Construction occurs in a short time compared to the planning and operating phases. Yet construction is where major errors are made. Be prepared before starting. Make sure everything is in place, including;

5.2.1. Construction Contract

Contracts vary from as long as a book or a single page. In any case it is necessary to have a written agreement on what is to be done, even if the municipality is doing the construction itself. Here are basic items to be included in a construction contract:

• names of parties
• beginning and end of contract
• description of work by contractor
• responsibilities of contractee
• period of guarantee of performance by contractor
• payment schedule
• incentives for early completion and penalties for delays
• amount of earth to be moved in cubic meters
• location of site
• site concept drawing
  
• construction working drawings
  
• materials list.

5.2.2. Construction drawings

• To keep costs to a minimum, professionally drawn construction drawings by an engineer or architect are usually avoided unless legally required or the site has specific difficulties such as a steep slope, unstable soil for foundations, or other factors which require engineering services.

• The exception to this is the biodigester drawings which are usually pre-established.

• In any case it is advisable to have a construction contractor or manager assist with completing construction drawings.

• Changes during construction are noted on a separate set of working drawings. These are kept on the site and amended as operations and modifications proceed. This is the only way operators know construction history of the project.