The first phase in the City of Riverdale’s long-range project of re-building and improving the stormwater drainage way off of Fieldcrest Road has been complete. The sanitary sewer line in the ravine has been stabilized and the City is now planning for the next phase of the project.
Work is expected to begin soon on changing the path of the stream bed off of Fieldcrest Road in order to arrest the continued scoring and erosion under the City’s sanitary sewer line running between Deerbrook and the Woods Estates of Riverdale developments. The erosion problem has been a lingering one and was significantly impacted last year by the record rains and resulting ground saturation.
McClintock Trucking & Excavating has been hired by the City to change the course of the stream’s bed and re-build the eroded bank to preserve the sanitary sewer line. They will also be adding about 30 yards of stone (“rip rap”) to help diffuse water flowing through the stormwater outlet at the end of Fieldcrest Road.
“This is the first phase of a much larger project,” explained Mayor Mike Bawden. “We’ve been working with the City’s engineering consultancy, MSA Professional Services, to assess the problem and develop a long-term solution that will allow us to handle the excessive stormwater generated off of the Scott Community College parking lots and homes on Manor and Circle Drives. Right now, that water is collected under Fieldcrest Road and flows down the drainage way.”
The drainage way, he explained, was never intended to be a constantly-flowing creek and in seasons where we see enormous amounts of rainfall, significant erosion can result.
“The immediate concern addressed with the current project, is to shore up the bank underneath the City’s sanitary sewer line – which would cost significantly more to repair or replace should the bank completely wash out from underneath it,” Mayor Bawden explained. “In the longer term, we want to find a solution that is both aesthetically pleasing – preserving as much natural beauty as we can – and effective at handling large amounts of water we’re bound to see as severe weather events continue to be more commonplace.”
For on-going updates on this project, check out the Fieldcrest Draining Stabilization Project page on this website.
MSA prepared contract documents for McClintock Trucking and Excavating to execute. These have been executed and returned to the City.
When the City executes these documents, McClintock Trucking and Excavating is ready to begin work on this project. MSA suggests a meeting with McClintock prior to equipment arriving on the project site. MSA also suggest the City include notice of this work in the City newsletter.
MSA has reviewed the previous MSA Scott Community College detention basin analysis performed in 2009. This initial work was completed because of the frequent flooding of this pond was causing damage to homes that backed up to this pond. That analysis indicated the pond was significantly undersized and inappropriately designed.At that time (2009) the City did not have storm water detention standards so there was not a legal way for force Scott Community College to provide larger storage volumes in their pond. MSA suggested several solutions. The solution accepted by the City of Riverdale was to provide increased pipe outlet sizes at the basin reduce the occurrences basin flooding.
In addition, MSA evaluated the existing emergency overflow.
It is our opinion there are several obstructions in the overflow that will prevent adequate discharge when there is a need. However, MSA is not aware if there are limitations on what surface features are allowed by the Home Owner at this location.
MSA is still evaluating this pond and downstream discharge mitigation options.
MSA Professional Services, the City’s engineering consultancy, informed the Council that it had met with McClintock Trucking and Excavating to walk the project site and discuss it in more detail. McClintock offered the suggestion of relocateing the creek/drainage way as the best possible solution.
Because the creek/drainage way is not recognized by the Iowa DNR as a waterway, and per the US Fish & Wildlife Service, the area is not a recognized wetland, the requirements that would have to be met to accomplish this task are minimal.
MSA agreed this solution would maintain the width of the walking trail and would provide better assurance of the stability of the adjacent sanitary sewer. Therefore, MSA requested that McClintock Trucking & Excavating provide a proposal for the work, as discussed. That proposal was submitted to the Mayor, Administrator and Council Member Heddlesten (a civil engineer).
The estimated cost of the project from McClintock Trucking and Excavating was $19,840, well under the $43,000 limit requiring a formal construction bidding process. The City Council took MSA’s recommendation to accept the proposal from McClintock and passed Resolution 2020-18, directing City Staff (MSA) to proceed with getting a formal proposal documentation in order for review and acceptance at the next Council meeting (on March 1o).
Phase II Planning Underway
As for the second phase of this project, MSA is currently investigating the design of the Scott Community College detention basin. MSA will provide mroe specificity on this after they have completed their investigation.
MSA Professional Services, the City’s engineering consultancy, informed the Council that it is working on improving the potentially selected first phase of stabilizing the bank of the Fieldcrest drainage creek wehre future score erosion may conflict wiht the existing santiary sewer. MSA further states they are seeking improvements on constructability and a reduction in project cost.
MSA created a model of the existing drainage for Scott Community College, including the existing detention basin. MSA modified that model to include the Manor Drive Residential Subdivision. Furthermore, MSA modified the model to also include tributary portions of Woods Estates. In a future update or project report, MSA is expected to summarize their findings of existing conditions.
The Mayor has requested that update be given no later than the March 10 City Council meeting.
At a meeting with the City’s engineering firm, MSA Professional Services, the Mayor asked the firm to continue with developing a more complete project estimate for the first phase of this project and to make plans to begin scoping out the second phase of this project as soon as the weather looked like it would cooperate.
The City’s engineering firm, MSA Professional Services, informed the City Council that it has prepared a recommended “first step” towards stabilizing the drainage way from Fieldcrest. The document provided to the City Council included pictures of the problem area and budgeted cost levels.
The Council was presented MSA’s letter and supporting documentation and encouraged to review it before the next Council Meeting so it could be discussed in more detail.
Following a meeting with the City Administrator and Mayor, MSA Professional Services was asked to prepare a recommendation to the City Council that provided a more detailed explanation of the plan and costs related to the first phase of this plan.
The City’s engineering firm, MSA Professional Services, advised that they have walked the area of concern and identified two alternative locations for the first phase of the stabilization project. MSA advises that they are working on budget costs for these projects and will assist the City in deciding between the two alternates.
The City’s engineering firm, MSA Professional Services, reported the following:
• MSA has obtained LIDAR data, determined approximate watershed limits, and determiend approximate design flow rates. MSA still needs to determine a revetment stone size.
• MSA recommends a meeting with the Contractor (Seth Woods) to determine how best to access the creek and the best method of localized stabilization. (The Mayor had suggested that Mr. Woods was amenable to assisting the City in getting rip-rap into the drainage way and might be able to provide access to the site and equipment to move material, if needed. No firm arrangements have been made at this time.)
• MSA will provide Administrator Kotter with an exhibit showing the drainage way of concerna swell as two alternative recommendations for an initial placement of revetment stone. MSA cautioned that the stone is of significant size and that if the decision is made to use smaller stones, gabion mattersses or baskets could be utilized.
• The first phase of the porjec tis subject to budget limitations that have not been set (at this time). It is also subject to access considerations that have not yet been discussed or determined.
The City’s engineering firm, MSA Professional Services, reports that it has determined design flow rates and is now reviewing possible revetment stone locations and configurations. A meeting with the City and Mr. Woods is probably necessary to discuss possible access and locations for revetment stone installation.
The City’s engineering firm, MSA Professional Services, reported to the City Council that it has begun conceptual modeling of the watershed.
The City’s engineering firm, MSA Professional Services, presented the City with a professional services agreement in the estimated amount of $14,000 to develop a two-phase approach to dealing with erosion concerns related to the storm water drainage way running off of Fieldcrest Road.
A copy of Resolution 2019-47, complete with a copy of the proposal from MSA can be found here.
MSA Professional Services, the City’s engineer, reivewed the request made to furnish a proposed agreement to address the scour erosion occuring at the pipe discharge from Fieldcrest Road. According to MSA’s representative, Chris Cooper, they are currently working on this proposed agreement.
MSA had discussed modifying their approach to this agreement with the Mayor and the Admnistrator. Their first approach was two-phase. The first phase was to identify a point to harden the channel so that further scour to the channel is eliminated at that point. The second phase was to identify other points to harden the channel to eliminate scour erosion, stabilize the banks to protect the sanitary sewer and to reduce channel slope.
MSA’s new approach is also two-phased. The first phase will be to identify a point to harden the channel so that further scour erosion is eliminated at that point. The second phase will be to identify additional storm water detention opportunities to reduce peak flows as much as possible. These opportunities in clude modifying the Scott Community College detention basins and creating ad etention basin for the Manor Drive subdivision.
The intent of MSA’s modified approach is to minimize both project cost as well as disturbance to the wooded, City-owned lot. It remains a goal to protect the City’s sanitary sewer and minimizing further scour erosion downstream of the Manor Drive Subdivision.
The City’s engineering firm, MSA Professional Services, informed the City Council that it intended to provide a proposal on this project by October 15 so it could be discussed at the October 22 meeting.
Scope of Work:
MSA Professional Services is currently working on a definitive scope of work based on their analysis of the scour erosion occurring at the pipe discharge from Fieldcrest Road and the creek bed that is intended to carry the water away and to Duck Creek. The problem exists in both Bettendorf and Riverdale and will probably require the cities to work together to address the situation.
The first phase of this project will address immediate erosion issues found near the location of the City’s sewer lines running through the drainage way. It is hoped a solution will be put in place in 2020.
The second, more significant phase of this project will require coordination with other governmental bodies. It is hoped an outline of the required action and estimated cost can be determined in 2020 for action in later years. The cost and timeline, at this point, are not reliably predicted.
$14,000 – Consulting Engineering/Plan Development
$20,000 – Phase I (2020)
Project Bid Date:
Project Start Date:
Phase I: 2020
Phase II: TBD
Project Completion Date:
Phase I: 2020
Phase II: TBD