Temperature - European Investment Bank

WEST AFRICAN POWER POOL (WAPP) PÖYRY ENERGY LTD.
Mount Coffee HPP ESIA and RAP 2012-09-18
ESIA Report Page 217
Table 28-1: Main characteristics of the Mt. Coffee cascade
Parameter unit V-1 SP-4 SP-2 SP-1B MC
Location km a 187 b 214 c 122 85 24
dam height m 52 60 43 49 18.3
crest elevation m asl 248.8 253.7 175 129.2
average discharge m³/s 95.7 265.7 n.a. n.a. 564
Reservoir
area km² 208 8.1
FSL m asl 245 245 170 125.4 29
MOL m asl 228.5 232.75 168 123.4
tot. storage 10 6 m³ 4’950 450 110 200
live storage 10 6 m³ 3’400 305 110 200
Inst. capacity MW 132 none 214 120 66
a = km u/s from mouth of St. Paul River
b = on Via River, about 4.5 km u/s of its confluence with St. Paul River
c = on St. Paul river u/s of confluence with Via river; reservoir connected by channel to Via reservoir
d = no indications of res. area in Main 1982 report; figure from Stanley 2008, but referring to “Optimum“ Via,
with a smaller reservoir (FSL at 235.4 m asl) than the scheme proposed by Main (which probably
corresponds to the “Ultimate” Project in the Stanley report.
Note: the Main 1982 report contains some conflicting figures, e.g. on dam heights or reservoir volumes. In
general, the figures listed in summarising Tables are being used here.
Shortly, the different parts of the cascade can be described as follows:
� SP-4: dam on St. Paul River, with medium-sized reservoir, connected to V-1 by
a channel. No power plant, the only purpose of this structure is to divert water to
the large Via storage reservoir.
� V-1: dam on Via River, large reservoir with seasonal storage. The surface area
indicated in the Table above is for the “optimum” Via reservoir, the surface of
the final stage as shown in Figure 24-2 is probably closer to 250 km². The
reservoir provides storage volume for the entire cascade, retaining water during
the high flow season for being used during the dry season.
� SP2: dam on St. Paul river, with a rather large reservoir which, however, has a
rather small volume, not sufficient for seasonal storage. Operated as run-of-river
(ROR) plant.
� SP1-B: dam on St. Paul River with medium sized reservoir with no seasonal
storage capacity. Operated as ROR plant.
� MC: Mount Coffee HPP; existing/to be rehabilitated structure; dam on St. Paul
River; very small reservoir with very little storage. Operated as ROR scheme.
28.3 Prevailing Situation
Figure 28-4 below gives an indication of predominant land use forms and vegetation in
the St. Paul River basin.