“Soil Survey Map of (the) County of Welland” print by the Experimental Farms Service, Ottawa (1935)

Yes, this is a map of the County of Welland rather than the City of Welland, but it's also the most colourful and unique image I could find of the city. At bottom is the soil guide legend, allowing you to determine that your Grandpa's house just southwest of town was indeed on caistor clay loam, a substrate good for "general farming and dairying with pasture, hay, wheat, oats, barley, corn, and buckwheat". 

A reproduction available at 16x12" or 24x18" on Epson Enhanced Matte 192 gsm paper printed with Epson UltraChrome XD2 archival ink. Sold in an open edition, unframed. Based on this original public domain image held by the Brock University Map, Data, and GIS Library.