George Hild Hild & Associates, Inc. River Falls, WI
Permitting and Enforcement The Dynamics are Changing! New developments: EPA proposal entitled “Effluent Limitation Guidelines and Standards for the Construction and Development Point Source Category.” Requires better focus and accountability on standard erosion and sediment control BMP’s. Recommends passive stormwater treatment to reduce turbidity if standard erosion and sediment control BMP’s are not enough.
Soil in our Water
Stormwater Sedimentation causes : Clogged stream channels. Increased bank erosion. Meandering and flooding. Sediment reduces storage capacity of reservoirs, destroys wetland areas, and degrades the quality of water used for municipal, industrial, and recreational uses.
Aquatic Habitat Impact Clean gravel streambeds become muddy bottoms. Native fish, insects, and animals disappear. Turbidity and suspended solids are toxic to aquatic organisms. Oxygen producing plants die off. Water temperatures increase.
Dishonorable Discharge
Now What? You have successfully retained your stormwater on site but… High NTU levels.
In Addition: Your stormwater is full of suspended clays and particulates that refuse to settle out on their own due to small size. untreated particle settling time – 1.0 mm coarse sand 10 seconds – 0.1 mm fine sand 125 seconds – .01 silt 108 minutes – .0001 colloidals 755 days Your infiltration basin isn’t functioning. You need to make room for more stormwater before the next rain event.
Stormwater Filtration and Site Dewatering Techniques
What is Biostar-CH? Chitosan (poly-D-glucosamine) Natural sediment flocculant. Second most common polymer in nature. Structurally related to cellulose. Found in the shells of crustaceans and certain other organisms such as fungi, algae, and yeast. Source: US EPA
Biostar-CH Non-toxic, non-hazardous, commonly used by commercial aquariums to clean water. Binds sediment particles within 30 seconds by reducing the zeta potential (electrical charge resistance). Creates larger flocs enabling filtration or gravity settling to occur. Breaks down to carbon dioxide and water within approximately 19 days. No bio-accumulation concerns.
Why Is Biostar-CH Needed? The application of Biostar flocculant aids in the reduction of turbidity by more efficient removal of fine suspended sediment. Biostar destabilizes colloids by neutralizing the forces (ionic charges) that keep the particles apart. Turbidity is difficult to control if fine particles are in suspension.
Biostar-CH When added in correct amounts, suspended colloidal particles combine resulting in an increased mass that is subject to accelerated settling by gravity. Selected BMP’s become more efficient filtration devices. The proper use of Biostar assists in ensuring that discharge waters from construction sites does not exceed the discharge requirements and permit conditions. Treated runoff with Biostar reduces toxicity by removing sediment.
What is passive stormwater treatment? Passive treatment does not replace conventional erosion and sediment control BMP’s. Augments/enhances existing BMP’s. Allows operation under discharge standards.
Field Testing Ph needs to be in the range of 6.5 – 8.5. Fill (2) one quart clear containers with target water. Jar #1 (control) Jar #2 add 1-2 drops of liquid Biostar or a pinch of the dry flake material. Mix vigorously for 10 -15 seconds. Allow to settle for approximately one hour and compare. Measure NTU’s with a meter or transparency tube.
Transparency Conversion Chart* Centimeters Inches NTU (approx.) <6.4 <2.5 >240 6.4 to 7.0 2.5 to 2.75 240 7.1 to 8.2 2.76 to 3.25 185 8.3 to 9.5 3.26 to 3.75 150 9.6 to 10.8 3.76 to 4.25 120 10.9 to 12.0 4.26 to 4.75 100 12.1 to 14.0 4.76 to 5.5 90 14.1 to 16.5 5.6 to 6.5 65 16.6 to 19.1 6.6 to 7.5 50 19.2 to 21.6 7.6 to 8.5 40 21.7 to 24.1 8.6 to 9.5 35 24.2 to 26.7 9.6 to 10.5 30 26.8 to 29.2 10.6 to 11.5 27 29.3 to 31.8 11.6 to 12.5 24
Transparency Conversion Chart 31.9 to 34.3 12.6 to 13.5 21 34.4 to 36.8 13.6 to 14.5 19 36.9 to 39.4 14.6 to 15.5 17 39.5 to 41.9 15.6 to 16.5 15 42.0 to 44.5 16.6 to 17.5 14 44.6 to 47.0 17.6 to 18.5 13 47.1 to 49.5 18.6 to 19.5 12 49.6 to 52.1 19.6 to 20.5 11 52.2 to 54.6 20.6 to 21.5 10 >54.7 >21.6 <10
Passive Dose Methods/Rates Floc 500 treatment bags will release a dose rate of approximately 2 ppm (ml/L) @300 gpm in a 4” diameter pipe or hose. Dry flake slowly turns into a gel. Bags will generally treat 100,000 gallons of stormwater. (5.5 hrs@ 300 gpm)
Flow rate/number of bags gpm low turbidity medium high 50-300 1 1-2 2 300-600 1-2 2 2 600-900 2 2-3 2-3 900-1200 3 3-4 4 1200-1500 4 4-5 5 *water temperatures below 40F require doubling of units.
Final Biostar Performance Determination Prior to floc 500 installation, pre-soak the units for approximately 30 minutes and then install in position. Start pumping system. After 5 minutes, sample pump water and observe for flocs. If floc is present, continue the operation. If no floc is present, add 1 additional floc 500 and repeat.
Floc Bag Design Geo textile Burlap
Floc Bag Applications “Pro - Active” Upstream Erosion Control Techniques BMP Enhancement
Floc Bag Applications BMP Enhancement
Floc Bag Applications BMP Enhancements
Floc Bag Applications BMP Enhancements
Design Inflow Values and Biostar Accompanying Concentrations Biostar is not soil specific but a representative water sample needs a ph of 6.5-8.5 Sediment yields vary depending on amount of unprotected land as well as the magnitude of rainfall Designers need to determine expected flows at each major inflow location to an SCS It is at these inflow locations/contact points where the introduction of Biostar is to occur in a manner that ensures optimal mixing.
Floc Bag Housing Unit Pump through mixing system. Allow 40-50 feet of mixing time prior to discharge. Y feature allows for easy bag replacement.
Floc Bag Housing Units Recommended for: Any pumping application where the introduction and mixing of Biostar is needed. Can be pumped to settling ponds, biofiltration areas, temporary holding setups, recirculation, and additional filtration equipment and mechanisms.
Liquid Biostar Injection Precise metered dose rates using a high viscosity injection pump.
Filtration Tanks 7000 gal capacity 300 gpm flow
Gravity settling tank/pond discharge to surface water
Pond Recirculation
Dewatering Bags
Storage/Settling Tanks
Sand Filters Chitosan Enhanced Sand Filtration (CESF)
Filtering/Polishing Down to 1 micron
Clean Water Discharge 3 ntu
Biofiltration Discharge Stormwater treated with Biostar, which cannot be treated with any methods due to insufficient capacity or for any other reason, can be discharged to the ground (overland flow) at a location which is at least 300 feet from the nearest surface water, in an area which is fully vegetated at the disposal location and over the entire pathway to a surface water. Allows for collection and bio-filtration of sediment flocs. Equipment: pump (2, 3, or 4”) suction hose (floating or skimmer) Biostar floc 500’s 50’ discharge hose perforated dispersal pipe (1’ of pipe for each gpm of output) Note: Connect the treatment assembly to the pressurized side of the pump (limit treatment flow rate to less than 300 gpm for best results)
Summary Wide range of effective methods ranging from passive treatment to Biostar (chitosan) enhanced sand filtration (CESF) technology. Selected treatment methods depend on site conditions, as well as discharge requirements and limits. Equipment solutions exist allowing for on site continuous discharge monitoring, record keeping, and permit compliance.
Thank You! Hild & Associates, Inc. George Hild www.biostar-ch.com www.ghild@hildandassociates.com
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