SUNY ESF Workshop

Shohreh Karimipour, P.E.

Enhanced Phosphorus

Removal Standards

Enhanced Phosphorus

Removal Standards

NEW YORK STATE DEPARTMENT OF ENVIRONMENTAL CONSERVATION

PurposePurpose• To develop an effective and

technically defensible criteria to address stormwater design standards in phosphorus-limited watersheds– EOH NYC Water Supplies Watersheds

– Greenwood Lake

– Onondaga Lake

• A supplement to the Existing New York State Stormwater Management Design Manual for enhanced phosphorus control– Provide consistency with NYCDEP watershed rules

– Enhanced Criteria consistent with the current State standards

OverviewOverview• Existing Stormwater Design

Standards– New York State – Watershed Rules

• Enhanced Standards (Supplement)– Defining Enhanced Phosphorus Removal– Overview of Development Process– Recommendations

• Design Standards– Sizing Criteria– Performance Criteria

Marcus Quigley, P.E. Project Manager Eric Strecker, Principal-In-Charge GeoSyntec Consultants

Robert Pitt, Senior Technical Specialist and Technical Review

NYS DEC, Project Management

Technical Advisory Group (TAG)NYCDEPNYSSWCCNYSOAGRiver Keepers (CEA)Insite Engineering

The Project Team

University of Alabama

Design StandardsNYS RequirementsDesign StandardsNYS Requirements

• Sizing Criteria– Capture & treatment 90% Design Storm– Channel protection and flood controls

• Performance Criteria– Removal Efficiency: 80% TSS 40% phosphorus– Standard management practices– Design Specifications

• Can capture and treat the full water quality volume• Provide pretreatment• Have acceptable longevity in the field

Features of Standard SystemsFeatures of Standard Systems

Examples:• Embankment Specifications• Principal/Emergency Spillway

• Inlet Protection• Adequate Outfall Protection

• Sediment Forebay• Media specifications

• Adequate WQv• Multiple Treatment Pathways• Minimum Geometry

• Pond Benches • Pondscaping Plan• Wetland Elements• Pond Buffers / Setbacks

• Non-clogging Orifice• Riser in Embankment• Adjustable Gate Valve• Safety Features

• Maintenance Responsibility• Maintenance Access• Maintenance Schedule

Watershed RulesWatershed Rules

• The Croton Watershed– Sizing Criteria

• Detention of 2-yr., 24-hr. storm• TR-55 calculation method• Pollutant load analysis• 2-yr, 10-yr, 25-yr, 100-yr peak control

– Performance Criteria• infiltration, retention, detention

• Onondaga Lake• Greenwood Lake

Defining EnhancedDefining Enhanced• Performance Criteria

• How much stormwater is prevented? – Hydrologic Source Control– Evapotranspiration– Infiltration

• How much of the remaining stormwater is treated?

– Hydraulic function– Capture and treatment– Bypass

• What is the effluent quality of the treated runoff?

– Effluent quality of the discharge– Seasonal Performance Criteria

Phosphorus and TreatabilityPhosphorus and Treatability• Particulate vs. dissolved forms• Particulate size or settling

velocities• International BMP Database• Research by Pitt, et al. (Wisconsin)• P association with particles < 10 µm

51,90063,10078,8006,6402,16017,2006,400Average

mgP/kgSS

0.45-1 µm

1-2 µm

2-10 µm

10-45 µm

45-106 µm

106-250 µm

>250 µmParticle size

• Sizing analysis as a function of• Treatment volume • Detention time• Permanent pool• Particle settling theory

– Continuous simulation SWMM modeling

• 44 yr hourly data (Carmel)• 120 Model runs

– Event simulation by HydroCAD®• Detention time• Seven scenarios (WQv)

Permanent Pool

Extended Detention outlet

Channel Prot. outlet

Overbank outlet

Outlet riser

Defining EnhancedMethodologyDefining EnhancedMethodology

Continuous Simulation Analyses Performed to Ascertain Performance

Continuous Simulation Analyses Performed to Ascertain Performance

Hydrologic Processes SWMM Representation

runoff

precipitation

evapotranspiration

infiltration

BMP

Development area

Precipitation (hourly)

Surface runoff hydrograph

ETInfiltration

GW recharge

ET

Impervious areas(runoff block)

Precipitation (hourly)

Stormwater runoff

hydrograph

BMP (Storage treatment block)

Outflow hydrograph (to receiving waters)

Pervious areas(runoff block)

Disconnected runoff

Base flows (not considered for Burgundy Rose)

Hydrologic Processes SWMM Representation

runoff

precipitation

evapotranspiration

infiltration

BMP

Development area

runoff

precipitation

evapotranspiration

infiltration

BMP

Development area

Precipitation (hourly)

Surface runoff hydrograph

ETInfiltration

GW recharge

ET

Impervious areas(runoff block)

Precipitation (hourly)

Stormwater runoff

hydrograph

BMP (Storage treatment block)

Outflow hydrograph (to receiving waters)

Pervious areas(runoff block)

Disconnected runoff

Base flows (not considered for Burgundy Rose)

Precipitation (hourly)

Surface runoff hydrograph

ETInfiltration

GW recharge

ET

Impervious areas(runoff block)

Precipitation (hourly)

Stormwater runoff

hydrograph

BMP (Storage treatment block)

Outflow hydrograph (to receiving waters)

Pervious areas(runoff block)

Disconnected runoff

Base flows (not considered for Burgundy Rose)

Median particle size distribution

35%

40%

45%

50%

55%

60%

65%

70%

75%

80%

85%

90%

95%

100%

0.5 2.0 3.5 5.0 6.5 8.0 9.5 11.0 12.5 14.0 15.5 17.0 18.5 20.0

WQv (af)

% P

arti

cula

te P

ho

sph

oro

us

Cap

ture

25% PP - 24hr drawdown 25% PP - 48hr drawdown 25% PP - 72hr drawdown

50% PP - 24hr drawdown 50% PP - 48hr drawdown 50% PP - 72hr drawdown

Current design standard (WQv = 1.35 ac-ft)

1-year 24-hour (WQv = 5.33 ac-ft)

2-year 24-hour (WQv = 8.08 ac-ft)

Wet Extended Detention Pond (Particulate Phosphorous Treatment)

Extended Detention PondExtended Detention Pond

1yr

- Im

pe

rv

2x1

yr

- Im

pe

rv

2p

ctI

A -

Im

pe

rv

2yr

- Im

pe

rv

4x9

0p

ct

- Im

perv

DE

C -

Im

pe

rv

NY

CD

EP

- Im

pe

rv

1yr

- P

erv

2x1

yr

- P

erv

2p

ctI

A -

Perv

2yr

- P

erv

4x9

0p

ct

- P

erv

DE

C -

Perv

NY

CD

EP

- P

erv

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Particulate-associated Phosphorus

% P

art

icu

late

Ph

osp

ho

rus C

ap

ture

1yr - Imperv 2x1yr - Imperv 2pctIA - Imperv 2yr - Imperv 4x90pct - Imperv DEC - Imperv NYCDEP - Imperv

1yr - Perv 2x1yr - Perv 2pctIA - Perv 2yr - Perv 4x90pct - Perv DEC - Perv NYCDEP - Perv

Impervious Pervious

Infiltration SystemsInfiltration Systems

DE

C -

Im

pe

rv

1y

r -

Imp

erv

2y

r -

Imp

erv

DE

C -

Pe

rv

1y

r -

Pe

rv

2y

r -

Pe

rv

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Infiltration System Sizing Method

Perc

en

t fl

ow

vo

lum

e t

reatm

en

t

DEC - Imperv 1yr - Imperv 2yr - Imperv DEC - Perv 1yr - Perv 2yr - Perv

Impervious Pervious

• 1 year-24 hour Sizing Method estimated to achieve > 80% treatment for both storage and flow through systems.

• Decreasing marginal gain in treatment performance as WQv size increases

• Results in– Alternative that modifies WQv sizing– Use of TR-55/TR-20 methods– Incorporate physical characteristics of the site

RecommendationRecommendation

Performance Goals: source controlPerformance Goals: source control

Goal 1 - Reduce runoff volumes to the maximum extent practicable– Hydrologic Source Control– Evapotranspiration– Infiltration

• Infiltration Requirement– Infiltration credit– Incorporate soil in sizing– Site evaluation

Percentage of Impervious area routed through BSD

Hydrologic Soil Group

% Impervious area

A

30%

B

20%

C

10%

D 5%

Performance Goals: source controlPerformance Goals: source control

• Evaluation Requirements

– Imp. area disconnection

– Standard Infiltration

– Better Site Design– Low Impact Development– Green infrastructure– Sustainable Ecosystem

Better Site DesignBetter Site Design

Preserve undisturbed areas

Conservation Design

An approach to development An approach to development design design

that seeks to:that seeks to:

Better Site DesignBetter Site Design

Reduce impervious cover

Roads Parking lots Driveways

An approach to development An approach to development design design

that seeks to:that seeks to:

Better Site DesignBetter Site Design

Use pervious areas for stormwater treatment

An approach to development An approach to development design that seeks to:design that seeks to:

Performance Goals: source controlPerformance Goals: source control

• Post Construction

– Increased Curve Number– Soil Decompaction

• Deep Ripping• Decompaction

• Resourceshttp://www.dec.ny.gov/chemical/8694.html

• Goal 2 - Achieve less than 15% effective treatment bypass of the long term runoff volume.– Focus on hydraulic control– Capture and treatment– Bypass

• Simulated hydraulic function in SWMM• Applied design in TR-55, TR-20

Performance Goals: sizing criteriaPerformance Goals: sizing criteria

Sizing CriteriaSizing CriteriaSizing Criteria for Enhanced Phosphorus Removal

Water Quality (WQv)

WQv = estimated runoff volume

(acre-feet) resulting from the 1-year, 24-hour design storm over the post development watershed

Evaluate and implement hydrologic source control where feasible

Quantity Controls (Cpv, Qp, Qf)

Refer to existing requirements

ApplicationApplication• Precipitation Data

– Source of Isographs of Design Storms• TP-40• North East Climate Center Atlas of Precipitation Extremes

– Storm distribution

• Examples– Storage– Flow through– BSD

Good Drainage ParadigmGood Drainage Paradigm

Conventional Site DesignConventional Site Design

Collect Collect Concentrate Concentrate Convey Convey Centralized Centralized ControlControl

Credit: HWG

Rain Garden Rain Garden

Treatment Train ApproachTreatment Train Approach

Bioretention CellStorm Drain System

Bioretention CellFlow Path

Grass Swale Grass Filter Strip

Credit: HWG

Quantity ControlsQuantity Controls

• Channel Protection– 24 hour detention of 1 year, 24 hr storm

• Integrated in extended detention systems

• Need additional storage in flow through systems.

• Flood Control– 10 & 100 year control not exceeding pre

construction peak discharge.

• Goal 3 – median effluent concentration of particulate phosphorus shall be at or below 0.1 mg/L

• Goal 4 - median effluent concentration of dissolved phosphorus shall be at or below 0.06 mg/L– Effluent quality of the discharge– International Stormwater

BMP Database

http://www.bmpdatabase.org– Research by Pitt, et al.

(NSWQ Database)

http://rpitt.eng.ua.edu/Research/

ms4/Paper/Mainms4paper.html

Performance Goals: performance criteriaPerformance Goals: performance criteria

Performance Goals: performance criteriaPerformance Goals: performance criteria

• Performance Specifications: design details not specified in this section shall, at minimum, meet spec. in Chapter 6– Practice options– Design geometry– media specification– optimum vegetative cover– Maintenance

SummarySummary• An effective and technically defensible

criteria to address stormwater design standards in P-limited watersheds consistent with NYCDEP requirements – 1 year-24 hour Sizing Method estimated to

achieve > 80% treatment for both storage and flow through systems.

– Effluent concentration criteria – Hydrologic source control

• Better Site Design• Infiltration requirement

– Improved design specifications– TR-55 calculation method– Update precipitation values

Questions?Questions?

Shohreh Karimipour, P.E.sxkarimi@gw.dec.state.ny.us

(518) 402-8102