NOTE: This examples are old, you're probably better off looking here now: https://github.com/Unity-Technologies/LWRP-CustomRendererExamples
Tested in Unity 2018.3.0b3 and LWRP 4.0.1.
Examples for extending the LWRP
Ported the "Blurry Refractions" sample from the Graphics Command Buffers page
Open the Sample scene to see them both working together.
Notes on extending the LRWP in general can be found in the wiki of these repo.