Orphanage Laundry

In Kenya, far in the back country, outside the Masai Mara Conservancy to the south of the country, there is a unique orphanage, called the Tania Rehabilitation Center.  Here is where all the most difficult "situations" come in the form of orphaned children from around Kenya.  Many children born deaf or blind or gone deaf or blind by childhood diseases and many other handicapped children who have survived against all odds.  In all, there are about 175 children supported by 20 dedicated care givers at the facility.  
Laundry is still done by hand and dryed on the line or thorn bushes.  Some of the developmentally handicapped children "soil" themselves several times a day.  It takes three people All Day, Every Day to do the laundry.
I would like to build them a simple, manually-powered, clothes washing machine that should assist in the back breaking work of clothes washing, which is taditionally done in a basin on the ground, standing, bend at 90 degrees, scrubbing vigorously with lye soap.