PRESENTER:Debbie Stringer

Stormwater BMP Construction I&M , Horticulturist

Using ASTM C330 Expanded SlateSand to Meet NC DEQ Guidelines for

Bioretention Media

ASTM C330: Structural LWAggregate – Shale, Clay and Slate

North Carolina has meta-argilliteThe slate is formed from volcanic ash which was deposited in a

wet environment and compressed under extreme pressures formillions of years. The slate deposit is located in the foothills east

of Charlotte.

Conveyance toRotary Kilns

Extraction ofRaw Material

Crushing, Grading, Screening,Washing, then to QC Lab

CharacteristicsPorosity 49%

Bulk Density 58lbs/ftᶾ

Relative Density (SG) 1.88

Absorption 11-12%

Compressive Strength 38,000 lbs/ft² (fines)41,000 lbs/ft² (coarse)

CEC Coarse 26 me / 100g

CEC Fines 10-12 me / 100g

Heavy metals < 0.01mg /L

pH 8.5 stable More Angularity& Surface Area

9

Washed medium coarse sand 75-80%blended with

Fines (silt / clay fraction) 12-13%

Organic Matter - pine bark10-20% by volume

(5-10% by compressed weight)(3-6% by combusted dry weight)

ASTM C330 Bioretention Media

HydraulicConductivity

Ksat @ 20° C

cm/sec cm/hr in/min in/hr

With 100%Standard Proctor

Compaction(ASTM D 5084)

0.0006 2.16 0.015 0.9

WithoutCompaction

(ASTM D 2434)0.012 41.4 0.27 16

Compaction byboots, equipment

and weather

C330 Research with SCMs

First IWS in NCNCSU BAE Research 2005

Graham HS, Graham NC

N. Mecklenburg Recycling Center 2009

C33 80% Sand / 15% silt clay / 5% compost C330 80% Sand / 20% compost

UNCC Bench-Scale Column Testing2011-2012

1000 mL synthetic stormwater solution fed to each column3.33 mg/L PO₄-P 1mg/L NO₃-N

(1-2) Batch Feed Method:Bottom valve closed for 12 hours of contacttime between the solution and the filtermedia

(3-4) Gravity Flow Method:Bottom valve closed for 30 minutes, then

opened to allow solution flow throughmedia

Removal RatePO₄-P 82% 97% 98% 58%

NO₃-N 65% 0% 0% 70%

NCSU ResearchJC Raulston Arboretum, Raleigh

June 2011 - July 2012

NCSU Substrate ResearchSecondary source runoff pond pumped to an irrigation pit

supplemented with:50 mg/L-1 N (supplied by dissolved ammonium sulfate, 21-0-0)

50 mg/L-1 P (supplied by dissolved diammonium phosphate 18-46-0)

Actual Nutrients in Stormwater + Fertilizer applied:80.9 ± 22.1 mg/L¯¹ N14.6 ± 5.5 mg/L¯¹ P

March 2011-July 2012

Season 1 Dormant Season Season 2

Leachate Averages N mg/L¯¹ P mg/L¯¹ N mg/L¯¹ P mg/L¯¹ N mg/L¯¹ P mg/L¯¹

‘Slate’ media 17 ~1.0 8 0.9 ~10 0.6

‘Sand’ media 30.1 ~3.0 13 ~3.0 ~10 0.6

‘Soil’ media 17 3.4 8 2.8 ~10 0.7

Life CycleC330 Resilience

Elon University

Hunt Softball Complex at Williamson Ave., Elon Univ. 2011-12

Elon University 2019

Northlake MallCharlotte NC

2005-2019

NCDOT ‘High Flow’Infiltration Basins

Manages hydraulic loadsStable – load-bearing for incidents and maintenanceResists over-compaction

Industrial StormwaterSludge Drying Bed Media

C330 Projects

The Read Building, Falls Church VA2007- present

Bioretention Cell between the Read Building and the Exxon station is 5’ deep

Transylvania Co. Public LibraryBrevard NC 2005 - present

Cells that are 4’-6’ deep in the NC mountains require a mediathat will not clog

Turf Bioretentionin WNC

Borg Warner, Arden NC

Empire Distributors, Arden NC

Richmond Hill ParkAsheville, NC

Spring 2009

Fall 2017 after 4” rain in the last 24 hours

NC ArboretumFletcher NC

2008-2019

C330 in Urban SCMs

Rain Catcher ProjectDurham NC

Downspout Disconnect2011 2017

For the Ellerbe Creek watershed

Urban RetrofitsTraffic Calming / Bioretention in Raleigh NC

Milburnie Road & Chatham Lane 2019

High Flow Tree WellsChatham Park, Pittsboro NC

NCSU Artists BackyardRaleigh 2011-2019

2015 BUBBA winner! Best Urban BMP outside the Chesapeake Bay watershed

Moore Square Raleigh 2019

Not bioretention,however, it isengineered with C330sand media to infiltrateand store moisture aswell as resist over-compaction

• Infiltration rates handle peak flows• Improves water quality• Long life cycle• Root zone re-aeration• Broad plant palette for designers• Manufactured in North Carolina• Nutrient trading? Bioretention and

constructed wetlands offer the highestreturns

C330 Bioretention Benefits

C330 Expanded Slate BlendedBioretention Media

FOB Aquadale, NC

$54.00 per ton @ 0.78 tons / CY= $42.00 per CY

One 25 ton bulk dump trailer =32 CY of C330 bioretention media

More Info:Debbie Stringer dstringer@stalite.comChuck Friedrich cfriedrich@stalite.com