Veteran Needs New Septic

My husband and I bought our house in October 2018. When we bought the house we were told the septic was in good working order. However, the first time it rained and we were unable to flush the toilets we knew something was wrong. We had the septic pumped out and we had a plumber fix a pipe that wasn't connected to the house and septic tank. The plumber found a 55 gallon drum inserted into the leeching fields with a pump, which is illegal. The Department of Environmental Quality has been notified and if we don't fix the issue we could be fined. The testing we had done on our property shows we need an aerobic septic system, which is basically a mini sewage plant that will need monthly upkeep and pumped every 2 years.
My husband is a disabled veteran, he is rated by the VA as 100%. Our sole income is his pension he receives every month. I have been looking for work with no luck. We have looked into every grant and financial aid we could find in Oklahoma, and we don't qualify for any of them. We have cut back on a lot of things to save money to pay for the new aerobic system, but we are coming up short. We are a family of 5 and are trying the best we can. We don't usually ask for help, especially not for money, but we are desperate and need some help.