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Engineered Streambed for Enhanced Pollutant Removal


Urban stormwater runoff contains pollutants such as nutrients (nitrogen and phosphorus), pathogens (mainly E. coli and coliforms), and heavy metals that often come from anthropogenic activities such as fertilization, excessive irrigation, pet waste, degradation of vehicular parts, and industrial activities. Determining a way to effectively remove these pollutants is important as urban systems drain into larger water systems, such as Clear Creek, which is a drinking water source for not only Golden but also other municipalities downstream of Golden. Furthermore, high levels of pollutants entering into rivers impact the ecological health of the stream, potentially making it unsafe for wildlife and recreational activities such as kayaking and tubing. 

The A-Stream team’s project involves the design, development and implementation of a modular Biohydrochemical Enhancement Structure for Streamwater Treatment (BEST) system that will efficiently remove pollutants from an urban streambed in Golden, Colorado. The BEST system is a relatively new, experimental solution that is still being researched. Therefore, implementing the system would help to increase knowledge of the system’s functionality and potentially increase its widespread implementation in urban streambeds across the world.

The A-Stream Team Photos

Aerial view of the project stream, outlined in blue

The project stream is located between South Golden Road and Johnson Road in Golden, Colorado, and the system will be implemented in the straight portion of the channel, as shown in the map above. Follow the instructions below to see an up-close 3D view of the stream.

  1. Click and drag the yellow street-view character on the Google Map
  2. Drag the street-view character to the blue line over the stream location, as shown in the photo to the right
  3. Navigate with the mouse for a full visual of the project stream              


Interactive Google map of the project stream

Live Zoom Chat

Use the link below to join us live from 8:00 – 10:30 a.m. on April 29.

Please use link:

Or iPhone one-tap: 16699006833,95019610564# or 12532158782,95019610564#

Or Telephone:
    Dial: +1 669 900 6833 (US Toll) or +1 253 215 8782 (US Toll)
    Meeting ID: 950 1961 0564

Team Members

  • Madison Deter
  • Jaymee Donovan
  • Samuel Fiorica
  • Mattie McKinnis
  • Kimberly Riddle
  • Lilli Roberts

The Client

  •  Dr. John McCray, ReNUWIt



Project Advisors: Dr. Alina Handorean and Dr. Elizabeth Reddy

Technical Advisors: Mr. Adam Brady, P.E., and Mr. Casey Bernal, P.E.

Donations Made by: ReNUWIt

Special thank you to: ReNUWIt and Dr. John McCray for their sponsorship; the McCray Research Group including Brittnee Halpin and Forest Pilone; Tracey Pond (Stormwater Coordinator) and Joseph Lammers (Civil Engineer), from the City of Golden, for attending our presentations, providing constructive feedback, and hearing the ideas that could improve water quality draining into Clear Creek; Mr. Adam Brady and Mr. Casey Bernal for reviewing our calculations and designs; and our Project Advisors: Alina Handorean and Beth Reddy for providing us with everything that we have needed and being constantly encouraging and positive.



Elevator Pitch

Location of proposed BEST system implementation

The goal of this project was to design a passive, modular solution for stream water pollution due to storm runoff and dry weather flows. The project seeks to apply the research of Dr. John McCray and ReNUWIt to produce a scalable engineered streambed design that improves the overall quality of urban streamwater.

The problem at the core of this project is pollution associated with urban stormwater and dry weather flows. These events lead to increases of pollutants of concern – namely pathogens, nutrients, and heavy metals – due to common anthropogenic activities such as fertilization, excessive irrigation, pet waste, and industrial activities that take place between flow events.

The solution developed by the A-Stream team is a modular BEST system that will remove pollution from urban streambeds through geomedia filtration. The system was designed to be installed directly into urban streambeds, and the geometry promotes hydrodynamic processes that encourage infiltration of stream water through geomedia filters that capture pollutants of concern. 

Design Approach


The main deliverables for the scope of this project were determined to be: 

  1. Develop a BEST system design through research for the chosen project stream
  2. Evaluate the project stream through detailed site analyses 
  3. Make a plan for future implementation of the BEST system

Design decisions and methodology, and project site analyses can be found in the modules below.

Design Specifications

The following design specifications were set for the team based on client feedback from Dr. John McCray and the City of Golden, as well as from research on existing BEST system designs.

Site Analysis

Data from the National Land Cover Dataset (NLCD) was utilized to determine the land cover and imperviousness within the topological drainage basin. Most of the upper drainage basin (52%) consists of herbaceous land cover on South Table mountain; the land cover becomes more developed as it approaches the project site.

Where the land is more developed, there is an increase in imperviousness and associated stormwater runoff. The green of the imperviousness map represents little to no imperviousness meaning that the water is mostly absorbed into the ground, whereas the blue indicates higher levels of impervious surfaces and increased runoff. 

Land cover within the project site topological drainage basin

Percent imperviousness of land within the topological drainage basin










Storm pipes and waterways in Golden, Colorado

The Golden stormwater system exceeds the topological boundaries of the surface watershed and includes parts of Lakewood, Colorado near Colorado Mills Shopping Area and along 6th Avenue. Our study site includes both surface water runoff from the South Golden Watershed and stormwater entering from areas near West Pleasant View, Colorado. Our waterway can be seen in green draining northwest to Clear Creek from our study site. The additional stormwater that enters our area can be followed around the surface watershed shown on the map. 

The results of the site analysis indicate that more green infrastructure, such as the BEST system, should be implemented to decrease imperviousness and the associated surface runoff. Furthermore, because additional external stormwater enters our study site storm pipes, the implementation of BEST system in this stream is even more important for improving the water quality of the receiving water body, Clear Creek. 

Water Quality

Understanding the water quality of the project stream is necessary to assess the health of the stream and the potential downstream impacts to fish or human life. Going into the project, it was assumed that the main constituents of concern in the stream would be anthropogenically sourced nutrients (mainly phosphorus and nitrogen), bacteria (E. coli and coliforms), and heavy metals from stormwater runoff. 

The McCray Research Group, including Brittnee Halpin and Forest Pilone, have also worked on the project site for their own research; because water quality data was collected by the graduate students during the scope of this project, the client suggested that the team use the data instead of retesting the quality of the stream. The average values for all the collected data of interest to this project were calculated and compared to the US Environmental Protection Agency (EPA) and Colorado Department of Public Health and Safety (CDPHE) water quality standards. The average values are highlighted the color of any water standards listed that were notably exceeded.

The EPA Human Recreation and Fishing standard was chosen as a main comparison for the pH, conductivity, flow, bacteria, and nutrients because the standard was the best fit for the use of the project stream site. Metals constituents are more heavily regulated than other parameters, and are present in more standards. Thus, in addition to the EPA Human Recreation and Fishing standard, the EPA Aquatic Life Chronic and CHPHE Acute standards were applied for metals because of the potential impact on fish in Clear Creek over time, and the potential health hazard for human life if exposed for a short period of time to the stream (acute exposure). 

Based on the averages of the data, the stream exceeds water quality standards for bacteria (coliforms and E. coli) and metals (arsenic, copper, manganese, phosphorus, selenium, and zinc).

The measurements confirm that nutrients, bacteria, and metal concentration levels are of concern within the stream. Implementation of the BEST system could help to reduce the concentrations of these constituents and make the stream be in compliance with EPA and CDPHE water standards.

When choosing the geomedia for the BEST system, the A-Stream focused on bacteria filtration due to the significant exceedance in the project stream. All-purpose (0.5-1.0 mm) coarse sand was ultimately chosen for the overall accessibility and efficiency at removing bacteria from the water.


Design Solution

Solidworks Computer-aided Design (CAD) was used to design the modular BEST system. The system uses multi-purpose (0.5-1.0 mm) coarse sand geomedia to provide passive water filtration; the design was based on the research of ReNUWIt in order to maximize surface penetration of the entire geomedia filter.

Triangular baffling walls were chosen as a part of the design because they minimize dead spaces within the BEST structure and make flow path retention times more uniform. Additionally, the system allows for easy removal of the geomedia-baskets by maintenance workers so that the filter material can be changed on a regular basis. Detailed designs of the BEST system components can be seen below.

Visual assembly of the BEST System components

The solution is unique in that it can be manufactured-off site, thus requiring minimal construction time and site disturbance beyond site-preparation. Furthermore, the system’s modular nature allows it to be scaled to meet the specific needs of the site and the client. 

Design specifications set for the project by the client were fulfilled in the A-Stream’s design as outlined below. For reference of the design specifications, please refer to the Design Approach section above.


Next Steps

Due to the time constraints of this project, future work is necessary to validate the design of the BEST system through prototyping and implementation of the physical BEST system.

  1. Future students/groups can use the developed designs to prototype a single module as a validation of the proof of concept
  2. A push for implementation will be necessary to validate the usefulness of the BEST system
  3. Performing consistent water quality tests of the influent and effluent are necessary to determine the effectiveness of the BEST system implementation; should the streambed remove some of the constituents of concern, it would be considered successful in improving the water quality of the urban runoff corridor

Meet the Team

Madison Deter

Madi will be graduating with a degree in Environmental Engineering this May. She will be continuing her education at Mines and will receive a master’s degree in Hydrology and Water Resources Engineering in the spring of 2022. Madi has an intense passion for the environment and loves to spend her free time playing Ultimate Frisbee, hiking, camping, floating, and anything else that gets her outside. She is excited for the future and can’t wait to see what her and her peers accomplish.


Jaymee Donovan

Jaymee Donovan is a senior at mines studying Civil Engineering. On campus she is involved in the American Society of Engineering Management and the Pi Beta Phi Sorority. She enjoyed working on this project because it gave her an opportunity to work in the golden community. After graduation, she will be starting work as civil engineer in California.
Samuel Fiorica

Sam is a California native earning his bachelor’s degree in Mechanical Engineering. His interests include martial arts and entrepreneurship. Following graduation, he will be returning to Mines to finish a master’s degree in Engineering & Technology Management while working on his start-ups.
Mattie McKinnis

Mattie is graduating this May with her degree in Environmental Engineering. Everyday, you can find her spending time with her adorable new puppy, Peanut. After graduating, she will be starting her job as an Entry Level Environmental Engineer with Barr Engineering. 

Kimberly Riddle

Kim Riddle is a graduating senior in Environmental Engineering with a minor in Economics. As a natural band geek, Kim was involved with the Mines marching band and Rise Percussion during her time at Mines. She also likes to go for walks and spend time outdoors. Kim has loved her time with the A-Stream and on this project, and is thankful to have worked with such a great team.

Lillian Roberts

Lilli Roberts is a Civil Engineering student graduating in May, 2021. After graduation, she will be working for Ashely and Vance Engineering, Inc. in their Denver office. There, she will be a project engineer working on low impact development. She has really enjoyed being a part of the A-Stream in designing this product. She has gained valuable insight into project management and client interaction through this process.