When people are building houses they avoid making a toilet in the basement to avoid the hassle and long term costs accossiacted with the plumbing and pump.. doing it on already constructed house is again double the trouble.
As I am aware of LDA rules digging in basements is not allowed and is illegal. DHA rules are more strict and impossible to by pass, I happen to know a fellow who recently constructed a house in DHA and due to inexperienced labour the front elevation was 3" higher then the DHA allowed limit he ended up paying almost 1.5 million in fine.
So even if it is allowed by DHA and if the fee imposed is economically viable then there are 90% chances you will end up ruining your house because every other thekaydar will tell you how easy of a task it is and is fully capable of doing it but in reality you never know untill the very end..