Need advice on filling the choke pit for a house in Thanjavur,TN

Dear sir

The septic tank in my house use to fill every year. I have been suggested to create a choke pit near the septic tank. The measurement proposed is   3.5*3.5*4 feet. I have purchased sand and 1.5 Jalli to fill the choke pit. I like to fill the choke pit myself. Kindly guide me how to place the sand layer and Jalli layer. Suggest the  width of the plastic pipe used to bring out the water to choke pit from septic tank. How can the choke pit be closed or kept open.

Thanking u


With Regards