Sump pump crock??

I am revamping my drainage situation in the crawl space of my house. In the spring I get water in the crawl. I took out the old crock and pump. The latter recently failed. I bought two new submersible pumps and two crocks, so I can have a redundant system.
Here is my question. There was no drainage pipe laid in the crawl when the house was built. The area is just lower where the old pump was. When I put these new crocks down, should I put any holes in them? If so, where? Should I put gravel around them? The soil is sand.
Thanks, Tom

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