Hi There,
I hold a bachelors and masters degree in geology and I am a Geotechnical Engineer for a major UK and global engineering consultancy. Soakaway design is something i do as part of my job and my previous job also.
I can carry out the technical aspects of the design but I would need some information from you, such as rainfall,surface areas etc but this can be confirmed later. I can also provide you instructions on how to carry out a infiltration test for better results rather than using estimated values.
I can do the design for you (subject to you providing the information) for 200AUD, and for an additional 100AUD I can walk you through the steps and process of doing an infiltration test.
Best wishes,
Lawrence