146 KEPOUT — 187^. 



Section YI. — Merthi/r Tycljil Scwar/e-Farm at Troechjrhlw. 



In January last the attention of the Committee was directed to a system 

 of purifying sewage by intermittent downward filtration which was then 

 completed at Troedyrhiw, near Merthyr Tydfil, for dealing with the sewage 

 of the latter place. 



In 1870 the present Eivers Pollution Commissioners, in their first Eeport, 

 described some most important experiments which had been conducted in 

 their laboratory by Dr. Edward Fraukland, F.R.S., which satisfactorily proved 

 that intermittent downward filtration (which is, in fact, irrigation confined to 

 a small area), " properly conducted, is a most efficient means of piuifying 

 sewage." The various trials with different soils showed conclusively that 

 town sewage might in this manner be cleansed and rendered sufficiently 

 innocuous for discharge into streams. The Commissioners stated that an 

 acre of filtering material G feet deep would so cleanse the sewage of 3300 

 jicople ; but they expressed an opinion that, whilst successful from a remedial 

 point of view, the system would be very wasteful, as not utilizing the valuable 

 manurial properties of sewage : and for this reason it was only to be recom- 

 mended for employment on a small scale, or where circumstances rendered 

 other processes difficult and expensive. 



In 1868, and again in 1869, injunctions were granted by the Court of 

 Chancery to prevent the Local Board of Merthyr Tydfil from discharging the 

 sewage of that town into the river Taff. 



Merthyr Tydfil contains a population of 50,000; but, according to informa- 

 tion supplied to the Committee, the excretal refuse of not more than two fifths 

 of this number is discharged into the sewers, although the slops and other 

 liquid refuse from a further like number (20,000) is stated to be admitted. 

 It is not surprising, therefore, that the sewage is, as afterwards appears,, 

 exceedingly weak. 



In 1870 the Local Board gave notice for the purchase of 393 acres of land 

 in the valley of the Taff, upon which to dispose of the sewage. Of this 

 quantity 70 to 80 acres were purchased below the village of Troedyrhiw, 

 which is about three miles from Merthyr Tydfil ; and it is here that an area 

 of about 20 acres has, under the supervision of a member of the Committee, 

 been converted into a filter-bed for the practice of the system of downward fil- 

 tration originated by the Rivers Pollution Commissioners, as above described. 



The soil of this area consists of a deep bed of gravel (probably the former 

 bed of the river TafP, which is embanked upon the east side, and is raised 

 above the valley), composed of rounded pebbles of the Old Ilcd Sandstone and 

 Coal-measure formations, interspersed with some loam and beds of sand, 

 forming an extremely porous deposit, and having a vegetable mould on the 

 surface. 



The land has been pipe-drained at a depth of less than 7 feet, and the 

 pipes are concentrated at the lowest corner, where the effluent water is dis- 

 eiiarged into an open drain, which leads to the river Taff at some distance 

 down the valley. 



The area is laid out in square beds, intersected with roads and paths, along 

 which are constructed the main carriers which receive the sewage from the 

 outfall sewer and distribute it over the beds. 



The sewage before entering the farm is screened through a bed of " slag," 

 which arrests the coarser matters. It is applied to the land intermittently ; 

 for the area being divided into four plots or beds, it is turned on each one 



