maintenance of cpwd colony parks 2020-21 . sh field preparation through trenching at shanti path and supply of vermi compost and neem oil cake . sh field preparation through trenching at shanti path and supply of vermi compost and neem oil cake . , trenching in ordinary soil up to a depth of 60 cm including removal and stacking of serviceable materials and then disposing of surplus by spreading and neatly leveling with in a lead of 50 m and making up the trenched area to proper levels by filling with earth or earth mixed with sludge or / and manure before and after flooding trench with water ( excluding cost of imported earth , sludge or manure ) , supply of neem oil cake in 50 kg . packing . , supply of vermi compost in 50 kg . packing .