The woman, from Waterloo, who does not wish to be named, suffered a broken jaw, a double fracture to her right ankle, plus cuts and bruises, when she was struck by the collapse of the 2m earth-retaining wall.
Kirklees Magistrates sentenced Lee Marsden, director of MWK Group LLP, after he pleaded guilty to breaching the Health and Safety at Work etc Act 1974.
The court was told an investigation by the Health and Safety Executive (HSE) after the incident on 9 September 2011 found Marsden failed to ensure the wall was properly built to withstand the pressures of an earth-retaining structure.
Marsden had been involved first-hand in the work on site and directed the other workers on the build. During the construction, cracks began to appear in the wall. Work was temporarily halted but adequate precautions were not taken to ensure the safety of the residents in the house.
Magistrates fined Lee Marsden, of Dewhurst Road, Fartown, £140 and ordered him to pay £100 in costs. Mr Marsden, who represented himself, no longer works.
After the hearing, HSE Inspector Dave Stewart said: “Construction work should only be undertaken by those competent to do the job safely in accordance with a design that deals with the specific risks. Mr Marsden did not recognise the dangers posed by the structure he built, which was incapable of retaining the forces exerted upon it.
“He also failed to prevent access to the wall when cracks appeared, and it was recognised as unstable. The wall did collapse and, sadly, the householder was in the garden at the time and was seriously injured.
“Building contractors should engage competent engineers to advise on suitable designs for structures that will be subject to considerable loads. Inadequate design is a major cause of structural failure – the consequences of which can be serious and often fatal.