Metra Park, Billings - Stormwater and Nutrient Trading Evaluation Project

Project Location:  Metra Park, Billings, Montana USA
A BioHaven® Floating Island (floating treatment wetland/FTW) installed in the City of Billings Metra Park stormwater pond has very effectively removed metals, nutrients and other contaminants, with removal percentages ranging from 63% to 98%. The BioHaven’s effectiveness substantially improved after its vegetation had matured for two growing seasons. The City of Billings was interested in FII technologies to meet MS4 stormwater requirements and the pending Numeric Nutrient Wastewater Standards.

---

In November 2008, City of Billings personnel constructed a pond to treat a portion of stormwater discharges originating from a 174-acre drainage dominated by light industrial and commercial properties.  A large BioHaven was installed in the Metra pond shortly after its construction, along with a smaller BioHaven in the channel preceding the pond.  The FTWs were planted with native grasses and other vegetation in May 2009.

Installation Data
Location:    Billings, Montana USA
Parameters Studied:    Total suspended solids, chemical oxygen demand, total phosphorus, total nitrogen, copper, lead, zinc, oil and grease

System Type:    Stormwater pond
BioHaven Size:     Area of 1500 ft2 (140 m2); thickness of 8 in. (20 cm)
Water Source:    Stormwater runoff from paved parking surfaces in industrial area of Billings
Installation Date:    Spring 2009
Flow Rate:    Variable, depending upon precipitation
Water Body Depth:    Approximately 4 ft (1.2 m)
Water Body Area:    3600 ft2 (330 m2)
% Coverage:    42% of pond covered by FTW

Operational Data
Average O&M Costs (Labor, Materials):    1 hour/month; no materials
Training Required to Operate:    1-day training seminar 
Additional Inputs:    None
Anticipated Lifespan:    At least 10 years 
Results 
The BioHavens were installed in late 2008 and planted with vegetation in early 2009; this vegetation became established in 2009 and 2010.  Billings has an arid climate so stormwater flow occurs infrequently.  Three samples taken in 2009 showed little removal of the eight contaminants measured.  However, two samples taken in late 2010 and early 2011, after the FTW vegetation had matured, showed dramatic contaminant reductions between the stormwater pond inlet and outlet.  Average concentrations from the last two sampling events are shown in the table below.

Please request the full Metra case study to view the stormwater pond results 
Percentage improvement:  
Total suspended solids (TSS) 93%
Chemical oxygen demand (COD) 88%
Total phosphorus (TP)  88%
Total nitrogen (TN)  72%
Copper  90%
Lead 95%
Zinc 94%
Oil & grease (O&G)  83%

Conclusions
The BioHaven installed in the City of Billings Metra Park stormwater pond has very effectively removed the eight contaminants monitored; removal percentages from the last two sampling events range from 63% to 98%.  The FTW’s effectiveness was substantially improved after its vegetation had matured for two growing seasons.  The large jump in treatment effectiveness from the first year of operation shows the effect of the BioHaven compared to the pond by itself.