Although sand filters are closed and therefore have minimal runoff reduction, they are common at nearly every stormwater hotspot. Here you can download design specifications, and learn about the visual indicators to inspect and maintain sand filters.
Design Specifications:

Inspection and Maintenance:
A guide to inspecting and maintaining sand filters can be found in the Bioretention Illustrated Guide:
Improving Performance:
CSN Webcasts:
[Webcast] The Potential to Enhance Nutrient Removal in Bioretention and Sand Filters
[Webcast] Visual Indicators for Infiltration, Surface Sand Filters and Permeable Pavement