overview of bmps, lid, and treatment trains...2018/09/07  · hydria, 1997 low impact development...

z FSA September 2018 Seminar

Overview of BMPs, LID, and Treatment Trains

Presented by

Elie G. Araj, PE, CFM, D.WRE

Current World Population 7,647,869,821

TODAY Births today 257,196

Deaths today 106,529

Population Growth today 150,667

Source: worldometers.info

Source: Florida Chamber

• CHANGES IN LAND USE

• DEVELOPMENT IN FLOODPLAINS

• ALTERATION OF NATURAL CONVEYANCE SYSTEMS

• COMPACTION OF SOIL, INCREASED IMPERVIOUSNESS

• “DRAINAGE” SYSTEMS

• ADDITION OF POLLUTANTS

The Stormwater Problem: Humans Cause…

Good Drainage Approach

The Problem: Conventional Site Design

Efficiency

Collect

Concentrate

Convey

• Spend $$ on repairing the damage after the fact

• Don’t allow growth in impaired basins

• Local governments require development to

treat a bigger portion of pollutant load

• State to modify existing stormwater rules to

include volume requirements

• Otherwise…

The Stormwater Problem: Possible Solutions…

The Stormwater Problem: Another Possibility…

An innovative stormwater management approach with a basic principle that is

modeled after nature.

1. Encourage Conservation

2. Minimize Impact

3. Strategic Runoff Control

4. Integrated Management

5. Pollution Prevention

LOW IMPACT DEVELOPMENT

Storing

Filtering

Infiltrating

Evaporating

Evapotranspiration

LID Processes

Conventional Low Impact

Design vs. Development

Local

Source Control

Preservation

Retention

• Regional

• End-of-pipe

• Improvement

• Detention

Conventional vs. LID

LID Processes

1. Widely Distributed

(smaller scale and single lot level)

2. Sub-Regional

(neighborhood scale)

3. Watershed Scale

LID Processes

LID + BMP = ERP

(SWFMD circa 2007)

Initial Regulatory Hurdles

LID = BMP = ERP

Initial Regulatory Hurdles

HYDRIA, 1997

LOW IMPACT DEVELOPMENT (LID) ELEMENTS

1. Infiltration/Filtering Systems: Rain Gardens Street Side and Bump-out Planters Green Gutters Tree Boxes Swales Living Shorelines Media Filters 2. Permeable Pavements:

Parking Lots Complete Streets

3. Green Building Technologies Green Roofs Green Walls Cisterns and Rainwater Harvesting

BIORETENTION IN PARKING LOT

Bioretention/Rain Gardens

Retention Volume

Time

Flo

w R

ate

Target Peak Flow Rate

Resulting Hydrograph (Tail portion only)

Site Drainage Hydrograph

Bioretention: Runoff Volume Reduction

SANDY SOIL

MULCH

INFILTRATION

EVAPOTRANSPIRATION

PLANTS

Source: PGDER

DRAIN

NATIVE SOIL

RAINFALL

GROUNDWATER RECHARGE

RUNOFF

DE-NITRIFICATION

Bioretention/Rain Gardens

Green Gutter Green Gutter

Green Gutter Green Gutter

Green Gutter Green Gutter

Green Gutter Green Gutter

Green Gutter Green Gutter

Green Gutter Green Gutter

Filterra/Tree Boxes

Biodegradation

2” Mulch

Sandy Filter Media

Drain Pipe

Storm Drain

Roadway

Optional Infiltration Storage

Volatilization

BioretentionClean-out

Rip-Rap

Root Uptake

Drains to infiltration storage

Tree Grate

Effectiveness:

ANNUAL VOLUME TREATED ANNUAL VOLUME: 85% - 90%

POLLUTANT REMOVAL

TP 70% - 74% TSS 80% - 95% TN 64% - 68% METALS 78% - 82%

APPROX. COSTS - $28,000+/- ACRE OF DRAINAGE AREA

Filterra

Pervious Concrete

• Proper installation techniques essential

• No high traffic • No tight turning

Pervious Pavement Calculator

Pervious Pavement Calculator

Pervious Pavement Calculator

Stormwater.ucf.edu

Permeable Pavers Permeable Pavers

Notice the difference in gaps between impervious and pervious pavers

Both pavers underlain with storage reservoir

Varying Types of Pervious Pavers

Concerns about heels getting caught

Governments seem particularly risk averse.

PF Chang’s changed City of Sarasota attitude. Now pavers are OK.

Liability Concerns

Porous Pavement Costs

Soil Amendments

IMPROVED INFILTRATION

IMPROVED AERATION

REDUCED EROSION

REDUCED COMPACTION

INCREASES VEGETATION ESTABLISHMENT

INCREASED NUTRIENTS

INCREASED MOISTURE RETENTION

Amendments are conditioners that are well mixed into the soil

Soil Amendments

Stormwater Reuse

• Irrigation Source – Saves Potable Water

• Significant Pollutant Load Reduction – TMDL Credits

• Restores the Hydrologic Cycle

Stormwater Reuse Design

• DEVELOP WATER BUDGET INVOLVING IRRIGATION RATES

• WATER BUDGET TO INCLUDE CONTINUOUS SIMULATIONS USING HISTORIC RAINFALL DATA FOR SPECIFIC LOCATION

• CALCULATE ∆ POND STORAGE TO PROVIDE IRRIGATION DEMAND

Stormwater Reuse Design

• CONCERNS OVER TOXICITY OF IRRIGATION AEROSOLS

• CERTAIN ALGEA AND BACTERIA CAN CAUSE RESPIRATORY/HEALTH ISSUES

• USE SAND FILTER

Pump

To Irrigation

48”

Typical Stormwater Reuse Pond

Re: Dr. WANIELISTA

CYANOBACTERIA - USE SAND FILTER

Typical Stormwater Reuse Pond

City of Largo – Bayhead Park Low Impact Development (LID) Development Retrofit

173 Acres Basin Draining to two (2) ponds in Downtown City of Largo

Stormwater Harvesting deployed in lieu of classical water quality treatment

First SWFWMD ERP Permit of its kind

Owner: City of Largo, FL

Stormwater Reuse Example

Living Shorelines

UCF – New Student Union Building Green Roof/Cistern Study

Green Roofs

UCF Student Union Expansion with 1600 Sq Ft Green Roof

LID techniques used included: Green roof

Cistern

UCF Green Roof/Cistern Study

TN load lower

NH3 load lower

TP & OP load lower

TSS load lower

NO3 load lower

Different growing media produce different results

Cistern receives runoff from the roof

Roof vegetation irrigated from cistern

Reduction of volume of surface water runoff by 87% for Orlando

UCF Green Roof/Cistern Study Findings:

Ottawa Roof Top Garden/Park

Montreal Roof Top Garden/Park

Roof Top Garden/Park

Roof Top Garden/Park

Roof Top Garden/Park

Cisterns

Green Roofs…Possibilities are Endless..

ENGINEERED END OF PIPE

FOCUSES ON CONTROLLING PEAK FLOW RATE AND SUSPENDED SOLIDS

FAILS TO ADDRESS CUMULATIVE HYDROLOGIC ALTERATIONS THAT CAUSE INCREASES IN STORMWATER VOLUME AND RUNOFF RATES & CAUSE EXCESSIVE EROSION AND DEGRADATION OF STREAM CHANNELS.

OFTEN DOESN’T TREAT NUTRIENTS WELL

LID CAN COMPLEMENT CONVENTIONAL TECHNIQUES BY REDUCING VOLUMES AND PEAK FLOW RATES ALLOWING FOR SMALLER CONVENTIONAL INFRASTRUCTURE, PIPES, PONDS, ETC.

Conventional Stormwater Management

Conventional Land Development Review

Simple Mowing is Often Difficult…

FACILITIES ARE NEW, HAVEN’T MAINTAINED THEM BEFORE LONGEVITY? COSTS?

NEED TRAINING AND MAY NEED EQUIPMENT

OFTEN ELIMINATE TREES FOR EASE OF MOWING/MAINTENANCE

LANDSCAPING NEEDS MAINTENANCE ANYWAY…DOES IT REALLY COST MORE TO MAINTAIN IF IT’S LID? OR DOES ANOTHER DEPARTMENT MAINTAIN “LANDSCAPING”? A QUESTION OF WHO PAYS/BUDGETS?

NEED A BUDGET PROCESS THAT INCREASES FOR NEW CIPS

GREEN INFRASTRUCTURE SERVES MANY FUNCTIONS: AESTHETICS, SHADE, RAINFALL INTERCEPTION, BUFFER, ETC….. NEED INTEGRATED CROSS DEPARTMENT BUDGET

Maintenance Concerns

Questions: Elie Araj, PE, CFM, D.WRE Applied Sciences Consulting earaj@appliedfl.com