Runoff volumes

Hello, I have a question regarding silt and run off. Our project is located in Phuket Thailand. Our project is planning to have a series of retention ponds and bioswales to collect rain water runoff. The storms though have occasionally hit with great intensity in the last few years. What happens if a storm comes that exceeds the 2 year 24 hour limit, which is quite possible here and overwhelms the system resulting in some erosion. There would be silt that would enter the ocean the project is located on. Does that effect the credit standing in any way?