flooded yard

MKramer, sounds like you need a new drainage system. If the cistern to which you referred was acting as a storage reservoir for holding the “maximum storm event” volume of water, and you filled the cistern with stone, then you have reduced the previous storage volume by as much as 60%, or possibly more.

If the cistern was also acting as a seepage pit, then the infiltration rate of water into the soil below and around the seepage pit is a naturally declining rate. It could be that the infiltration rate has declined to the point where the volume of water from a significant storm event cannot possibly infiltrate into the soil at the required rate.

Compaction of the soil, which reduces the infiltration rate, may have occurred from heavy equipment being driven on the site during the construction of the addition.

I will not make specific recommendations for a potential design for your very specific situation. Too many potential site constraints which affect design considerations.

I suggest that you contact a drainage engineering firm in your area. They will perform a site visit, and then prepare adequate designs which mitigate the problems posed by various site constraints on your specific site.

You can then decide whether to install the system yourself, or contract with a professional system installer.

If the ponded water has the potential to flow onto your neighbors property, and damage occurs to their property from flooding, then I would feel a whole lot better if the situation were handled by a licensed, insured, professional system installer.

On the other hand, if you decide to install the system yourself, if the system design is relatively simple, and if the potential for damage to the neighbors property is minimal if the system fails, then you could save from 40% to 50% of the cost of having a professional installer complete the job.

I view the extra expense as an investment in my peace of mind, and the insurance protection provided by the installer. JWA