DPWH Standard Specification for Item 1719 - Underdrains and Flap Gates. Category: Department OrderSub Category: construction-materialsSeries: 2018No: 44File: DO_044_s2018.pdfDate: Friday, March 16, 2018Tags: DPWH Standard Specification for Item 1719 - Underdrains and Flap Gatesmaterials BRS 044Bureaus and Services: Bureau of Research and Standards Read more about DPWH Standard Specification for Item 1719 - Underdrains and Flap Gates.