567—72.11(455B) Miscellaneous construction. The following criteria shall apply to miscellaneous construction.
	72.11(1) Structures, obstructions, or deposits.
	a. 	Location. Miscellaneous structures, obstructions, or deposits shall not be located so as to individually or collectively conflict with 567—75.4(455B) governing the establishment of encroachment limits.
	b. 	Protection. Miscellaneous structures, obstructions, or deposits shall be provided with the minimum level of flood protection associated with the designated damage potential as indicated in 72.5(1) governing buildings and building complexes.
	72.11(2) Excavation.
	a. 	Spoil. Spoil material resulting from an excavation shall be disposed of in a manner consistent with 72.11(1)“a” pertaining to miscellaneous structures, obstructions, or deposits.
	b. 	Levees. Levees protecting excavations shall meet the requirements of 72.11(1)“a” pertaining to miscellaneous structures, obstructions, or deposits.
	c. 	Control of surface runoff into rock quarries. When the department investigates an application for approval of excavation of a quarry in carbonate rock on a floodplain or floodway, the department shall consider the potential for pollution of an underground watercourse or basin from drainage of surface water into the quarry. If available information including topographic and geological information support a finding that drainage of surface water into the quarry would constitute a violation of the permit requirement in Iowa Code section 455B.268(3) and might cause pollution of an underground watercourse or basin if not controlled, then the department shall require that the applicant either request a permit under Iowa Code section 455B.268(3) and rule 567—51.5(455B) to authorize drainage of surface water into the quarry, or construct and maintain a means of controlling drainage of surface water which would otherwise drain into the quarry.
	72.11(3) Structures or materials across a channel. The following criteria shall apply to structures or materials such as riprap that span the channel of a stream or river and do not meet the thresholds of rule 567—73.3(455B):
	a. 	The location and design of the structure shall not adversely affect the fisheries or recreational use of the stream.
	b. 	The pool created by the structure shall not adversely affect drainage on lands not owned or under easements by the applicant.
	c. 	The structure shall be hydraulically designed to submerge before bankfull stage is reached in the stream channel in order that increased or premature overbank flooding does not occur. Where this cannot be reasonably accomplished in order for the structure to fulfill its intended purpose, the applicant shall demonstrate that any increased flooding will affect only lands owned or controlled by the applicant.
	d. 	For projects that include significant appurtenant structures or works outside the stream channel, the combined effect of the total project shall not create more than one foot of backwater during floods which exceed the flow capacity of the channel, unless the proper lands, easements, or rights-of-way are obtained.
	e. 	The structure shall be capable of withstanding the effects of normal and flood flows across its crest and against the abutments with erosion protection added as required to prevent failure of the structure during flood events.
[ARC 5899C, IAB 9/8/21, effective 10/13/21]