| CPC F16L 59/15 (2013.01) [E02F 5/223 (2013.01); F16L 1/028 (2013.01); F16L 59/04 (2013.01)] | 16 Claims |

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1. A filled trench comprising:
a pair of conduits of one or more thermal energy distribution systems, the pair of conduits being configured to deliver fluid with a different temperature in each of the conduits, the pair of conduits being circumferentially surrounded by particulate filling material on all sides thereof as seen in the vertical cross sectional side view of the filled trench;
a first section filled with a particulate filling material of a first type, wherein the first filled section of the filled trench occupies a space in between the pair of conduits; and
a second section filled with a particulate filling material of a second type, wherein both of the pair of conduits are surrounded by the second section;
wherein the first section separates the second section into two spaced apart portions;
wherein the filling material of the first type has a first thermal conduction coefficient and the filling material of a second type has a second thermal conduction coefficient, wherein the first thermal conduction coefficient is smaller than the second thermal conduction coefficient; and
wherein the first section and the second section are horizontally separated from each other, as seen in a vertical cross sectional side view of the filled trench.
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