Can someone help me with this layer(alkitran)

[xbat]

Hello there, Im new to this forum and I found the forum very informative and a lot of members are very helpful. so our project that we dugged are now in 40ft level below the ground, around 25 to 30 ft level we encounter the water filling up our site as we continue to the 40 to 45ft we encountered a very hard item even our backhoe cant break it. fortunately we cracked a piece of it and found out the it was a "stone" or seems more like a alkitran(asphalt). May I have some advice on how we can easily break this thing. does this layer have an item inside? I can post a picture here if you want to see the piece of this "stone".


Here is the piece of "stone" that we fortunately cracked out the layer.

 

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[Reanm8er]

Welcome! Sure, post the pics. Do you know whether or not you're working in fill?

 

[xbat]

Do you mean if Im working in philippines? yes somewhere in the philippines