A LinkedIn article discussing the benefits of corporate alumni networks has mentioned the Chevron Bridges program managed by ACS. 

The article starts by discussing the mutual benefits of an alumni network and continues by talking about hiring, intelligence, customers and brand ambassadors as further benefits. The excerpt relating to Chevron is pasted below and you can read the full article on LinkedIn.

The first way an alumni network helps with hiring is making it easier for “boomerang” employees to return for another tour of duty after an absence from the company. Boomerangs are uniquely valuable because they offer an outsider perspective combined with an insider’s knowledge of company process and culture. An ex-employee will be more interested in returning if the company stayed in touch and maintained a rela­tionship in the interim. As the saying goes, Dig the well before you get thirsty. For example, the Corpo­rate Executive Board reports that rolling out the CEB Alumni Network doubled the firm’s rehire rate within two years.

Chevron takes things a step further with its Bridges program. Chevron alumni can sign up to be consid­ered for specific contract assignments. It’s an obvious win-win. Alumni get consulting opportunities that might turn into full-time gigs; Chevron gets a highly qualified pool of potential consultants whom it knows are a good cultural fit.