PPRN — Restricted area of the PSS of the municipality of Tonnoy (54527)

Submersible Surface Planes (PSS) are the first mapping documents regulating land cover in flooding areas for federal watercourses. They were created by the Decree-Law of 30 October 1935 and its implementing decree of 20 October 1937. The Barnier Law of 2 February 1995 gives PSS a risk prevention plan (PPR) status, making them enforceable against third parties. The PSS is a document that establishes a utility easement affecting land use. It allows the administration to oppose any action or work likely to impede the free flow of water or the conservation of flood fields (Article R425-21 of the Urban Code). The filing of a declaration before carrying out works likely to affect the natural flow of water (digues, embankments, depots, fences, plantations, constructions) is therefore necessary. Although having the same legal value, PSS and PPR are technically different. SSPs “merely” map a flood hazard in contrast to PPRs that represent a risk taking into account the vulnerability of the territories (regulatory zoning plan). Finally, the PSS mapped a so-called “average” flood less than the reference flood used as the basis for the development of PPRs (the highest known flood corresponding to the highest known waters (PHEC) and, in the event that it was lower than a centennial flood, the latter). Pursuant to Article L562-6 of the Code de l’Environnement, the PSS are to be PPR pending their repeal by a PPR on the municipalities concerned. For natural PPRs, the Environmental Code defines two categories of zones (L562-1): risk-exposed areas and areas that are not directly exposed to risks but where measures can be foreseen to avoid exacerbating the risk. Depending on the hazard level, each area is subject to an enforceable settlement. The regulations generally distinguish three types of zones: 1- ‘Building prohibited areas’, known as ‘red areas’, where the hazard level is high and the general rule is the prohibition on construction; 2- ‘prescribed areas’, known as ‘blue zones’, where the hazard level is average and the projects are subject to requirements adapted to the type of issue; 3- areas not directly exposed to risks but where constructions, works, developments or farms, agricultural, forestry, craft, commercial or industrial could aggravate risks or cause new ones, subject to prohibitions or requirements (cf. Article L562-1 of the Environmental Code). The latter category applies only to natural RPPs.