Why do water lines freeze when weather warms up 3

[johmue]

We are having problems with water lines freezing this spring can anyone tell me why this happens when the weather warms up outside?
Does the water from on top of the ground tranfer the cold through surface cracks to the waterlines below and when we see a couple of cold nights it freezes again freezing the water lines with it?
In the spring why does the ground drop in an area for no apparant reason I have seen holes 2' in diameter and 12" deep where once hard ground was and it is soft like alkaline mud.
Frost heaves I can justify by the water under the grounds surface expanding and forcing the ground up. But the holes? Is it from the water freezing durring the winter and when it melts in the spring the ground drops into the void created by the water that had been frozen?
A lot of questions probably with a simple answer. Can anyone help me out?

 

[CarlB]

I think I can help on part of your question. It is not unusual for water lines to freeze in the spring. This is almost certainly due to the ground temperatures at depth, which are still cooling. The cold winter temperatures move slowly into the ground. Say annual temperatures vary by 100 degrees at the surface; this variation drops to nearly zero at say 20 feet. This phenomenon is represented by the classic "whiplash" or "trumpet" curves. The "frost depth" (level where T=32 degrees F)moves down during the winter, and due to insulating value and specific heat of the soil, can continue to deepen even after the surface is warming.

 

[KRSServices]

Frost appears to migrate into the ground, and in a sense I suppose it does. The reality however, is that the freezing tempuratures causes the ground to lose (or give up heat). During the winter months, sustained cold tempuratures creates a fozen lens, or plug if you will. Due to the difference of temperatures between the plug and the ground, the ground will continue to lose heat and freeze until an equilibrium is achieved (where in the spring warmer tempuratures cause the plug to disintegrate from the top down). This behavior is similar to ice on a lake. In the spring, the warm weather warms the ground which causes the soils to begin retaining heat on the surface, but down below the frost plug, the soils continue to give up heat. In cold winters where there is a large number of cold degree days, the plug is very cold and the level of penetration will be quite deep (relative to local conditions). Waterlines (3/4" service lines) at those depths will freeze relatively quickly if the water does not recirculate or heat is added. The soil temperatures outside the waterline would have to be below -3 Celcius for the freezing process (nucleation into crystals) to begin in earnest.

KRS Services

http://www.krs-services.com

 

[KRSServices]

As to the second question, the mushy soft soil is due to the fact that the soils beneath have not yet absorbed (or perhaps still frozen) the spring meltwater. The holes are caused by the soils shifting and filling the voids left from uncompacted trench backfill or poorly compacted (disturbed) soils after the high moisture is disbursed. Typically, I usually see these types of disturbances on properties at service trenches. Two years ago, I fielded a call from a resident whose service trench had settled nearly 20 years after the original construction. No, there were not any leaks or anything like that, but the frost in that year went down close to 9 feet.

Lastly, in relation to frost, I have excavated frost in the first week of June at the 4.5 to 7.0 foot depth, again, under a roadway after a miserably cold winter. KRS Services

http://www.krs-services.com

 

[montrealer]

i guess that the wetter the soil, the more conductive it is. maybe in spring, the water seeps into the soil after the icecap melts. the more conductive soil transmits the cold temperature below and thus possibly freezing below grade is more intense in spring.

 

[tylermacleod]

johmue,

when frost susceptible soils thaw they loose strength and holes can develop. there are two key factors that contribute to this phenomenom.

i) the density of the soil has been decreased to accomodate room for ice lenses that cause the ground to heave

ii) the thaw typically occurs at a rate faster than the melt water can drain

the soil is essentially loosened and saturated. As a result the bearing capacity is significantly reduced. This will lead to failures (holes) if the bearing capacity is reduced below the overlying loads.

I am not sure about why pipes in freeze in the spring but it may be due to the sometimes daily variation of temperatures from below freezing to above freezing. During the day snow in the area may melt increasing the water in the ground which will freeze at night and greatly increase the thickness of ice in the ground (greater heave). this may crush your pipe.

regards

 

[KRSServices]

Nope, Nope, Nope!

Spring is the worst time for freezing pipes because that is when the frost has penetrated the deepest! It has nothing, I repeat nothing, to do with warm air temperatures. It has everything to do with how cold the winter was (in degree days and time) relative to the "R" factor of the soils and subsequent heat loss of those soils. Think about it. When you have the freezing in the fall....do the pipes freeze? KRS Services

http://www.krs-services.com

 

[Leal]

I think the problem is also related with the "Kelvin Efect" that occurs when you have water in thin tubes (you can consider the soil as a series of tubes. In this thin tubes the water frosts at temperatures greater then normal.