post-construction storm water control for new developments and redevelopment projects presenters:...

Post-Construction Storm Water Post-Construction Storm Water Control for New Developments Control for New Developments and Redevelopment Projectsand Redevelopment Projects

Presenters:Presenters:Christe Alwin, Lansing District OfficeChriste Alwin, Lansing District OfficeRalph Reznick, Nonpoint Source UnitRalph Reznick, Nonpoint Source Unit

MS4 Permit ReferencesMS4 Permit References

Watershed Permit MIG610000Watershed Permit MIG610000Part 1.A.4.b.4. (Pages 15-17)Part 1.A.4.b.4. (Pages 15-17)

Jurisdictional Permit MIS049000Jurisdictional Permit MIS049000Part 1.A.8. (Pages 10-12)Part 1.A.8. (Pages 10-12)

City of Battle Creek—porous pavement

Core RequirementCore Requirement Develop, implement, and enforce a Develop, implement, and enforce a

program through an ordinance or other program through an ordinance or other regulatory mechanism to address post-regulatory mechanism to address post-construction storm water runoff from:construction storm water runoff from: all new and redevelopment projects that all new and redevelopment projects that

disturb disturb ≥≥1 acre, and1 acre, and projects that disturb <1 acre if they are part of projects that disturb <1 acre if they are part of

a larger common plan of development or sale a larger common plan of development or sale that would disturb that would disturb ≥≥1 acre.1 acre.

Applies to Permittee and Non-Permittee Projects

What is Post-Construction Storm What is Post-Construction Storm Water Runoff?Water Runoff?

City of Battle Creek—green roof

The storm water that would flow from a project site to an MS4 or surface waters of the state following construction.

Scope of Post-Construction Control Scope of Post-Construction Control RequirementsRequirements

Watershed Permit:Watershed Permit: Across the permittee’s jurisdiction in the Across the permittee’s jurisdiction in the

regulated area (the Urbanized Area and regulated area (the Urbanized Area and watershed area).watershed area).

Jurisdictional Permit:Jurisdictional Permit: Discharges to the permittee owned or Discharges to the permittee owned or

operated MS4 within the Urbanized Area.operated MS4 within the Urbanized Area.

Example 1 - Permittee with Watershed Permit

MS4 A

MS4 B

MS4 D

MS4 C

Deferred Watershed

Watershed Not Deferred

Urbanized Area

Scope of Post-Construction Control Scope of Post-Construction Control RequirementsRequirements

Watershed Permit:Watershed Permit: Across the permittee’s jurisdiction in the Across the permittee’s jurisdiction in the

regulated area (the Urbanized Area and regulated area (the Urbanized Area and watershed area).watershed area).

Jurisdictional Permit:Jurisdictional Permit: Discharges to the permittee-owned or Discharges to the permittee-owned or

operated MS4 with the Urbanized Area.operated MS4 with the Urbanized Area.

Example 2 – Permittee with Jurisdictional Permit

MS4 A MS4 CUrbanized Area

MS4 B

Non-Urbanized Area

MS4 D MS4 E

Decision Flow ChartDecision Flow Chart

How is the post-construction program How is the post-construction program implemented and enforced?implemented and enforced?

OrdinanceOrdinanceOther regulatory mechanismOther regulatory mechanismA combination of bothA combination of both

Likely Scenarios for Applicability of Ordinance Likely Scenarios for Applicability of Ordinance and Other Regulatory Mechanismsand Other Regulatory Mechanisms

Permittee Type

Ordinance

Other Regulatory Mechanism

Local Permit Program

Internal Written Policy

City ♦ ♦

Village ♦ ♦

Township (Watershed General Permit) ♦ ♦

Township (Jurisdictional General Permit) w/private discharges to its MS4

♦ ♦

Township (Jurisdictional General Permit) w/out private discharges to its MS4

♦

County Road Commission Both

County Drain Commissioner Both

County Administration Both

Public Institution ♦

Permittee ExpectationsPermittee Expectations

Establish a post-construction control program through Establish a post-construction control program through an ordinance or other regulatory mechanism.an ordinance or other regulatory mechanism.

May rely on others to assist with completing the May rely on others to assist with completing the necessary reviews and calculations.necessary reviews and calculations.

Compliance with permit requirements is Compliance with permit requirements is ultimately the responsibility of the ultimately the responsibility of the

permittee.permittee.

Post-Construction Storm Water Runoff Post-Construction Storm Water Runoff Control Program Required ComponentsControl Program Required Components

Minimum Water Quality Treatment Volume Minimum Water Quality Treatment Volume StandardStandard

Channel Protection CriteriaChannel Protection Criteria Site Plan RequirementsSite Plan Requirements Operation and Maintenance RequirementsOperation and Maintenance Requirements Enforcement MechanismsEnforcement Mechanisms Recordkeeping ProceduresRecordkeeping Procedures

City of Lansing—raingardens

Program Components

Minimum Water Quality Treatment Volume StandardChannel Protection CriteriaSite Plan RequirementsOperation and Maintenance RequirementsEnforcement MechanismsRecordkeeping Procedures

Minimum Treatment Volumes:Minimum Treatment Volumes:

1 inch of runoff generated from the entire site (½ inch 1 inch of runoff generated from the entire site (½ inch optional for the Watershed Permit if the Watershed optional for the Watershed Permit if the Watershed Management Plan supports it)Management Plan supports it)

The calculated site runoff from the 90 percent annual The calculated site runoff from the 90 percent annual non-exceedance storm for the region or localitynon-exceedance storm for the region or locality

Location and Section CodeLocation and Section Code

KentonKenton11

NewberryNewberry22

KalkaskaKalkaska33

MioMio44

BaldwinBaldwin55

AlmaAlma66

SaginawSaginaw77

Gull Gull LakeLake

88

LansingLansing99

Detroit Detroit MetroMetro

1010

10 percent 10 percent exceedance exceedance stormstorm

0.90"0.90" 0.80"0.80" 0.75"0.75" 0.76"0.76" 0.87"0.87" 0.92"0.92" 0.90"0.90" 0.95"0.95" 0.87"0.87" 0.89"0.89"

period of period of record record evaluatedevaluated

5/48-5/48-12/9912/99

1/48-12/991/48-12/99 5/48-12/995/48-12/99 5/48-5/48-12/9912/99

6/48-6/48-12/9912/99

5/48-5/48-12/9912/99

1/48-12/991/48-12/99 5/48-5/48-12/9912/99

5/48-5/48-12/9912/99

12/58-12/58-12/9912/99

number of number of stormsstorms

32333233 38683868 40474047 34803480 39293929 34373437 35393539 40094009 32393239 29442944

minimumminimum 0.10"0.10" 0.10"0.10" 0.10"0.10" 0.10"0.10" 0.10"0.10" 0.10"0.10" 0.10"0.10" 0.10"0.10" 0.10"0.10" 0.10"0.10"

medianmedian 0.28"0.28" 0.25"0.25" 0.25"0.25" 0.25"0.25" 0.27"0.27" 0.29"0.29" 0.29"0.29" 0.29"0.29" 0.27"0.27" 0.29"0.29"

meanmean 0.42"0.42" 0.38"0.38" 0.37"0.37" 0.36"0.36" 0.41"0.41" 0.43"0.43" 0.42"0.42" 0.43"0.43" 0.41"0.41" 0.42"0.42"

maximummaximum 5.45"5.45" 4.18"4.18" 3.26"3.26" 3.13"3.13" 4.21"4.21" 9.33"9.33" 5.51"5.51" 3.95"3.95" 4.95"4.95" 4.34"4.34"

10% Exceedance Storms for Michigan10% Exceedance Storms for Michigan

Simple Method to Calculate Simple Method to Calculate Runoff VolumeRunoff Volume

WQv = Water Quality VolumeWQv = Water Quality Volume = [(P)(Rv)(A)] /12 = [(P)(Rv)(A)] /12

Rv = 0.05+0.009(I)Rv = 0.05+0.009(I)I = Impervious Cover (Percent)I = Impervious Cover (Percent)Minimum Rv = 0.2Minimum Rv = 0.2P = 90% Rainfall Event Number P = 90% Rainfall Event Number A = site area in acresA = site area in acres

www.semcog.org/LowImpactDevelopment.aspx

Minimum Treatment Volume

TSS

Land Use Category Percent Imperviousness Mean (mg/l) Min (mg/l) Max (mg/l)

Forest/Rural Open 2 51 -- --

Urban Open 11 51 -- --

Agricultural /Pasture 2 145 -- --

Low Density Residential 19 70 2 367

Medium Density Residential 38 70 2 367

High Density Residential 51 97 2 380

Commercial 56 77 5 280

Industrial 76 149 5 271

Highways 53 141 130 406

Taken from "Rouge River Wet Weather Demonstration Project, Selection of Stormwater Pollutant Loading Factors", RPO-MOD-TM34.00, October 1994, Table 3-13

Treatment methods shall be designed on a site-specific basis to achieve the following:

• Minimum of 80 percent removal of total suspended solids (TSS), as compared with uncontrolled runoff, or• Discharge concentrations of TSS not to exceed 80 milligrams per liter (mg/l)

Treatment DesignTreatment Design

Treatment MechanismsTreatment Mechanisms

• Settling• Filtering• Absorption• Chemical Treatment• Mechanical Treatment


TSS TP Sol P TN NOx Cu Zn

Stormwater Dry Ponds

Quantity Control Pond* 3 19 0 5 9 10 5

Dry Extended Detention Pond 61 20 -11 31 * -2* 29* 29*

Group Median ± 1 Std. Dev 47 ±32 19 ±13 -6 ± 8.7 25 ±16 3.5 ±23 26* 26 ±37

Stormwater Wet Ponds

Wet Extended Detention Pond 80 55 67 35 63 44 69

Multiple Pond System* 91 76 69 N/A 87 N/A N/A

Wet Pond 79 49 62 32 36 58 65

Group Median ± 1 Std. Dev 80 ±27 51 ±21 66 ±27 33 ±20 43 ±39 57 ±22 66 ±22

Stormwater Wetlands

Shallow Marsh 83 43 29 26 73 33 42

Extended Detention Wetland* 69 39 32 56 35 N/A -74

Pond/Wetland System 71 56 43 19 40 58* 56

Submerged Gravel Wetland* 83 64 -10 19 81 21 55

Group Median ± 1 Std. Dev 76 ±43 49 ±36 36 ±45 30 ±34 67 ±54 40 ±45 44 ±40

*Data based on fewer than five data points

NOTES:

N/A indicates that the data is not available.

TSS = Total Suspended Solids; TP = Total Phosphorus; Sol P = Soluble Phosphorus;

TN = Total Nitrogen; NO = Nitrate and Nitrite Nitrogen; Cu = Copper; Zn = Zinc

National Pollutant Removal Performance Database, 2nd EditionNational Pollutant Removal Performance Database, 2nd EditionTable 3.1 Median Pollutant Removal (%) of Stormwater Ponds and WetlandsTable 3.1 Median Pollutant Removal (%) of Stormwater Ponds and Wetlands

National Pollutant Removal Performance Database, Version 3 at:www.cwp.org/Resource_Library/Center_Docs/SW/bmpwriteup_092007_v3.pdf

and The International Stormwater BMP Database at:http://www.bmpdatabase.org/Docs/Performance%20Summary%20June%202008.pdf

Low Impact Development Manual for Michigan available at:http://library.semcog.org/InmagicGenie/DocumentFolder/LIDManualWeb.pdf

and the Guidebook of BMPs for Michigan Watersheds available at:http://www.michigan.gov/deq/0,1607,7-135-3313_3682_3714-118554--,00.html


ReferencesReferencesBMP Performance data can be found in;

BMP design information can be found in;

Minimum Treatment VolumeMinimum Treatment Volume


Total Area X 1 inchTotal Area X 1 inchoror

90 percent annual non-exceedance storm and 90 percent annual non-exceedance storm and appropriate runoff model applied to the site.appropriate runoff model applied to the site.

thenthen

Apply BMP or BMPs necessary to achieve 80% Apply BMP or BMPs necessary to achieve 80% reduction of Total Suspended Solidsreduction of Total Suspended Solids

Program Components

Minimum Water Quality Treatment VolumeChannel Protection CriteriaSite Plan RequirementsOperation and Maintenance RequirementsEnforcement MechanismsRecordkeeping Procedures

Channel Protection Criteria:Channel Protection Criteria:

Maintain post-development site runoff volume Maintain post-development site runoff volume and peak flow rate at or below existing levelsand peak flow rate at or below existing levels

All storms up to the 2-year, 24-hour eventAll storms up to the 2-year, 24-hour event

Existing levels = runoff flow volume and rate for the last land use prior to the planned new development or

redevelopment.

Channel Protection Criteria

Stream StabilityStream Stability

The ability of a stream, over time, to maintain its pattern, dimension and profile such that, the channel neither aggrades or degrades and is able to transport without adverse impact the flow and sediment from it’s watershed.


Definition: Bankfull DischargeDefinition: Bankfull DischargeThat discharge which barely That discharge which barely overtops the channel banksovertops the channel banks

Maximum deposition & erosion circulation cell development


The most effectivesediment discharge, over time, occurs at the bankfull flow ratewhich is between the 1 to 2 year recurrence interval.

At the bankfull flow,the stream bottom picksup and moves, then redistributes its selfin the same pool &riffle patterns existingprior to the bankfull discharge.

Taken from Rosgen, 1996Channel Protection Criteria

Streams become unstable due to:Streams become unstable due to:

• Changes in Climate• Changes in Hydrology• Changes in Topography• Changes in Vegetation• Changes in Geology• Alterations of the Stream Channel


The Channel Protection requirements in the MS4 The Channel Protection requirements in the MS4 Permit address changes in hydrology due to Permit address changes in hydrology due to development and the negative channel responses that development and the negative channel responses that result.result.

Maintaining Predevelopment Maintaining Predevelopment HydrologyHydrology

Time of Concentration (Tc)Time of Concentration (Tc) The time it takes water to get from the farthestThe time it takes water to get from the farthest point in point in

a watershed to a point of collection.a watershed to a point of collection. VolumeVolume

The quantity of water that runs off a site during a The quantity of water that runs off a site during a storm event.storm event.

Peak Flow RatePeak Flow Rate The highest flow rate of a storm event.The highest flow rate of a storm event.


CN

CN


Calculates rate and volume of storm runoff using the unithydrograph method for runoff distribution and the curvenumber method of land use runoff response.

www.michigan.gov/deqstormwater (under the “Municipal Program/MS4 Compliance Assistance” link, then the “Guidance for Calculating Runoff Volume and Peak Flow Rate” link)

24 Hour24 HourPrecipitationPrecipitationRainfall Frequency Atlas of Rainfall Frequency Atlas of

the Midwestthe Midwest, Bulletin 71, , Bulletin 71, Midwestern Climate Center, Midwestern Climate Center,

19921992

Hydrograph for a farm on sandy soil or woods on loamy soil.Hydrograph for a farm on sandy soil or woods on loamy soil.

Qp=23 cfs V=5 acre-ft.

Dave Fongers - DNREChannel Protection Criteria

Loss of infiltration due to development increases total runoff Loss of infiltration due to development increases total runoff volume and peak flows. volume and peak flows.







More rapid runoff further increases peak flows. More rapid runoff further increases peak flows.


Controlling Time of ConcentrationControlling Time of Concentration

Maintain Natural Drainage PathsMaintain Natural Drainage Paths Use open swalesUse open swales Increase surface roughnessIncrease surface roughness Detain flowsDetain flows Minimize disturbanceMinimize disturbance Flatten grades in disturbed areasFlatten grades in disturbed areas Disconnect imperviousnessDisconnect imperviousness Connect pervious and vegetated areasConnect pervious and vegetated areas


CN

CN


Runoff Curve Numbers Runoff Curve Numbers For Urban AreasFor Urban Areas


MeadowCN = 71

1 Acre Site on C Soils1 Acre Site on C Soils

Paved Commercial Site100% Impervious

CN = 98

Building

Paved Parking

2 year runoff volume = 1640 ft3 2 year runoff volume = 7950 ft3

Runoff Volume to Remove

6310 ft3

Can be accomplishedwith rain gardens on

approximately 20% of site



2-Year, 24-Hour Rainfall ): 2.42 in

Pre-Development Conditions

Cover Type Soil Area Area S Q Runoff1 Runoff Volume2

Type (sf) (ac) (in) (ft3)

Woods / Meadow A 0 30 23.3 0.2393698 0

Open Space A 0 39 15.6 0.03358739 0

Woods B 0 55 8.2 0.06849468 0

Meadow B 0 58 7.2 0.11496845 0

Open Space B 0 61 6.4 0.17287782 0

Woods C 0 70 4.3 0.41762719 0

Meadow C 43560 1 71 4.1 0.45184657 1640.203047

Open Space C 0 74 3.5 0.56379596 0

Woods D 0 77 3.0 0.6906716 0

Meadow D 0 78 2.8 0.73653831 0

Open Space D 0 80 2.5 0.83402715 0

Impervious N/A 0 98 0.20 2.19122478 0

Other: 0 0

TOTAL: N/A 1.0 N/A N/A N/A 1,640

Post-Development Conditions

Cover Type Soil Area Area S Q Runoff1 Runoff Volume2

Type (sf) (ac) (in) (ft3)

Impervious N/A 43560 1.00 98 0.2 2.19122478 7954.145951

0 0.0 0 0

0 0.0 0 0

0 0.0 0 0

0 0.0 0 0

TOTAL: N/A 1.0 N/A N/A N/A 7,954

Runoff Volume Increase (ft3): 6,314

CN (from TR-55)

CN*

101000

CN SaIP

aIP

)(

2)(

AQ 12/1

Reduce Runoff VolumeReduce Runoff Volume

• Infiltrate• Evaporate• Reuse


Open SpaceCN = 79

1 Acre Site on C Soils1 Acre Site on C Soils

2 year runoff volume = 2847 ft3 2 year runoff volume = 1516 ft3

RunoffVolume Reduction

1331 ft3 Woods CN = 70


Channel ProtectionChannel ProtectionDetermine Existing Runoff Volume Using CN MethodDetermine Existing Runoff Volume Using CN Method

thenthen

Determine Proposed Runoff Volume and Subtract Determine Proposed Runoff Volume and Subtract Existing to determine Runoff Volume IncreaseExisting to determine Runoff Volume Increase

thenthen

Apply BMPs to Remove the Runoff Volume Increase Apply BMPs to Remove the Runoff Volume Increase


Channel ProtectionChannel Protection


• Meeting the Channel Protection Criteria for Meeting the Channel Protection Criteria for Volume Control will also meet the Peak Rate Volume Control will also meet the Peak Rate Control requirement in most cases.Control requirement in most cases.

• For NEW development, meeting the Channel For NEW development, meeting the Channel Protection Criteria for Volume Control will also Protection Criteria for Volume Control will also meet the Minimimum Water Quality Treatment meet the Minimimum Water Quality Treatment Volume criteria in almost all cases. Volume criteria in almost all cases.

Special ConditionsSpecial Conditions

RedevelopmentRedevelopment TransportationTransportation Tight SoilsTight Soils Brown FieldsBrown Fields


Permittees are encouraged to discuss Permittees are encouraged to discuss special conditions with District Staff.special conditions with District Staff.

Program Components


Permittees shall include a Permittees shall include a requirement that the developer requirement that the developer prepare and implement site plans for prepare and implement site plans for each project subject to the post-each project subject to the post-construction control requirements.construction control requirements.

Site PlansSite Plans Allows the permittee to require and evaluate Allows the permittee to require and evaluate

post-construction control details at the planning post-construction control details at the planning stage.stage.

Sets a foundation for ensuring finished project Sets a foundation for ensuring finished project sufficiently meets post-construction control sufficiently meets post-construction control requirements.requirements.

Permittees should have a checklist or criteria for Permittees should have a checklist or criteria for plan reviewers.plan reviewers.

Site PlansSite Plans

City of Battle Creek—rain garden

Program Components


Permittees shall ensure long-term Permittees shall ensure long-term Operation and Maintenance (O&M) plans Operation and Maintenance (O&M) plans for the water quality treatment and channel for the water quality treatment and channel protection controls the permittee requires.protection controls the permittee requires.

O&M RequirementsO&M Requirements

O&M requirements shall beO&M requirements shall beincorporated into the permittee’sincorporated into the permittee’sordinance or regulatoryordinance or regulatorymechanism.mechanism.

Applies to structural and vegetative Best Applies to structural and vegetative Best Management Practices (BMPs), including those Management Practices (BMPs), including those owned or operated by the permittee.owned or operated by the permittee.

Permittees shall review O&M plans and have a Permittees shall review O&M plans and have a tracking mechanism for long-term O&M.tracking mechanism for long-term O&M.

O&M RecommendationsO&M Recommendations

Construction inspections, performance bonds, and Construction inspections, performance bonds, and self-certification processself-certification process

Routine ongoing Routine ongoing inspectionsinspections

Maintenance Maintenance agreementsagreements

Tracking O&MTracking O&M

Program Components


The permittee’s ordinance and or regulatory The permittee’s ordinance and or regulatory mechanism is the foundation for implementing mechanism is the foundation for implementing and enforcing the post-construction control and enforcing the post-construction control program.program.

Enforcement MechanismsEnforcement Mechanisms Ordinance and regulatory mechanism contents Ordinance and regulatory mechanism contents

include all of the post-construction program include all of the post-construction program components:components: Treatment Volume StandardTreatment Volume Standard Channel Protection CriteriaChannel Protection Criteria Developer Site Plan RequirementDeveloper Site Plan Requirement Operation and Maintenance RequirementsOperation and Maintenance Requirements Enforcement Mechanisms for Resolving Enforcement Mechanisms for Resolving

NoncomplianceNoncompliance Any Recordkeeping Requirements Any Recordkeeping Requirements Placed on the Placed on the

DeveloperDeveloper

Enforcement MechanismsEnforcement Mechanisms

Resolving noncompliance measures Resolving noncompliance measures include but are not limited to:include but are not limited to: Right of entry for inspectionsRight of entry for inspections Triggers for issuing notices of violationTriggers for issuing notices of violation Authority to require mandatory abatementAuthority to require mandatory abatement Permittee authorization to conduct BMP Permittee authorization to conduct BMP

maintenance and re-coup costsmaintenance and re-coup costs Ability to issue monetary penaltiesAbility to issue monetary penalties

Recordkeeping procedures shall be in Recordkeeping procedures shall be in place to document enforcement of the place to document enforcement of the post-construction control program through post-construction control program through the ordinance or other regulatory the ordinance or other regulatory mechanism.mechanism.

Program Components


Recordkeeping RequirementsRecordkeeping Requirements

Copies of post-construction storm water Copies of post-construction storm water control ordinances, regulatory mechanisms, control ordinances, regulatory mechanisms, and any supplemental procedures.and any supplemental procedures.

Applicable records for all development and Applicable records for all development and redevelopment projects required to comply redevelopment projects required to comply with the post-construction program.with the post-construction program.

Recordkeeping RequirementsRecordkeeping Requirements

Developer Site PlanDeveloper Site Plan ChecklistsChecklists CorrespondenceCorrespondence Final approved designFinal approved design

O&M Plans or AgreementsO&M Plans or Agreements Inspection and certification recordsInspection and certification records BMP tracking systemBMP tracking system O&M inspectionsO&M inspections

Enforcement ActionsEnforcement Actions ViolationsViolations Permittee actions to address violationsPermittee actions to address violations

QuestionsQuestions

post-construction storm water control for new developments and redevelopment projects presenters:...

Documents

new developments

nonpoint source unit

christe alwin

regulatory mechanism

core requirement