What is an As-Built, and Why is it Important?

ACD recently led a project that improved the water quality benefits provided by two stormwater ponds adjacent to Martin Lake in Linwood Township. The project increased the size and depth of the ponds to the maximum extent practicable within the limited spaces available. The projects were a great success, and were recently highlighted in an outreach article titled, 'Water Quality Improvements Constructed for Coon and Martin Lakes'. They're worth mentioning again in order to highlight a critical piece of successful construction management that most people never see, the as-built survey.

As-built surveys, also commonly referred to as record drawings, provide formal documentation of exactly how a project was installed. They document the actual results of the construction project rather than the planned layout shown in the project design and are critical for project closeout.

As-built surveys ensure the project was built to meet the specifications in the original plan set. This allows the project engineer to confidently sign-off that the project was installed as per the plan. If any deviations from the original plan were approved during the construction process, the as-built survey will show the changes as they were installed and provide an opportunity to formally document those changes. Final payment to the contractor is also typically withheld until engineer sign-off on the as-built survey.

The as-built survey also provides a formal record that can be used to standardize how a project should be maintained over its lifespan. In the event of these stormwater ponds, accumulated sediment and debris should be periodically removed to achieve the original design depths in order to ensure the ponds continue to function at maximum efficacy.

Depending on the type and scale of a project, multiple as-built surveys may be completed throughout the construction process to confirm critical elevations and layouts are being met prior to approving advancement to the next construction step. They are typically shown as an overlay on the original plan sheet to allow a direct comparison and easy identification of any significant deviations from the original plan.

The 228th Place stormwater pond as-built (see plan sheet below) documented key elevations around the pond to ensure safe side slopes were achieved. It also documented the stabilized outlet and controlled overflow elevation to ensure neighboring properties were not at risk of flooding as a result of the project.

As-built surveys and the associated formal documentation they provide can sometimes be neglected because project installation went smoothly and according to plan, but they are a critical component to successful construction management and project closeout.

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ACD Partnering with City of Anoka for Mississippi Riverbank Stabilization

Approximately 1,500 linear feet of eroding riverbank within Mississippi River Community Park in Anoka will be stabilized in 2021. The project is currently in the early stages of design and focuses on a stretch of severely eroding riverbank that was documented in an erosion inventory completed by ACD.

Eroding river banks contribute to the Mississippi River's sediment and turbidity impairments through direct loading of sediment and nutrients that degrade overall water quality as well as aquatic and nearshore habitat. Stabilization of actively eroding riverbanks is one of the most cost-effective practices to improve water quality because 100% of the sediment reaches the waterway.

Stabilization techniques will include bioengineering with native vegetation and a rock armored bottom of slope to stabilize the riverbank. The project will reduce pollutants by 529 tons of sediment and 847 pounds of phosphorus annually. Other benefits include aquatic life diversity and abundance, and improved drinking water quality because the project site is immediately upstream of drinking water intakes for the Twin Cities.

This project will also showcase river stewardship and enhance public recreation. Mississippi River Community Park and adjacent Anoka-owned King's Island include 1.7 miles of Mississippi River trail, 0.78 miles of riverfront, 0.91 miles of oxbow channel, pedestrian access to the island, sporting fields, public duck and deer hunting, and a fishing dock. This project will make over ¼ mile of unsafe riverbank more accessible, stable, and fishable for users. By naturalizing the riparian zone, this project complements the Mississippi River Corridor Critical Area rules.

The project is funded by a Clean Water Fund grant, a Watershed Based Funding grant, and match from the City of Anoka. Watch for more updates from ACD and the City of Anoka as the project progresses.

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Mississippi Riverbank Stabilization Project Complete

The previously highlighted riverbank stabilization project on the Mississippi River in Ramsey has been completed. The residential property has 100 linear feet of riverbank that was nearly vertical and approximately 25' tall. Severe erosion was causing large portions of the bank to collapse and enter the river every year. The soil associated with those bank failures introduced significant volumes of sediment and nutrients into the river that contributed to water quality degradation. Stabilization of this severely eroding riverbank reduces annual sediment loading to the river by an estimated 224,000 lbs and total phosphorus loading by an estimated 112 lbs.

Project elements included clearing and grubbing of the few trees remaining on the steep slope, grading, riprap at the bottom of the slope, a reinforced soil slope (RSS) above the riprap to the top of the bank, native seed and plants, and erosion control blankets. The RSS consists of a honeycomb-like grid that is anchored to the slope and enables the finished slope to be steeper (e.g. 1.5 horizontal : 1 vertical), which maximizes the preservation of existing trees at the top of the slope.

Project funding is provided by a Clean Water Fund grant and landowner match.

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Mississippi Riverbank Stabilization Construction Underway

Stabilization of a riverbank on the Mississippi River in Ramsey has begun. The residential property has 100 linear feet of riverbank that is nearly vertical and approximately 25' tall. Severe erosion was causing large portions of the bank to collapse and enter the river every year. The soil associated with those bank failures introduced significant volumes of sediment and nutrients into the river that contribute to water quality degradation. Stabilization of this severely eroding riverbank will reduce annual sediment loading to the river by an estimated 224,000 lbs and total phosphorus loading by an estimated 112 lbs.

Project elements include clearing and grubbing of the few trees remaining on the steep slope, grading, riprap at the bottom of the slope, a reinforced soil slope (RSS) above the riprap to the top of the bank, native seed and plants, and erosion control blankets. The RSS consists of a honeycomb-like grid that is anchored to the slope and enables the finished slope to be steeper (e.g. 1.5 horizontal : 1 vertical), which maximizes the preservation of existing trees at the top of the slope.

The project is on schedule to be completed by early October. Project funding is provided by a Clean Water Fund grant and landowner match.
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Know Your Shoreline

If you live on water, whether it be a lake, river, creek, or stormwater pond, low water during the summer months can provide a great opportunity for you to conduct a quick inspection of your shoreline condition. The very bottom of your shoreline, where it meets the water, is called the toe and is the most critical part for stability.

Low water often exposes the toe of the slope and allows you to identify areas of concern. For example, you might observe undercutting, where the lowest portion of the bank has been scoured away by flowing water or wave action. When problems are caught early, the solutions are often much simpler and cheaper. Addressing erosion concerns early also helps prevent more severe bank failures down the road.

Another good time to inspect your bank is in the fall once leaves have fallen and before snowfall. You can inspect the upper portions of your bank for problems like rutting from concentrated overland flow over the top of the bank.

If you have any questions about your shoreline or think a site visit may be warranted, please contact ACD staff. We're here to help. 

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