Robert Williams, PE

805 Des Moines Drive

Windom MN 56101

 

October 18, 2007

 

Minnesota Department of Natural Resources

ATTN:  Commissioner Mark Holsten

500 Lafayette Road

St. Paul MN 55155-4040

 

RE:  Windom Island Park Dam

 

Dear Commissioner Holsten:

 

I am a resident of 805 Des Moines Drive in Windom, located along the Des Moines River.  I also hold degrees in Geo and Civil Engineering, Technology Management, and am a licensed civil engineer in Minnesota and Wisconsin.  I am a member of a group of residents directly involved in a city dam situation with the DNR in Windom.  I believe it is important that you be made aware of actions the DNR is actively undertaking in Windom that have a distinct potential to cause serious harm to public and private property as a consequence of the agency’s ongoing efforts to remove and/or destroy the Windom Island Park Dam.

 

I refer you to and ask you to read the enclosed Attachment, a copy of our dam group’s presentation to the Windom City Council on 9-18-2007 for a background of this dam situation from an affected homeowner’s and engineering perspective.

 

Since the presentation was made, the City has applied for a permit to restore the riverbank to at least achieve the former “status quo”.  Without actually turning down the permit outright, the DNR has placed numerous burdens upon the city that are impossible to meet in a timely manner, thus the DNR would achieve the stated and already budgeted for goal the DNR has of destroying the dam through a de facto denial of the permit application.

 

I note the following items in the October 9, 2007 DNR response by the DNR Area Hydrologist to the city permit application that are of special concern:

 

(DNR letter language is in Bold Italiacs.  My response follows in plain type.)

 

“1.  The dam exhibits the capacity for being a drowning machine (hydraulic roller) under certain flow levels.  Any significant maintenance project must incorporate a design to eliminate this threat to public safety and bring the dam up to current safety standards.”

 

·  There have been no deaths attributable to the dam.  In fact there is a demonstrably much greater risk to public safety due to hunting, which the DNR actively supports.

·  The proposed riverbank restoration work is arguably not a significant maintenance project to the dam itself; preventing any maintenance work on a public works structure is not responsible stewardship of public assets.

·  I understand City leadership as well as our Windom Dam Group members would nonetheless support a riprap retrofit as described in our city council presentation and a DNR video presentation.  There is no demonstrated urgency to tie a retrofit to the immediate repair of the riverbank itself.

 

 

 

“2.  When any dam in the State of Minnesota has washed out in the past 10 to 15 years, DNR Dam Safety has required the applicant to meet the same standards as a new dam construction project (Rule 6115.0410).  Since the Des Moines River currently bypasses the dam, and thus functions more like a river without a dam, the city must meet the guidelines of Rule.”

 

I note that Rule 6115.0410 Subparagraph 2 actually states:

  “Subp. 2.  Permit application.  A separate application,

 including a preliminary report for each new dam or each dam

 proposed to be enlarged, shall be filed with the commissioner

 upon forms provided by the commissioner which shall contain the

 following:”

 

It appears there is absolutely no basis in rule or law for this significant assertion of regulatory authority claimed by the DNR.  It also appears this claim of authority would have applied if at all to failures of the dam itself.  The Windom dam structure is fully intact.  The failure in question is instead along the riverbank.

 

 

 

“3.  The proposed project is not presented as an adequate long-term solution.  The dam has a history of washing out around this abutment and will likely wash out again….”

 

The City did present the proposal as only an interim measure.  If the former repair was a “temporary measure” as described then it is noted that the “temporary” repair lasted more than 20 years, which would be a good value on what was likely, a modest investment of public funds.  It would still be in effect today if anyone had bothered to correct the long term downcutting that was the mode of the riverbank failure in any sort of a timely manner this past winter or spring when the problem was minor.  A more robust repair that takes into account the overtopping concern would in fact be a permanent fix by any reasonable engineering standard.   

 

 

 

“4.  It is not good engineering practice to allow water to flow over the abutment of a dam.  The abutments should be built high enough to keep flow in the channel and flowing over the weir (spillway), not the abutments.  It appears that there is not to be enough weir length to pass flood flows (i.e. the spillway is too narrow).  Dam Safety inspection records show water was flowing over the left abutment in 1995, 1999, and in 2005.

 

It is fully agreed that flood waters flowing over an inadequately protected riverbank abutment is not desirable.  For this situation it would be appropriate to have a more stable surface on the abutment than loose rock fill.  However, major flood flows typically inundate the entire Island Park area, essentially submerging the entire dam as the flow tends to cut across the river meander in which the dam is located.  For this reason, widening the dam would have no appreciable effect.  Removing the dam would have the harmful effect of increasing water velocity significantly in a relatively narrow channel area, thus increasing erosive effects in an area with a large steep slope with public streets and houses.

 

The beneficial effects of a low head dam spread the flow across the width of the weir as noted in our 9-18-2007 City Council presentation (as per discussion from North Dakota State University).  This serves to minimize potentially catastrophic erosive effects in a relatively narrow river channel that would be present with an uncontrolled meandering river in the Island Park area.

 

 

 

“5.  The poor condition of the right (west) abutment must be addressed as well.”

 

It is agreed that scarifying and shotcreting of abutment concrete would be warranted as part of maintenance work.  However this issue is completely unrelated to the failed riverbank.  The current actions of the DNR hindering the bank repair may lead to the undermining and destruction of the dam which would make the abutment repair moot.

 

 

 

“Additional guidance is notable in 6115.0250 Subpart 1A Effect on environment and mitigation.  “The DNR commissioner may not issue a permit that causes pollution, impairment, or destruction of the air, water, land, or other natural resources so long as there is a feasible and prudent alternative consistent with the reasonable requirements of the public health, safety, and welfare.

 

The general beneficial effects of low head dams in urban settings has been demonstrated by North Dakota State University Research.  Visual evidence clearly shows that the Des Moines River is a classic meandering river.  It will meander and therefore adversely affect public and private property if not effectively controlled.  There is no demonstrated alternative that negates this effect as well as efficiently as a low head dam.  One of the DNR proposals was to create a rock dam which is no substitute for a real, existing, and more robust dam. 

 

 

 

It is also noted that the DNR letter on page 3 contains a section citing Rule 6115.0215:

“Subpart 3” – Prohibited work.  Public waters alteration, protection, or restoration work is prohibited when the work:…”

Various items A thru G are then listed in the letter.  The DNR is apparently using this portion of the letter to imply the City may not be allowed to restore the “status quo” ponded environment even if all the other issues raised by the DNR are addressed.

 

The DNR letter however omitted Item “H” from the Rule which states the following:

 

“Subpart 3 – Prohibited work.  Public waters alteration, protection, or restoration work is prohibited when the work:…”

“H.  will adversely impact public infrastructure, particularly roads and drainage systems.”

 

This language would have clear application to the Island Park area and potentially the Highway 62 bridge as well.  An uncontrolled meandering river will tend to cut directly across Island Park and tend to create an oxbow lake in the existing dam area.  Again, as noted by others, low head dams act to stabilize shoreline situations in their pool area.

 

It is also noted the sanitary sewer system main line for the Rolling Green neighborhood is in the river immediately upstream of the Highway 62 bridge which is itself immediately upstream of the Island Park dam.  The Rolling Green neighborhood contains many residences, a nursing home, senior apartments, and an assisted living facility.  One of the two watermains serving this entire neighborhood is immediately downstream of the bridge, closer even yet to the dam.

 

The dam serves to stabilize the riverbed and serves to insulate these pipes from freezing and protect these lines from frost heaving effects.  Forcing the removal of the dam, which is the clear and present agenda of the DNR, may leave this critical public infrastructure susceptible to scour, heaving, and freezing. 

 

 

 

In conclusion, it is evident the DNR is imposing potentially serious increased risks to public and private property if the agency continues to prevent the city from restoring the riverbank in a timely manner.  Not granting the city a permit to restore the riverbank with reasonable conditions is contrary to the expected position of the DNR set forth in writing to me by 2 DNR staff members.  It also places politically driven and very contestable environmental considerations well ahead of sound engineering judgments and evaluations that are a vital component of such major decisions.

 

Our Island Park Dam group members urge the DNR to seriously reconsider their position in this matter.  We suggest the DNR seriously consider that existing low head dams can and do play a useful role in developed city environments such as found in Windom.  As implied in our City Council presentation there are many areas in which the City and DNR can and should work together to improve the environment, as long as the continuing protection of public and private property is a key consideration in the decision making process.    

 

Sincerely,

 

 

 

Robert Williams, PE

robertlaura@windomnet.com

 

Cc:   Senator Jim Vickerman with Attachment

        Representative Rod Hamilton with Attachment

        Office of the Governor with Attachment

        Windom City Mayor Tom Riordan w/o Attachment

        Windom City Administrator Steve Nasby w/o Attachment

        DNR Area Hydrologist with Attachment