7. Outfall Structures and Maintenance: In the July 21, 1999, Federal Register notice, we proposed to modify NWP 7 to authorize maintenance excavation, including dredging, to remove accumulated sediments from intake or outfall structures and canals associated with these structures.
Several commenters stated that the maintenance activities authorized by the proposed modification of this NWP are exempt from permit requirements. Numerous commenters indicated that the removal of accumulated sediments should be authorized by NWP 3 and that the modification of this NWP is unnecessary. Several commenters requested clarification regarding what types of maintenance activities are authorized by this NWP. Another commenter said that the Corps should withdraw the proposed modification. This commenter also recommended prohibiting removal of material in special aquatic sites and small impoundments. One commenter said that the construction of outfall structures that does not involve discharges of dredged or fill material into waters of the United States should not require a Corps permit.
Maintenance dredging to remove accumulated sediments from intake and outfall structures in Section 10 waters is not exempt from Corps permit requirements. Although the removal of accumulated sediments in the vicinity of existing structures is authorized by paragraph (ii) of NWP 3, there are maintenance dredging or excavation activities associated with intake and outfall structures that do not meet the terms and conditions of NWP 3 and could be authorized by NWP 7. The text of this NWP clearly states which maintenance activities are authorized by NWP 7. District engineers will review PCNs for maintenance activities in special aquatic sites and small impoundments to ensure that the adverse effects on the aquatic environment are minimal. Outfall structures constructed in Section 10 waters require a Corps permit, even if there are no associated discharges of dredged or fill material into waters of the United States.
One commenter said that acreage and linear limits should be imposed on this NWP. Several commenters contend that this NWP should not authorize activities in tidal waters or special aquatic sites. One commenter stated that this NWP should not authorize maintenance activities associated with aquaculture facilities or power plants. A commenter remarked that maintenance excavation and dredging activities could result in more than minimal adverse effects on the aquatic environment and that notification should be required for all activities authorized by this NWP. Another commenter objected to the requirement for notification for all activities authorized by this NWP.
We do not agree that it is necessary to impose acreage or linear foot limits on the activities authorized by this NWP or restrict the applicable waters because all activities authorized by this NWP require notification to the district engineer. The removal of accumulated sediments from outfall and intake structures associated with aquaculture facilities and power plants is necessary to ensure the efficient operation of these installations. The district engineer will review these PCNs to ensure that the NWP authorizes only those activities with minimal adverse effects on the aquatic environment.
One commenter said that delineations of special aquatic sites should be limited to the impact area or within 200 feet of the proposed activity. Two commenters stated that it is unnecessary to require delineations of special aquatic sites since this NWP authorizes maintenance activities. One commenter remarked that there should be a provision in the NWP that allows maintenance of existing structures when the original design capacities and configurations are not available. Another commenter said that paragraph (d) of the proposed modification should be removed because this requirement is already addressed by General Condition 3.
The text of this NWP states that the requirement for delineations of special aquatic sites is limited to the vicinity of the proposed work. The delineation of special aquatic sites, especially vegetated shallows, is necessary to ensure that the NWP authorizes only activities with minimal adverse effects on the aquatic environment. If the original design capacities and configurations of the facility are not available, district engineers will use their judgement to determine if the proposed work is authorized by this NWP. The requirements of paragraph (d) of this NWP and General Condition 3 are not the same. Therefore, we believe that paragraph (d) is necessary to ensure that NWP 7 authorizes only activities with minimal adverse effects on the aquatic environment.
In response to a PCN, district engineers can require special conditions on a case-by-case basis to ensure that the adverse effects on the aquatic environment are minimal or exercise discretionary authority to require an individual permit for the work. The issuance of this NWP, as with any NWP, provides for the use of discretionary authority when valuable or unique aquatic areas may be affected by these activities. This NWP is subject to General Condition 25, which restricts its use in designated critical resource waters. NWP 7 is reissued with the modifications discussed above.
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