Como Park Stormwater BMP Projects

Como Park – An Urban Getaway

Como Regional Park is a popular destination for Minnesotans. Though it’s nestled in an urban neighborhood, park-goers feel like they’ve stepped into a scene far from the city. Every year, 1.9 million visitors enjoy peaceful mornings on the golf course, afternoons at the zoo, evening meals in the park’s pavilion, or taking a stroll around Como Lake.

Unfortunately, the park’s serene atmosphere can’t make up for the negative effects urban stormwater can have on Como Lake. Pollution from phosphorus in stormwater is the cause of harmful algae blooms seen in many of Minnesota’s lakes. Como Lake is one water body that has a long history of poor water quality due to excess phosphorus.

Project

In 2016, Capitol Region Watershed District (CRWD) and the City of Saint Paul partnered to find solutions to protect and improve the water quality of Como Lake as well as serve Saint Paul residents. They were awarded a $1.76-million grant through the Minnesota Board of Water and Soil Resources’ (BWSR) Targeted Watershed Program, which is funded by the Clean Water, Land, and Legacy Amendment to complete this work.

The CRWD hired HEI to complete a watershed assessment to identify treatment solutions that would solve both needs.

During this assessment, our team took inventory of storm sewers running through the park, completed a water quality study of surface runoff, calibrated stormwater models, and analyzed total suspended sediment (TSS) and total phosphorous (TP) pollution from the Como Lake Watershed. From this assessment, our team developed the Como Park Stormwater Master Plan to guide project partners in the next phase of their project.

The Stormwater Master Plan is a collaborative roadmap for the CRWD and the City to improve Como Lake’s water quality while meeting regulatory requirements. Its overall goal is to determine the most cost-effective way to meet the 1.1-inch volume reduction goal for runoff as well as remove 60% of TP entering the lake. It outlines the project partners’ goals and analyzed various implementation solutions to achieve those project goals. It also identifies best management practices (BMPs) that will restore the rainwater cycle as it soaks into the ground. It identified the fact that large-scale treatment is more cost-effective than site-by-site treatment, leading the way to several stormwater BMP projects. Once implemented, the Plan will meet the CRWD’s and City’s stormwater goals.

Every Plan Needs Action

With the Stormwater Management Plan as a guide, project partners began several projects to reach their stormwater goals. One was a feasibility study to determine the optimum locations and types of BMPs throughout Como Regional Park.

Due to our familiarity with the park’s stormwater and partner goals, HEI evaluated the BMPs in part for their potential to treat stormwater. Many locations were chosen due to their proximity to anticipated park improvement projects. These BMPs could then satisfy regulatory stormwater treatment requirements for upcoming City projects as well as provide the opportunity for large-scale treatment above and beyond those requirements.

After a detailed analysis, surveys and soil borings, utility coordination, and an on-site meeting with project partners, our team could envision several potential BMPs for Como Park. These BMPs included iron-enhanced sand filters (IESFs) because of their ability to remove dissolved phosphorous. After project partners provided input on their preferred BMP locations, we recommended specific BMPs and treatment trains based on their cost-effectiveness and ability to meet the Stormwater Management Plan’s goals.

Como Zoo and Golf Course

Once the CRWD accepted the feasibility study and recommended BMPs, it was time to make the plan come to life. Due to our in-depth knowledge of this project, the CRWD hired HEI to design the Como Zoo and Golf Course BMPs in 2018. The design incorporated the needs of numerous stakeholders throughout the project, including the Como Golf Course and golf course architect, Saint Paul Parks and Recreation, Saint Paul Sewer Utility, Como Zoo, and the CRWD. The final BMPs included: (1) the Northwest Golf Pond IESF along hole 3, (2) the Zoo Infiltration Basin, and (3) an underground infiltration system along hole 7.

The Design

A geotechnical evaluation was completed to pinpoint the best soils for infiltration. HEI also completed an existing conditions survey and topographic site survey to identify the location and elevation of storm sewer, utilities, slopes, trees, and existing site features for the design. Also, a survey of the pond bottom helped determine if the existing ponds will provide adequate pretreatment and sediment capacity before flows reach the IESFs. Because the BMPs are retrofitted in these existing ponds, they ensure the highest possible water quality improvements while maintaining a playable area on the golf course.

Based on project developments, HEI performed a wetland delineation and an additional ecological analysis of the site to understand the effects that the climate is having on local groundwater and ensure the golf course and groundwater wouldn’t be negatively affected by the proposed BMPs. Once our team collected this information, we updated an existing XPSWMM model to ensure the proposed BMPs would not negatively impact the existing, complex pipe hydraulics surrounding the BMPs.

To ensure the design included stakeholders’ goals, HEI submitted them at 30%, 60%, and 90% completion.

These innovative BMPs feature an automated valve that controls the ponds’ water elevation. The valves use water surface levels and weather forecasting to lower or raise the pond storage, which promotes water quality performance and flood mitigation. The valve can also be remotely controlled.

The Como Zoo BMP and the Northwest Golf Pond IESF were constructed in the fall of 2020.

Como Parking Lot Stormwater and Parking Lot Design

The City of Saint Paul is leading efforts to design and construct additional BMPs in the Como Parking Lot, as recommended in the feasibility study. The City hired HEI to design these BMPs to meet the Como Regional Park Stormwater Master Plan’s goals. Aesthetics and function come together in these BMPs by using water as a resource and amenity with features for park visitors to enjoy.

HEI developed two alternatives for each lot maximizing the utility for parking and community programming. Our planning team helped facilitate conceptual discussions between design engineers, the City’s landscape architects, and the CRWD to ensure the project benefits both Como Park visitors and Como Lake.

Our planning team helped facilitate conceptual discussions between design engineers, the City’s landscape architects, and the CRWD to ensure the project benefits both Como Park visitors and Como Lake.

View our interactive StoryMap to view photos, videos, and maps of this project.