NA-05 - Cleaning: Solids in Drain and Sewer Systems (Demo)

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Fundamentals
Origin of solids
Transport behaviour of solids
Consequences of solids entry

Origin of solids

Solids entry through extraneous water (3)

a) Well compacted cohesive soil

b) Poorly compacted cohesive soil

Image: Erosion of cohesive soils as a result of a leaking gravity sewer located within the ground water zone [Stein00f] [Jones84a].

Stein00f

Stein, D.; Falk, Ch.; Schlüter, M.: Empfehlungen für Kanalreinigung. Institut für Kanalisationstechnik (IKT) (unveröffentlicht), Gelsenkirchen, 2000.

Jones84a

Jones, G. M. A.: The Structural Deterioration of Sewers. International Conference on the Planning, Construction, Maintenance & Operation of Sewerage Systems. Reading (England), 12.-14. Sept. 1984. Paper C1, S. 93-108.

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With cohesive soils specified by DIN 1054 (clays, clayey silts and silts mixtures with non-cohesive soils), if the proportion of particles sized < 0.06 mm is more than 15%, the solid entry at the pipe failure is mainly caused by the soil erosion through the internal stresses within the pipe. This occurs in cracks with a width ≥ 6 mm and a leak size > 60 cm² [[DIN1054:2010]] [Dohma2004a] [Dohma99] [[ASTM D2487-17]] (Refer to relevant standard(s) in your jurisdiction).

DIN1054:2010

DIN 1054: Subsoil - Verification of the safety of earthworks and foundations - Supplementary rules to DIN EN 1997-1 (12.2010)

Dohma2004a

Dohmann, M.; Hennerkes, J. (2004): Untersuchung des Einflusses undichter Abwasserkanäle auf die Standsicherheit des umgebenden Bodenkörpers, Abschlussbericht zum Forschungsvorhaben des MUNLV NRW, Institut für Siedlungswasserwirtschaft der RWTH Aachen

Dohma99

Dohmann, M. (Hrsg.): Wassergefährdung durch undichte Kanäle - Erfassung und Bewertung. Springer Verlag, Berlin 1999.

ASTM D2487-17

ASTM D2487-17e1: Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System), ASTM International, West Conshohocken, PA, 2017, www.astm.org)