Pond Boss Forums POND CONSTRUCTION Soil questions Soil Question

I have searched and read many threads about clay and compaction.

My soil is as follows;

"Ap--0 to 6 inches; dark brown (10YR 3/3) loam, brown (10YR 5/3) dry; weak medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many very fine roots; common very fine tubular and very fine irregular pores; moderately acid (pH 5.6); clear smooth boundary. (5 to 7 inches thick)

A--6 to 14 inches; brown (10YR 4/3) loam, yellowish brown (10YR 5/4) dry; weak medium subangular blocky structure; hard, friable, sticky and plastic; many very fine roots; many very fine and few fine tubular pores; strongly acid (pH 5/4); clear smooth boundary. (4 to 8 inches thick)

BA--14 to 22 inches; strong brown (7.5Y 5/6) clay loam, light yellowish brown (10YR 6/4) dry; common dark yellowish brown (10YR 4/4) coatings on vertical faces of peds; moderate coarse and medium subangular blocky structure; hard, friable, sticky and plastic; common very fine roots; many very fine and fine tubular pores; strongly acid (pH 5.2); clear smooth boundary. (0 to 8 inches thick)

Bt1--22 to 30 inches; dark yellowish brown (10YR 4/6) clay loam, yellowish brown (10YR 5/6) dry; moderate fine subangular blocky structure; hard, firm, very sticky and plastic; common very fine roots; many very fine and few fine tubular pores; few distinct dark brown (7.5YR 4/4) clay films; strongly acid (pH 5.2); clear smooth boundary. (6 to 8 inches thick)

Bt2--30 to 39 inches; dark yellowish brown (10YR 4/6) clay, yellowish brown (10YR 5/4) dry; moderate fine subangular blocky structure; hard, firm, very sticky and plastic; few fine roots; many very fine and few fine tubular pores; common distinct dark brown (7.5YR 4/4) clay films; strongly acid (pH 5.4); clear smooth boundary. (7 to 9 inches thick0

2Bct--39 to 49 inches; strong brown (7.5YR 5/6) clay, very pale brown (10YR 7/3) and pale brown (10YR 6/3) dry; moderate coarse prismatic structure; extremely hard, very firm, very sticky and very plastic; common distinct dark brown (7.5YR 4/4) clay films; few very fine roots; common very fine tubular pores; strongly acid (pH 5.4); abrupt smooth boundary. (8 to 10 inches thick)

2C--49 to 60 inches; mottled yellowish brown (10YR 5/6 and 10YR 5/8) gray (10YR 6/1) and light olive brown (2.5Y 5/4) clay; massive; very firm, very sticky, very plastic; few very fine tubular pores; few medium slickensides; strongly acid (pH 5.4)."

To my eyes it is heavy clay with little water absorption from the topsoil. We even have problems with trees and plants getting water because of our clay.

Question is, it seems I would still need to add soil to mix with bentonite above the clay I already have correct? It seems to hold water currently in the small test holes I dug and doesn't seem to crack much in the dry heat of summer (Oregon so our temps are generally between 30 in winter and 90ish in summer). Not sure if soil and bentonite mixed and compacted with a sheepshead would still be needed according to our soil info above.

Thanks for any replies or pointing me to similar threads that may answer this.

Thanks in advance,

BRAD

The textures above 49" have well drained soil colors. Where is the water source for your proposed pond? Its not in this soil. Also the layer from 49 to 60" has clay texture with slickensides, indicating the presence of expansive clays. These, to some degree should expand when wet, but contract (crack) when dry.

Brad, there are a ton of folks on this forum that can help but I suggest providing a few more details, such as:

Is this an excavated or embankment pond?

How deep will you be excavating in either case?

Did the soil tests provide a "% passing No 200 sieve"?

Were these samples taken from borings or excavated test holes, and how many sample locations?

What is surface area of pond?

You may have enough clay to manipulate and cap/core over/around any problem areas, without the cost of brining bentonite in. Key is to find an experienced and honest contractor and like President Reagan always says, trust but verify. I have what I believe is a pretty air tight pond contract both from technical and commercial perspective, and am happy to share it if you'd like to look at it. I just built a 5 acre pond in pretty volatile soils but had enough clay to really make a great impermeable liner and dam core trench, etc and its held like a jug for several months now. Message me your email if you'd like to take a look at the contract.

Normally you can take the good clay that is excavated and spread it over the other layers and compact it to seal. That is what you are doing when you add bentonite and work it in.