View Public Works' open solicitations, and learn more about how to register as a supplier and submit a bid or proposal. A construction proposal is a document used to provide a client with a clear understanding of a project's details.The Allegheny County Sewer Authority (ALCOSAN) is seeking proposals, through this. A good construction proposal can be your showcase, your protection, a legal contract, and a great marketing and sales tool for your construction company. A brief narrative describing the proposed project. In this blog, we will teach you how to write an effective construction proposal that stands out from the competition. The proposal submission from qualified consultants should include the following: 1.