Concrete Interlocking Paver. Flagstone, Retaining Wall Installer. All Seasons Contracting, Inc is your local hardscape installer specializing in concrete interlocking pavers, sand set flagstone patios and segmental retaining walls. We have been serving the Yakima and Kittitas Valleys since 1994. Integrity and costumer satisfaction are our top priorities. Our team includes an ICPI trained and certified installer with 15 years of practical experience. We look forward to serving you. Services: •Concrete interlocking paver •Flagstone •Retaining Walls Call today to setup an appointment.