Storm Manage · Decision tool

Site Type to Grade and Wrap Selector

The runoff destination decides the system type. What sits on the surface decides the load grade. This is the second axis — pick the surface and the depth band and it returns a grade shortlist, the wrap that goes with your destination, and which sector page carries the detail.

Step 1 · What is built above the tank Soft landscape, pitch or planted deckNon-trafficked, or maintenance vehicles only Pedestrian area or private drivewayFootways, courtyards, single-dwelling driveways Car park or light access roadCars and light vans, estate roads, parking courts HGV yard, hardstanding or industrial apronHeavy goods vehicles, plant traffic, port and airport areas Highway carriagewayAdopted road under a highway authority

Step 2 · Cover depth over the top of the tank Shallow — under about 600 mmConstrained vertical zone, deck build-up, shallow services Normal — roughly 600 mm to 1.5 m Deep — more than 1.5 m

Step 3 · Destination from the router Infiltration — water leaves through the ground Controlled release — attenuation, detention or OSD Reuse — rainwater harvesting

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Grade shortlist — starting point, not a sign-off

Item	Result
Wrap
Material
Module height
Governing load case
Sector page

Request a load-class spec sheet written against these parameters →

Grades quoted are Storm Manage short-term compression designations, not allowable design loads. A design value has to come from a structural calculation to CIRIA C737 against your own cover depth, traffic loading and groundwater condition, with creep and installation-damage reduction applied. Storm Manage does not hold a BS EN 17151 long-term creep report and does not issue signed 50-year allowable loads.