Grantee Research Project Results
Final Report: Evaluating Biofiltration in Small Urban Areas: Chico, California Case Study
EPA Grant Number: SU835992Title: Evaluating Biofiltration in Small Urban Areas: Chico, California Case Study
Investigators: Matiasek, Sandrine
Institution: California State University - Chico
EPA Project Officer: Page, Angela
Phase: I
Project Period: September 1, 2015 through August 31, 2016
Project Amount: $14,963
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2015) RFA Text | Recipients Lists
Research Category: P3 Awards , Pollution Prevention/Sustainable Development , Sustainable and Healthy Communities , P3 Challenge Area - Safe and Sustainable Water Resources
Objective:
The overall goals of the proposed research are to improve water quality in small urban cities and campuses and increase awareness about urban green water infrastructure by identifying the practicality of using biofiltration in small urban areas, using the City of Chico and CSU Chico campus as model sites. This requires identifying preferred configurations, evaluating performance of filter media to both remove pollutants and withstand harsh weather conditions, performing a cost-benefit analysis comparing biofiltration to other stormwater runoff BMPs, and disseminating results to the local community using K-12 outreach and meetings with local officials. This research embodies the principles of sustainability and seeks solutions that protect the environment and strengthen communities.
These tasks will be accomplished by a series of laboratory experiments and by performing a life cycle analysis. The project team will design and construct laboratory biofiltration systems out of PVC pipe and other inexpensive materials. The biofilters will use native, drought-resistant, sun-tolerant plants chosen to represent local conditions. Short-term experiments will examine a variety of physical design factors for biofiltration systems (e.g., infiltration rate; combinations of various filter media) and further investigate plant species suitable for biofiltration based on climate conditions. The team will also summarize, generalize and disseminate results to non-technical audiences so that findings are valuable to other small urban areas and campuses.
Summary/Accomplishments (Outputs/Outcomes):
The team examined theoretical benefits of biofiltration systems through a literature review and consultations with the current president of the local branch of the American Society of Civil Engineers (ASCE). They gained applied knowledge of an existing biofiltration project through their involvement in the revegetation of the Biofiltration Wetland Educational Living Laboratory (BWELL) bioswale at the local community college, Butte College.
To best design laboratory tests, stormwater runoff was sampled at two locations on CSU Chico campus and characterized chemically with a suite of analyses. Water quality of stormwater on CSU Chico campus was good overall, except for a few elevated metals found above Environmental Screening Levels defined by California EPA.
Biofilter test columns were built out of PVC pipe capped at one end and equipped with a drain pipe. All biofilters consisted of the following layers, starting at the bottom: 2 cm of pebbles (for drainage), 1 cm of fine sand (for particles retention), 22 cm of “filtration mix” (test variable), 10 cm of mulch, 3-4 sedges, and a monolayer of lava rock (to prevent mulch erosion). The
“filtration mix” was one of five combinations of coarse playground sand and soil. These five filter media combinations were built in triplicates for a total of 15 biofilter columns.
The infiltration rate of the constructed biofilters was evaluated. Water drainage was found to be fastest in the biofilters made of sand only, while mixtures of sand and oil resulted in slower drainage. Compaction of filtration media was identified as a key parameter during the construction of biofilters. Additional tests were recommended to better understand important design factors, since compaction is unavoidable during construction of biofiltration systems. Further testing is also necessary to study the effects of repeated storms (biofilter resiliency over time) and of high sediment concentrations in stormwater on biofilter infiltration capacity.
The effect of biofiltration on stormwater composition was evaluated during laboratory tests. A synthetic storm runoff was prepared based on the composition of stormwater sampled on CSU Chico campus. Synthetic runoff was applied to the biofilter test columns composed of various combinations of sand and soil mixtures in their filtration layer.
Biofilters were generally very successful at improving stormwater quality and there were few differences between filter media combinations. The biofiltration process neutralized and aerated storm runoff, which contribute to beneficial conditions for aquatic life. Although salinity was increased by biofiltration, it stayed within an acceptable range for aquatic organisms. Turbidity decreased in all biofilters, except in the columns with filtration layers made of pure sand. The sand filters also released additional nitrate and phosphate in the synthetic runoff, which could have strong negative impacts on aquatic ecosystems. All biofilters efficiently removed ammonium and metals from the synthetic stormwater, even when working with synthetic stormwater with concentrations orders of magnitude larger than concentrations measured in campus stormwater.
Due to time limitations, plant tests and the life cycle analysis will be accomplished during the second part of Phase I. The team presented their results at “This Way To Sustainability” Conference on March 25, 2016 at CSU Chico. They will also formally present their results to the campus Sustainability Committee and City of Chico officials in May and August 2016. Outreach activities will be prepared and implemented for various audiences at the National Sustainable Design Expo in April 2016 and at the CSU Chico Hands-On Lab (grades K-9). For these educational outreach events, a biofiltration infographic will be prepared and hands-on demonstrations will be conducted. Finally, the “Biofiltration Guidelines for Small Cities” guidance pamphlet and a final project report will be prepared during the summer.
Conclusions:
Over the first 6 months of Phase I of the project, the student team successfully examined the theoretical benefits of biofiltration systems, identified critical design factors, and determined effective media combinations with a series of laboratory experiments. Results from Phase I demonstrated that biofiltration systems offer quantifiable benefits to people, prosperity and the planet. Biofilters were able to remove over 98% of the metals copper, nickel, and zinc. Stormwater quality was generally improved during biofiltration, resulting in decreased turbidity, neutralized and oxygenated water, which directly improve the health of aquatic ecosystems. Increased water quality not only benefits aquatic organisms, but also provides economic benefits to downstream urban and agricultural users, reducing drinking water treatment costs and pollutant impacts on crops in the agricultural Central Valley. To further our understanding of key biofilter design parameters necessary to achieve a performing system, a more in-depth characterization of pollutant fate in filter media and plants is necessary. Similarly, long-term experiments assessing the resiliency of biofiltration systems are critical to identifying the key components to a sustainable design for this green urban water infrastructure.
Supplemental Keywords:
storm water management; water treatment technology; urban water planning; water filtration; pollutant removal; bioretention; low impact development; best management practices; ecological; hydrological; water cycle; cost benefit assessment; environmental education.P3 Phase II:
Evaluating Biofiltration in Small Urban Areas: Chico, California Case Study | 2017 Progress Report | 2018 Progress Report | Final ReportThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.