3. Citizen Group Power Point 6-24-15 City on LHL 1Log House Landing
Design Alternatives
A presentation to the
Scandia City Council
July 1, 2015
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Why Are We Here?
•The Watershed asked the City to “fix” the Log House Landing (LHL) Road to address
concerns over on-going erosion issues impacting Gilbertson’s Creek and the Saint Croix
River
•The City established an Advisory Committee to study the issue and make
recommendations
•The recommendations were approved by the City Council, but it was later determined
DNR/MnDot Grant funds could not be used for the recommended design
•The City Council granted a request from the Chair of the Advisory Committee to research
alternative road surfaces and present viable alternatives
•The City Council asked the Watershed to define how big a solution is needed to “fix” the
erosion issues
•The Watershed President asked Steve Kronmiller to take the lead in developing a
recommendation for the Managers to review and pass on to the City Council
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Watershed Concerns
•Nutrient Loading –While initially raised as a concern, the Watershed has
since determined phosphorous loading is NOT a concern at this site.
•Sediment Loading –The most recently revised modeling estimates between
4 and 10 tons of sediment erodes from the 13 -foot gravel road surface
annually. This is far less than the 25 tons originally estimated.
•Environmental Impact -Any solution to the problem needs to minimize the
environmental impacts to the trees, vegetation, the creek, and the river.
•Cost -The cost to address the erosion needs to be in line with the size of the
problem.
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Sediment Loading Observations
GILBERTSON CREEK
Primary source point near culvert
•Culvert diverted water and gravel toward creek. Now plugged.
•Breach/low point in the natural berm allows run-off at culvert location.
•Road had sloped to the south at culvert location directing run -off toward the
creek. Recent grading to the north has diverted most of the water and fines
away from the creek.
•2013 sedimentation tests were in line with other creeks in the area
SAINT CROIX RIVER
Two primary source points –boat ramp and northeast landing edge
•Landing is sloped toward the river at both locations
•Fines from sedimentation have settled on landing, turning it into what has
become a large shallow holding area.
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Sediment Loading Suggested Solutions
GILBERTSON CREEK
•Additional regrading to achieve a 4% slope away from creek
•Berm restoration
SAINT CROIX RIVER
•Install concrete planks on ramp (approved by City and Watershed)
•Crown landing to divert water away from boat launch ramp
•Grade landing away form river bank at 4% slope
•Establish two shallow ponds as BMPs to allow for infiltration, evaporation
and removal of sediment
•Install natural barrier at bank to prevent snowplows from damaging
neighboring soft surfaces
•Restore river bank
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Road Designs and Surfaces
•Surface
•Width
•BMPs
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Alternative Ways to Implement
Solutions
MN-DOT Approved Surfaces Considered
1.Gravel
2.Bound-Aggregate
Gravel mixture using a specific gradation with a specific amount of fines and
clay to act as a binding agent that can significantly reduce erosion.
3.Bound-Aggregate with Chloride
•Magnesium or Calcium Chloride is mixed into the surface during
installation to create a tighter road surface.
•This does NOT create the issues that “road salt” does. The chlorides
used are similar but it is not sprayed on the surface and does not run
off like road salt.
4.Asphalt
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Option One: Existing Road Surface
Re -engineered
ACTIONS
•Re-grade the road to the north and landing to north and west to provide 4% in-slope to keep runoff
away from Gilbertson Creek and the Saint Croix River
•Use rocks from existing road to create small 1-1 ½ ‘ rock ditch on north side of lower road (starting at
Quint) to slow water
•Install two shallow sedimentation ponds (half way down the road and by the landing) to allow for
infiltration, evaporation and trap sedimentation before reaching the Saint Croix River
•Establish a road maintenance and storm water management plan
•Restore the Saint Croix River and Gilbertson Creek banks
RESULTS
•Will reduce erosion and will improve road performance. Sediment will collect in ponds and can be
removed as needed
•Minimal construction that significantly limits environmental impact
•No new materials added to the road
•Provides 14 Turnout Areas for passing or Emergency Vehicle Parking: 8 Turnouts on South Side of
Road and 6 Turnouts on North Side of Road
•Maintains the rural and historic character of the area
•Maintains protective tree canopy
•Supports the size and type of watercraft appropriate for this section of the river
•Compliant with the Scandia Comprehensive Plan
•Lowest Relative Cost = $
NOTE: Items in read note differences between Option One and Option Two
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Narrow rock
Channel
14 Turnout Areas for
passing or ER Vehicle
Parking: 8 Turnouts on
South Side of Road and
6 Turnouts on North
Side of Road
Existing Parking Areas
(North Side of Road)
Existing Road
Width and Surface
Turnout surface remains natural
vegetation
Option Two: Bound Aggregate Surface
Re -engineered
ACTIONS
•Re-grade the road to the north and landing to north and west to provide 4% in-slope to keep runoff away
from Gilbertson Creek and the Saint Croix River
•Add 6” bound aggregate surface
•Consider adding chlorides to further stabilize surface (optional)
•Install 3’-4’ wide rock ditch on the north side of the lower road (starting at Quint) to slow water
•Install two shallow sedimentation ponds (half way down the road and by the landing) to allow for
infiltration, evaporation and trap sedimentation before reaching the Saint Croix River
•Establish a road maintenance and storm water management plan
•Restore the Saint Croix River and Gilbertson Creek banks
RESULTS
•Will significantly reduce erosion and improve road performance.
•Maintenance of ditch BMPs will likely be 10+ years schedule for clean out
•Minimal construction that significantly limits environmental impact
•Provides 14 Turnout Areas for passing or Emergency Vehicle Parking: 8 Turnouts on South Side of Road and
6 Turnouts on North Side of Road
•Maintains the rural and historic character of the area
•Maintains protective tree canopy
•Supports the size and type of watercraft appropriate for this section of the river
•Compliant with the Scandia Comprehensive Plan
•Relative Cost = $$
NOTES: * This alternative was not presented to the LHL Advisory Committee
* Items in read note differences between Option One and Option Two
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4’ Rock Channel
14 Turnout Areas for
passing or ER Vehicle
Parking: 8 Turnouts on
South Side of Road and
6 Turnouts on North
Side of RoadExisting Parking Areas
(North Side of Road)
Existing Road Width Bound
Aggregate Surface
Turnout surface remains
natural vegetation
Option Three: Hybrid Design
Combine features from Option One and Option Two:
•Road Section –Option One: Existing Road Surface
•Landing Section –Option Two: Bound Aggregate Surface
Relative Cost = Not estimated ($ -$$)
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Hybrid Design
DNR provides planks to be installed at the
boat launch.
Install a Bound Aggregate surface on the
landing area and on the launch down to the
DNR planks
Install a natural barrier around the landing
area to prevent snowplows from damaging
neighboring soft surfaces
Crown the landing surface to shed runoff
away from the boat launch and away from
the St Croix River
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⏎
Asphalt Alternatives
Common Advantages:
•Address the erosion issue
Common Disadvantages:
•Concern about freeze-thaw frost and cobble ejections
•Curb/gutter eliminates all natural turnout areas for passing and or Emergency Vehicle Parking
•Does not maintain the rural and historic character of the area
•Conflicts with National Park Service and St. Croix River Association requests to maintain the rural character
of the area
•Conflicts with overwhelming citizen expressed opinions-55+ letters to Council and Planning Commission,
550+ petition signers
13-foot Design with Asphalt Surface –LHL Advisory Committee Approved
•Narrow design limits environmental impact
•DNR/MnDOT Grant Funds cannot be used
•Relative Cost = $$$
20-foot Design with Asphalt Surface
•Complies with NFPA and ICC Standards
•Option was rejected by the Advisory Committee as too impactful and not in keeping with Comprehensive
Plan
•Wider option increases environmental impacts with significant tree removal and canopy reduction–would
increase the amount of storm water reaching the road
•It is believed a variance could be granted to allow use of DNR/MnDOT Grant Funds
•Relative Cost = $$$$
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20’ with 8’ Parking Road
Width. Asphalt Surface
Two Parking Areas
(South Side of Road)22 trees and much
vegetation removed
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“To Pave or Not to Pave” Published on Jan 7, 2013
This professionally developed DVD (funded by the Local Road Research Board -MnDOT) was
developed to assist local agencies to understand and communicate the benefits of
pavement management.
Estimated Installation Cost
Comparison
Options Costs
Option One: Existing Surface
Reengineered
$102,134
Option Two: Bound Aggregate Surface
(Higher amount includes additional chloride
stabilization)
$148,664
$161,864
Option Three:Hybrid
(Road -Option One/Landing-Option Two)
not
estimated
13’ Asphalt $304,074
20’ Asphalt $370,908
Original Grant Plan (2013 cost estimate)$400,000
Road Maintenance Cost Comparison
•Gravel to Asphalt
•MNDOT’S Local Road Research Board indicates that maintenance costs
for a low volume gravel road are 30% less costly per mile than asphalt.
•Low volume road is 0-49 ADT(Average Daily Trips )
•Log House Landing road 2015 informal parked car sampling ADT =3.8 (May
& June including the fishing opener weekend)
•Bound Aggregate to Asphalt
•Steve Monlux estimates bound aggregate should be more than 50% less
costly per mile than asphalt when traffic counts are low
•Bound Aggregate to Gravel
•Bruce Hashbargen, Engineer for Beltrami County MN with 350 miles of
gravel roads including roads with 11% grade states that bound
aggregate significantly reduces maintenance over gravel
•Gravel Maintenance Events = 2X per month and after significant rain
events
•Bound Aggregate Maintenance Events = 2X per year
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BMP Maintenance
•Current estimates of 5 tons of gravel is a very small amount –a small pile of dirt
•Re-engineering existing surface should achieve 70% reduction in suspended solids
•With bound aggregate, the reduction is 90%
•Correct grading (4% in slope) will significantly reduce the drainage path length, which
lowers velocity and reduces erosion
•Using bound aggregate will reduce erosion from road by 75% -more with chlorides
(Ken Skorseth)
•Experience with bound aggregate suggests 10 year intervals between ditch cleanouts
(Ken Skorseth)
•Effective sediment basins should achieve a 70% removal rate for suspended solids (U.S.
EPA, 1993)
•Local estimate for cleaning ditches is $1,000 per maintenance event
•Local estimate for cleaning settlement ponds is $1,500 per maintenance event
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