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http://www.macon-bibb.com/SWC/SWCC.htm
Public page - http://www.macon-bibb.com/SWC
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https://gaswcc.georgia.gov/watershed-dams
Tobesofkee Dam
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David P. Fortson, P.E.
Bibb County Engineer "Fortson, David" <DFortson@maconbibb.us> 478-621-6660 478-361-9682 (C) 478-621-6666 (FAX) http://www.maconbibb.us/engineering David, The Ocmulgee River S&Water group has asked me to give an update to the Tobesofkee Dam at our next months meeting. Has anything happened since we visited the dam site last July? Thank-you, - Lindsay PS - The "Final Report" in 2018 by the engineering firm Mead&Hunt mentions the existing balance arm system "has historically proven to be unreliable". They also imply the "ongoing costs for maintenance of the balance arm system" might be very expensive. . Some thoughts by a non-engineer: Doesn't the balance arm counterweight allows for a smaller (cheaper) motor to operate and lift the spillway gates. What needs to be maintained on a simple teeter-totter, see-saw lever arm? Paint? Hydraulic motor? Using the energy of falling water to lift the gates? Or simply fill (add water to) the counterweights to lift the gates? Or, hang fill-able barrels from the counterweight.. hang lower than the lake pool level...fill with gravity powered hoses... Mead&Hunt Report is posted online - http://www.macon-bibb.com/SWC/Tobesofkee-Dam_Final-Report_engineereing.pdf . "Section 2 Alternatives Analysis B. Alternative No. 2 "..the existing balance arm system, which has historically proven to be unreliable. For this reason, MBC may find it difficult to obtain NRCS approval of Alternative No. 1. Furthermore, our budgetary cost estimate does not include ongoing costs for maintenance of the balance arm system, which would be required for continued reliable operation. Budgetary cost estimates for each alternative are provided in Appendix B.. " |
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Lindsay, I apologize that we missed each
other on the phone a few times. I actually
retired from NRCS at the end of last year and have
been working just 2 days a week. I have attached
the instructions for the Level 2 USDA Authentication
access which is needed for DamWatch. Of the 357 NRCS structures in
Georgia, this structure has a unique gate system as
opposed to a typical principle and auxiliary
spillway. I really don’t have any specific
information as to the history of issues with the
gate. Also, any modifications to the
structure should be reviewed and concurred by
NRCS. This will ensure that the structure
remains eligible for any federal funding in the
future. If you have any questions, or need any
additional information, let me know. George Skovran |
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From: "Mimbs, Jessica"
<jessica.mimbs@gaswcc.ga.gov> To: Holliday Dental <teeth@mindspring.com> CC: Katie Sponberger <katie@gacd.us>, Timothy J Allen <brnt@ymail.com>, Subject: RE: Tobesofkee Dam in Bibb County - proposed modifications Date: Fri, 12 Apr 2019 18:45:41 +0000 Good Afternoon Lindsay,
It was nice speaking with you this afternoon. Thank
you for sending me the next District Meeting
information. I went ahead and put it on my calendar and
I plan on attending.
Also, thank you for sending all the information
regarding the gate and the history of the gate issues.
Let me look through all of this over the next few weeks
and familiarize myself with everything, because I can
definitely help you all with the process of what needs
to be fixed and the steps to get it technically reviewed
by NRCS, and potentially some of the funding.
Please feel free to reach out with any questions.
Thank you,
Jessica Mimbs
Rural Water Resources Program Manager
Georgia Soil and Water Conservation Commission
4310 Lexington Road
Athens, GA 30605
706.552.4470 Office
706.286.2858 Mobile
-----Original Message-----
From: Holliday Dental [mailto:teeth@mindspring.com]
Sent: Friday, April 12, 2019 2:38 PM
To: Mimbs, Jessica
<jessica.mimbs@gaswcc.ga.gov>
Cc: Katie Sponberger <katie@gacd.us>;
teeth@mindspring.com; Timothy J Allen
<brnt@ymail.com>; Marcus.Griffin@ga.usda.gov;
George.Skovran@ga.usda.gov
Subject: Tobesofkee Dam in Bibb County - proposed
modifications
Jessica,
The next Ocmulgee SWC District meeting will be on
Thursday, June 6, 2019 at the Ag-Georgia Farm Credit
Bldg., 468 Perry Parkway, Perry, GA 31069 at 6:00pm.
If I understand the source of the Tobesofkee Dam
problem, and I doubt that I do, it is this:
The lateral seals on the two gates are too
tight/sticky. This problem maybe due to the
original construction being out of specified
tolerances? The tight seals don't allow for smooth
operation of the gates using the floatation
counter-weights. The gates "jump" when enough
force is applied (by the float-counter-weights) to
break the friction resistance of the gate seals.
In order to operate the gates with greater control,
over the years, an electric hoist system to operate the
gates has been created. This electric hoist is assisted
by the original floatation counter-weight system.
The lift mechanism has had various problems over the
years:
...
About a year ago one of the (4) electric-hoist cables
broke. Photo:
The broken cable has been replaced, but this event
precipitated the current plan(s) to modify the gate-lift
system.
Bibb County hired the engineering firm of
Mead&Hunt to develop preliminary plans.
Here is their Mead&Hunt "Gate Hoist Replacement
Study" dated Feb 2018:
Mead&Hunt do not address the sticky gate seals
(if that is the underlying problem), rather they plan
for a stronger electric hoist system.
Mead&Hunt have detailed an estimate on sheet 22
of 25. The funds Bibb County would like to apply
for are the $85,000 design and $34,500 design
contingency funding, for a total of $119,500 to do the
design of the system. After that, Bibb would have
a better idea of the construction funding required and
the engineering inspection funding required.
Mead&Hunt have a $522K construction contingency in
the estimate, so there are a lot of unknowns until the
design is fleshed out.
Here is a link to a summary of the NRCS inspection of
the Dam dated 1-29-2018:
- Lindsay
Other images of dam:
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as "approved by Fenley Ryther, Jr." circa 1964.
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Back
Side East Gate.jpg 
Counterweight on Rocker Arms.jpg 
Front
of Dam from RipRap.jpg 
Gear
System Looking Downstream.jpg 
Gear
System Side View.jpg 
