200 YARDS OF BOG ROAD

[PWS]

I'll probably end up paying to improve a gravel road which passes over parts of a bog in Northern Wisconsin. The road has been there for over 60 years and two spots sink into water table. Roadway is 15 feet wide. Low spots have been filled with stone several times. The stone sinks in about 5 years.
Is Geotextile fabric an option here? Is there a way to use it over the sink holes? Holes sink to 14 inches below water table.
Town refuses to pay for maintenance.
Phil

 

[Focht3]

If the sinking area is 200 yards by 15 feet, then the geotextile won't do much good - that's too large of an area to bridge. If the problem is spotty, though, a geotextile can help.

Is the road on private land, or is it a public right-of-way? How much gravel would it take to raise the wearing surface above the water?



Please see FAQ731-376 by [blue]VPL[/blue] for tips on how to make the best use of Eng-Tips Fora.

 

[SirAl]

This may not be an easy fix. You should consider having a geotechnical engineer assess the problem. A few exploratory holes may be in order. Organic deposits, if that is the culprit, can compress as well as spread laterally under the influence of an applied embankment loading.

 

[PWS]

Focht3
The low water spots are about 6 yards long. This is an easement road over government land. I'm currently negotiating a new easement and would like the Town to kick in some of the cost. The spots needs up to 24 inches of gravel and the entire 200 yards needs an added grade of 8 inches to keep it above water.

SirAl
The actual open water of the lake varies from 100 to 500 yards to one side of this roadway. There are floating bogs at various points around this 270 acre lake. I know from the road foreman that some bog spots are as deep as 40 feet. What about wooden piles jetted into the low spots before applying the geotech material? If there's anything we got for building materials up here its tree trunks.

 

[VAD]

Looks like you are getting slow lateral displacement of the roadway into the lake. In such cases a berm would have been appropriate during the initial design. At this stage that would be some what expensive.

Some thoughts. If the fill sinks every five years consider using a light weight fill. With tree trunks you can construct a courduroy road (raft type construction) which was used initially to float roads on muskeg. This concept is still used on occasions and may be a cheaper alternate. Geotextile can be used over timber before placing the fill
This problem needs some innovation as costs can be high.

Several solutions are possible.

What type of vehicles in terms of weight and axles, traverse this roadway?

Are there any equalizer culverts in place?

You could also think of excavating some of the heavy fill and do a replacement with lighter weight material. This really depends on site assessment.

Thats all for now. Interesting problem that tests the geotech engineer in relation to cheap and workable solutions

 

[PWS]

Vad,
The roadway needs only to support passenger cars and an occassional electric company truck to repair downed power lines. The electric company trucks are no heavier than 6 ton ten wheelers.
"Equalizer culverts" sounds like a useable addition to reduce excessive softening of roadway by the periodic high lake level.
Would tree trunks be better used as corduroy floatation or as piles to reach stable soil at bottom of bog assuming stable soil was reachable?
Original road footprint came from 1890's narrow gauge railroad. I assume bog spots were originally filled by railroad Co. Logging was the original purpose.

 

[KRSServices]

You raised two issues with regard to the road, I will deal with the right of way firstly, and then some ideas regarding the road.

Who are the parties in the right of way (easement) agreement? If the agreement covenants that a road be constructed, there is usually accompanying clauses specifying maintenance. From your post, it appears that the agreement is between yourself(?) and the power company(?) and the State (government lands?). What I am not clear on is the passenger traffic and how they relate to the easment agreement. Is the passenger traffic something that has happened since the agreement date?

Where I am going with these questions is the fact that the agreement may make provision for maintenance or provide you with a termination clause somewhere.

As to the road, there are a number of cost effective solutions, however, burying the trees is not one I would recommend. I've maintained and constructed county roads for over 15 years, and I have a few ideas.

You can call me @ (780)573-1884 if you want to go over some of the easement or road issues.

KRS Services

http://www.krs-services.com

 

[VAD]

PWS:

Thanks for the information. I am not in a position to offer any definitive solutions to this type of problem as my experience has taught me that everyone may be different. For piles, tops of piles will have to be tied together and across the road. I presume that you are thinking on having piles on both sides of the roadway. This venture would benefit from a couple of holes drilled in the roadway to depth. Culverts placed side by side can be used as well to reduce weight, if this is a reason.

Other thoughts are possible erosion if road is in a bend. I have seen logs tied in the lake to dissipate wave action especially in windy areas. Again site assessment would be important to determine whether erosion is a possible problem

It appears that KRSS has some ideas as well. Please let us know what solutions are offerred, so that we can be enlightenment on what others have used and what works.

 

[layfieldman]

To your original question about geofabrics, they will not help support the weight of the road as there is nothing that they tie into. As stated in most texts for geosynthetics design that if the subgrade will not support the embankment a geotextile will not prevent this. Geotextiles will help only with lateral slumping of the embankment and will sometimes help cover sinkholes, must be carefully designed with very high strength polyester or nylon woven geotextiles.

 

[johnhan76]

I have had an engineer explain geotextile use in roads by saying it distributes a point load (tires) over a larger area of the subgrade (similar to a footing). This is contrary to what I am hearing on this board which is you need something to tie into.

 

[KRSServices]

I do have some ideas, but firstly, I need to know what soils are under the roadway and whats avaiable for borrow. Secondly, where are the road grade and ditch elevations in relation to the water table? Thirdly, is this a lake or a marshland? If there are power poles, do they lean? If so, is the lean irregular between poles or symetrical through the area in question?

Most important, if you could address the issues I raised with the easement agreement itself, because it is still a little confusing. From whaat heas been described so far, I would not be considering the use of a geocloth, but I'm not going to rule it out yet.

KRS Services

http://www.krs-services.com

 

[layfieldman]

johnhan76

Geotextiles are not stiff enough to distribute load the way you are suggesting. Geotextiles have been used in roads before to prevent the movement of moisture and therefore help prevent the degredation of roads from freeze/thaw fluxes. Other products such as glassgrid can help distribute load because they do not stretch as much and therefore mobilize their strength much sooner than a geosynthetic.

Geosynthetics have been used in bridging voids in Europe where they have problems with right-of-way but these are not ordinary road fabric geotextiles, they have strengths in the region of 50kN/m right up to 1000kN/m.

In order to carry load in anyway the material must either be anchored or stiff enough that it will not just bunch up and fall into the hole. This can be accomplished by using a "tie back" length of up to 100m on either side of the void, depending on the diameter of the void.

 

[layfieldman]

I should also explain that the reason geotextiles are not normally used in roadway reinforcement, except for such locations such as logging roads, is that there is unacceptable deformation in the roadway before the geotextile is tensioned to the point where it will mobilize it's full strength.

 

[PWS]

Krsservices and others,
Easement allows me "ingress and egress" to land locked property that has been in family for generations. This bog road and one other road, accesses the land locked property. The easement crosses government land over both roads. The government is directing me to use the bog road since they are closing the other access road. The current easement allows access over any government land adjacent to the land locked property.
I'm beginning to understand the geofiber concept by the responses here. Most of the roadway is high enough to be stabilized by more fill of the correct type and grading. It is the two low wet spots that continue to sink and fill with water. The two low wet spots are about 6 yards long. If the geofiber was anchored in dry fill by wrapping around tree trunks layed across roadway and buried on both ends of the low spots would it hold?
Would cabling trees together to form corduroy topped by geofiber and then gravel be useful?

 

[Rex48]

You have not specified what sort of aggregate that you've been filling these two sinkholes with. I think I'd recomend excavation to a depth of 6-8 feet followed by refilling w/3-4 feet of 18-24" shot rock covered w/3 feet of 4-6" cobble, topped w/2-3 feet of 1 1/2" compacted crusher run. Inserting wood into an already saturated subgrade doesn't seem to make much sense and engineering fabric will never bridge such a large soft spot.
Rexcavator, E2H LLC

 

[swBausch]

Just wondering if geofoam could be of use in this situation...

 

[swBausch]

http://www.kingcountyjournal.com/sited/story/html/105532

http://199.2.132.200/domains/afp/html/faq_geofoam.html

 

[PWS]

swBausch,
Thanks for the info on geofoam. Looks like the perfect solution for this location. Low tech, low price, ease of placement, I just wonder if it comes in different colors...
I'm sure the township hasn't tried this technique and just might be interested enough to kick-in some funds to try this out.
PWS

 

[Juelson]

On the lower Kenai peninsula here in AK, we build corduroy roads with logs all the time thru muskeg. This is done quite often, usually with success and to the chagrin of high tech engineers......sorry fellas. A few years ago the borough upgraded the road that runs to my cabin, and instead of pulling up the coruroy that myself and my neighbors had laid down, they simply laid typar over it and then built the road from there. Eventually a log corduroy will rot. I have seen 30 year old corduroy roads that are still quite functional. Mind you, we are driving loaded log trucks and other heavy equipment over them also. If a log is completely submerged, it will last a long time. (the Japanese buy timber from AK and submerge the logs when they arrive in Japan, keeping them this way until needed. Sometimes the old technology is still the best!! 8^)

 

[bogtrotter]

how about the use of a geogrid rather than a fabric geotextile? i have have some designs done by a company called Tensar, for CBR's of 1, and they have come up with two layers of geogrid (of different strength) in a layer of 600mm crushed rock, and this is for commercial access (articulated trucks)to sites over approx. 6m of peat.