Engineered Septic system requires licensed engineer stamp in California

I am looking to have an engineered septic system designed in California and require the services of a licensed engineer to stamp the design documents for submission to Environmental Health. I can prepare the plot plan with the subsurface drip lines and tanks shown. The home has an operational septic system already. It needs a design for the back up system because we cannot install a standard septic system in the available backup systm area. I need the project completed within 1 month, and the desired capacity for the septic system is for a 2 bedroom backup system only.