In
addition to the uses allowed under ARM 36.15.601, the following artificial
obstructions may be permitted within the designated floodway subject to the
issuance of a permit by the permit issuing authority under the conditions set
forth in this rule and ARM 36.15.603 and 36.15.604:
(1) excavation of material from pits or
pools provided that:
(a) a buffer strip of undisturbed land of
sufficient width to prevent flood flows from channeling into the excavation is
left between the edge of the channel and the edge of the excavation;
(b) the excavation meets all applicable
laws and regulations of other local and state agencies; and
(c) excavated material is stockpiled
outside the designated floodway;
(2) railroad, highway, and street stream
crossings provided that the crossings are designated to offer minimal
obstruction to flood flow;
(3) limited filling for highway, street,
and railroad embankments not associated with stream crossings provided that:
(a) reasonable alternative transportation
routes outside the designated floodway are not available; and
(b) such floodway encroachment is located
as far from the stream channel as possible;
(4) Buried or suspended utility
transmission lines provided that:
(a) suspended utility transmission lines
are designed such that the lowest point of the suspended line is at least 6
feet higher than the elevation of the base flood;
(b) towers and other appurtenant structures
are designed and placed to withstand and offer minimal obstruction to flood
flows; and
(c) utility transmission lines carrying
toxic or flammable materials are buried to a depth at least twice the
calculated maximum depth of scour for the base flood. The maximum depth of
scour may be determined from any of the accepted hydraulic engineering methods,
but the final calculated figure shall be subject to approval by the permit
issuing authority;
(5) storage of materials and equipment
provided that:
(a) the material or equipment is not
subject to major damage by flooding and is properly anchored to prevent
flotation or downstream movement; or,
(b) the material or equipment is readily
removable within the limited time available after flood warning. Storage of
flammable, toxic, or explosive materials shall not be permitted;
(6) domestic water supply wells provided
that:
(a) they are driven or drilled wells
located on ground higher than surrounding ground to assure positive drainage
from the well;
(b) well casings are watertight to a
distance of at least 25 feet below the ground surface;
(c) water supply and electrical lines have
a watertight seal where the lines enter the casing;
(d) all pumps and electrical lines and
equipment are either of the submersible type or are adequately floodproofed;
and
(e) check valves are installed on main water
lines at wells and at all building entry locations;
(7) buried and sealed vaults for sewage
disposal in recreational areas provided that they meet applicable laws and
standards
administered by the department of health and environmental sciences;
(8) Public or private campgrounds provided
that:
(a) access roads require only limited fill
and do not obstruct or divert flood waters; and,
(b) no dwellings or permanent mobile homes
are allowed;
(9) structures accessory to the uses
permitted in this subsection such as boat docks, marinas, sheds, permanent
fences crossing channels, picnic shelters and tables, and toilets provided
that:
(a) the structures are not intended for
human habitation;
(b) the structures will have a low flood
damage potential;
(c) the structures will insofar as possible
be located on ground higher than the surrounding ground and as far from the
channel as possible;
(d) the structures will be constructed and
placed so as to offer a minimal obstruction to flood flows;
(e) the structures will be firmly anchored
to prevent flotation; and,
(f) service facilities within these
structures such as electrical, heating, and plumbing facilities are
floodproofed in accordance with ARM 36.15.901 through 36.15.903;
(10) all other artificial obstructions not
specifically listed in this subsection or in ARM 36.15.606, not allowed under
ARM 36.15.601, and not prohibited under ARM 36.15.605.