every five yearsplans revised every five years– considers existing trouble areasconsiders existing trouble areas– usually developed by countyusually developed by county

Peak FlowsPeak Flows– limited to preconstruction levelslimited to preconstruction levels– limited by effect on Watershedlimited by effect on Watershed

Municipal Implementation Municipal Implementation



1983 - FOCUS1983 - FOCUS

Peak Flows Peak Flows 2 ~ 100 Year Storms2 ~ 100 Year Storms Watershed Drainage SystemWatershed Drainage System

– Release RateRelease Rate



1983 - RESULTS1983 - RESULTS Flow Collected and ConcentratedFlow Collected and Concentrated Bigger Detention BasinsBigger Detention Basins

– 2 ~ 100 year storms2 ~ 100 year storms– Release Rate ~ Watershed LocationRelease Rate ~ Watershed Location

OwnedOwned– Homeowners AssociationsHomeowners Associations– MunicipalMunicipal



IssuesIssues



Act 167 StatusAct 167 Status Dec 1999 - PaDEP Dec 1999 - PaDEP







EPA Region III WebsiteEPA Region III Website



ASCE Journal of HydraulicsASCE Journal of Hydraulics April 1980 – “Stormwater Detention in Developing April 1980 – “Stormwater Detention in Developing

Watersheds” – C Amandes, P. BedientWatersheds” – C Amandes, P. Bedient– Urban Stormwater runoff has become the major source of stream Urban Stormwater runoff has become the major source of stream

pollution in many urban areas as point source effluents have been pollution in many urban areas as point source effluents have been largely controlled through improved treatment.largely controlled through improved treatment.

July 1988 – “Multicriterion Stormwater Management July 1988 – “Multicriterion Stormwater Management Methods” – R. McCuen & G. MoglenMethods” – R. McCuen & G. Moglen– Both theory and experience indicate that, while detention basins Both theory and experience indicate that, while detention basins

designed to control peak discharge are effective in controlling the designed to control peak discharge are effective in controlling the peak rates, the basins are ineffective in in controlling the peak rates, the basins are ineffective in in controlling the degradatation of erodible channels downstream of the basin.degradatation of erodible channels downstream of the basin.



What do we design for?What do we design for?

0

10

20

30

40

50

0 1 2 3 4 5 6 7

Daily Rainfall (in)

Yea

rly

Vol

(in.

)

0%

6%

12%

18%

24%

30%

Perc

ent p

er In

terv

al

Sum Precip. - in

Interval Precip. - %

1948-2001intervals - .25"



The “old” way- directly connectedThe “old” way- directly connected

Roof

DrivewayStreet

Inlet Culvert

Post

• Infiltration -- Decreased• Baseflow -- Decreased• Groundwater Recharge -- Decreased• Runoff Quality -- Decreased• Stream Bank Erosion -- Increased

•Runoff •Speed -- Increased•Peak Flows -- Increased•Volume -- Increased•No Chance to Infiltrate•No Pollutant Filtration



Pa Comprehensive Stormwater PolicyPa Comprehensive Stormwater Policy Protect and maintain stream uses/water quality;Protect and maintain stream uses/water quality; Protect, maintain and sustain water quantity; and Protect, maintain and sustain water quantity; and Integrate federal stormwater management Integrate federal stormwater management

requirements. “requirements. “NPDES – II”” Best Management Practice (BMP) approach to Best Management Practice (BMP) approach to

stormwater management that emphasizes stormwater management that emphasizes groundwater recharge and the reduction of groundwater recharge and the reduction of impacts from discharges to surface water.impacts from discharges to surface water.

PaDEP Aug 2002



Comprehensive Stormwater Comprehensive Stormwater Management ProgramManagement Program

Pa SW Mgt SymposiumPa SW Mgt Symposium

Villanova UniversityVillanova University

October 16,2003October 16,2003

Durla Lathia, P.E.Durla Lathia, P.E.

Bureau of Watershed ManagementBureau of Watershed Management

Pa DEPPa DEP

The following slides are excerpts from a presentation Durla Lathia

PaDEP Presentation – Pa SWM Symposium Oct 2003



DEP’s Initiative For Public Input DEP’s Initiative For Public Input for for New DirectionsNew Directions

15 Water Forums held in 200115 Water Forums held in 2001 Public Identified Stormwater Public Identified Stormwater

Management as a Consistent Issue, and Management as a Consistent Issue, and Wanted a Comprehensive Wanted a Comprehensive Implementation of Various Water Implementation of Various Water Management ProgramsManagement Programs




“…..to improve and sustain ground and surface water quality and quantity ……

Pennsylvania’s Comprehensive Stormwater Management Policy

GOAL:

September 2002

www.dep.state.pa.usDirect Link to “Stormwater”




Under what authority was the policy issued?Comprehensive SW Policy

Antidegradation Requirements

Section 93.4a

• Existing In-Stream Water Uses and the Level of Water Quality Necessary to Protect the Existing Uses Shall Be Maintained and Protected

•The Water Quality of High Quality & Exceptional Value Waters Shall Be

Maintained & Protected




Implementation GoalsImplementation Goals To successfully implement the To successfully implement the

Comprehensive Stormwater Comprehensive Stormwater Management Policy the goals Management Policy the goals must:must:

Be reasonably attainableBe reasonably attainable Target and prioritize major obstaclesTarget and prioritize major obstacles Be effectively implemented utilizing Be effectively implemented utilizing

existing resourcesexisting resources




Comprehensive Stormwater Comprehensive Stormwater Management ApproachManagement Approach

Integration of Planning, Technical and Integration of Planning, Technical and Regulatory Programs Regulatory Programs

Financial Incentives Financial Incentives Provide Necessary Technical Tools and Provide Necessary Technical Tools and

Support – BMP Tech ManualSupport – BMP Tech Manual




COMPREHENSIVESW

POLICY

Special Protection

Waters

NPDESConstruction

Permits

NPDESPhase II

MS4 Permits

ACT 167PlanningProgram




NPDES Construction PermitsNPDES Construction Permits PPermits require protection of uses ermits require protection of uses

and maintenance of water qualityand maintenance of water quality– E/S Control Plan to minimize pollutants from E/S Control Plan to minimize pollutants from

earth disturbance activities. earth disturbance activities. – PPost ost CConstruction onstruction SSW W MMgt. Plangt. Plan

Permits now emphasize requirement for Permits now emphasize requirement for PCSM PlansPCSM Plans Identification, Assurance for Operation and Identification, Assurance for Operation and

Maintenance of BMPsMaintenance of BMPs

– Preparedness, Prevention, Contingency PlanPreparedness, Prevention, Contingency Plan




PCSM PLANS

Must Accompany Permit Application

Identifiy BMP’s

BMP’s MUST be Designed and Constructed in accordance with:

DEP Approved Act 167 SW Plan with Water Quality Requirements, if a Plan Exist,

Existing MS4 Municipal Ordinance, IF No Act 167 SW Plan,

A 2-Year - 24 Hour Runoff Volume Difference Management(Post - Pre Development Conditions), If neither Act 167 nor MS4 Municipal Ordinance exists.

A Long Term Maintenance of BMP’s is Required




Act 167 Stormwater Planning ProgramAct 167 Stormwater Planning Program

Incorporates hydrologic and hydraulic Incorporates hydrologic and hydraulic Evaluation of a Watershed for Existing and Evaluation of a Watershed for Existing and Future Land Use Scenario Future Land Use Scenario

Requires County and Municipal participation Requires County and Municipal participation Considers Existing Local Regulatory ProgramsConsiders Existing Local Regulatory Programs Recommends Control of Stormwater Runoff Recommends Control of Stormwater Runoff

from Development Activitiesfrom Development Activities A Recommended Model Ordinance A Recommended Model Ordinance




NPDES Phase II MS4 ProgramNPDES Phase II MS4 Program ““MMunicipal unicipal SSeparate eparate SStorm torm SSewer ewer SSystem (MS4)”ystem (MS4)”

20 Urbanized Areas20 Urbanized Areas 929 municipalities, 30 counties, 14 potential municipalities, plus 929 municipalities, 30 counties, 14 potential municipalities, plus

state and federal institutions (PADOT, PTC, prisons, universities) state and federal institutions (PADOT, PTC, prisons, universities)

Permit Requires Implementation of Permit Requires Implementation of 6 Minimum Control Measures6 Minimum Control Measures– Public EducationPublic Education– Public Participation & InvolvementPublic Participation & Involvement– Illicit DischargesIllicit Discharges– ConstructionConstruction– Post-constructionPost-construction– Pollution Prevention/Good HousekeepingPollution Prevention/Good Housekeeping




NPDES II-MS4 PermitNPDES II-MS4 Permit For General Permits, MS4s have Two For General Permits, MS4s have Two

options:options:– Follow DEP “Follow DEP “SW MGT. PROTOCOLSW MGT. PROTOCOL””

““Pre-approved” Tasks Pre-approved” Tasks Relaxed deadlines for Multi-municipal Efforts, Relaxed deadlines for Multi-municipal Efforts,

Working on Watershed Based ApproachWorking on Watershed Based Approach Funding Opportunity, if Funding Opportunity, if Act 167 Planning is Act 167 Planning is

Involved Involved OrOr

– Develop own programDevelop own program Must get DEP approvalMust get DEP approval No fundingNo funding




Expanded Scope of Act 167 ProgramExpanded Scope of Act 167 Program

In addition to the requirements of the Section In addition to the requirements of the Section 5(b) of the Act, 5(b) of the Act, ALLALL Minimum Control Minimum Control Measures of the NPDES MS4 Permit Measures of the NPDES MS4 Permit requirements may be included in a SW Plan, if requirements may be included in a SW Plan, if Counties and Municipalities wish to do soCounties and Municipalities wish to do so

FundingFunding is also included for the expanded is also included for the expanded scope scope




Act 167 SW Management

Planning

Rate & Volume Control

Water Quality

NPDESMS4

Permit

Special Protection

Waters

InfiltrationGroundwater

Recharge

Tailored Municipal

Ordinances

NPDESConstruction

Permit

Financial Assistance

Technical Assistance




How Does Act 167 SW Planning How Does Act 167 SW Planning Implement Comp SW Policy???Implement Comp SW Policy???

Recommend Measures and Techniques to Recommend Measures and Techniques to Address Stormwater Runoff Impact with a Address Stormwater Runoff Impact with a Goal to Mimic Pre-Development Goal to Mimic Pre-Development Conditions after Development is Conditions after Development is Completed.Completed.

Control Standards for Quantity, Control Standards for Quantity, Quality,Groundwater Recharge and Quality,Groundwater Recharge and Stream ProtectionStream Protection

NPDES Regulatory Components IncludedNPDES Regulatory Components Included




Act 167 SW Planning StatusAct 167 SW Planning Status

85 Plans approved for 47 counties85 Plans approved for 47 counties Plans approved after Aug. 2001 contain WQ Plans approved after Aug. 2001 contain WQ

ComponentsComponents 777 Municipalities to enact and implement 777 Municipalities to enact and implement

ordinancesordinances 42 additional Plans currently under way (42 additional Plans currently under way (23 23

Counties, 603 Municipalities): All Plans have WQ ComponentsCounties, 603 Municipalities): All Plans have WQ Components




STORMWATER ORDINANCESTORMWATER ORDINANCE

MS4 Ordinance(MS4 Ordinance(available on DEP Websiteavailable on DEP Website) )

A General SW Ordinance which includes A General SW Ordinance which includes all the components of Stormwater all the components of Stormwater Management. Counties include this Management. Counties include this ordinance in their SW Plans, subject to ordinance in their SW Plans, subject to watershed specific modifications. watershed specific modifications. Municipalities, not part of a SW Plan, are Municipalities, not part of a SW Plan, are encouraged to consider adoption encouraged to consider adoption




Pa BMP Technical ManualPa BMP Technical Manual

Tech Manual to Provide Computational Tech Manual to Provide Computational Procedures and Specifications- Procedures and Specifications- It will NOT Be a It will NOT Be a Regulatory HandbookRegulatory Handbook

18 Month Project18 Month Project Consultant Has Been SelectedConsultant Has Been Selected Oversight Committee Members AppointedOversight Committee Members Appointed First Oversight Committee Meeting Held on First Oversight Committee Meeting Held on

October 10, 2003October 10, 2003 DEP Contacts: Dennis Stum/Ken ReisingerDEP Contacts: Dennis Stum/Ken Reisinger




Stormwater ManagementStormwater ManagementHow Can We Help How Can We Help ????

Central OfficeCentral Office

Regional OfficesRegional Offices

WWW.DEP.STATE.PA.US

Direct Link to Direct Link to “Stormwater”“Stormwater”


Documents

Low Impact Development and Stormwater Management in Pennsylvania Villanova Urban Stormwater Partnership – II 1 Low Impact Development