N.J. Admin. Code § 7:13-11.4

Current through Register Vol. 56, No. 24, December 18, 2024

Section 7:13-11.4 - Requirements for a regulated activity in a flood fringe

(a) This section sets forth specific design and construction standards that apply to any regulated activity proposed in a flood fringe.

(b) This section provides standards for the volume of material that may be placed aboveground in a flood fringe as well as other activities that would reduce the flood storage volume on a site. When material is placed aboveground in a flood fringe, it will occupy a space that would otherwise be filled with floodwaters during a flood, and, thus, will reduce the flood storage volume on the site. Construction also reduces the flood storage volume by preventing floodwaters from entering a space that it would otherwise occupy, such as the space inside a building or stormwater management basin, or behind an embankment. For example, although the space within a building may be empty, the building's walls might prevent floodwaters from entering that space. Since the entire space within the walls has been rendered inaccessible to floodwaters, the entire space, though empty, displaces flood storage volume. The Department also recognizes that some structures, such as garages, sheds and other buildings that are not dry flood-proofed are not likely to prevent the entry of floodwaters, and, therefore, the space within the walls of such a structure may not actually displace flood storage volume.

(c) The Department shall issue an individual permit for a regulated activity (or combination of regulated activities) in a flood fringe only if one of the following is satisfied:

1. The regulated activity is not subject to the flood storage volume displacement limits of this section, in accordance with (d) below;

2. The regulated activity will displace no flood storage volume onsite, as calculated for both the volume between the flood hazard area design flood and the 10-year flood, and the volume between the 10-year flood and the ground, in accordance with (e) below; or

3. The regulated activity will displace no more than 20 percent of the flood storage volume onsite, as calculated for both the volume between the flood hazard area design flood and the 10-year flood, and the volume between the 10-year flood and the ground, and all flood storage displacement onsite will be compensated offsite as follows:

i. If the regulated activity is located within the Central Passaic Basin, the requirements at (g) below shall be met;

ii. If the regulated activity is a major Highlands development, as defined at N.J.A.C. 7:38-1.4, the requirements at (h) below shall be met; or

iii. If the regulated activity is not located within the Central Passaic Basin and is not a major Highlands development, the requirements at (i) below shall be met.

(d) The following regulated activities (or combination of regulated activities) are not subject to the flood storage volume displacement limits of this section, provided the activity is not associated with a major Highlands development:

1. Any activity located in a tidal flood hazard area;

2. Any activity that displaces no more than five cubic yards of flood storage volume;

3. The reconstruction, enlargement, or other improvement of a lawfully existing railroad, public roadway, or driveway that serves only one single-family home or duplex, provided flood storage volume displacement is minimized;

4. The construction of a new driveway across a regulated water provided:

i. The driveway serves only one single-family home or duplex, which is not being constructed as part of a larger residential subdivision or multi-unit development;

ii. The lot on which the single-family home or duplex is being constructed was not created or subdivided after November 5, 2007;

iii. The applicant demonstrates that there is developable land onsite that cannot feasibly be accessed without crossing the water, including accessing the site through neighboring properties; and

iv. Any flood storage volume displacement resulting from the driveway is minimized;

5. The construction, reconstruction, relocation, elevation, or enlargement of one single-family home or duplex provided:

i. The single-family home or duplex is not being constructed as part of a residential subdivision or multi-unit development;

ii. The lot on which the single-family home or duplex is being constructed was not created or subdivided after November 5, 2007;

iii. Any enclosed area beneath the flood hazard area design flood elevation meets the requirements of N.J.A.C. 7:13-12.5(p); and

iv. Except for the construction of a driveway across a regulated water, which meets the requirements of (d)4 above, the site is not graded to accommodate the construction of the single-family home or duplex in such a way that flood storage volume would be displaced;

6. The construction or maintenance of a flood control project, which meets the requirements of N.J.A.C. 7:13-12.12, provided flood storage volume displacement is minimized;

7. The restoration of a regulated water to a natural condition that meets the requirements of N.J.A.C. 7:13-12.14(d), provided lost or displaced flood storage volume is minimized;

8. The depositing of sediment removed from a channel, which meets the requirements of N.J.A.C. 7:13-12.15(f);

9. The repair, modification, or reconstruction of a malfunctioning individual subsurface sewage disposal system, provided:

i. The need for repair or modification is not directly or indirectly caused by an expansion of the facility the individual subsurface sewage disposal system serves, or by a change in its use, including a change from disuse or abandonment to any type of use;

ii. Any repair or modification of the system is limited to serve only those volumes of sanitary sewage, estimated in accordance with N.J.A.C. 7:9A-7.4, that were approved prior to the malfunction;

iii. The applicant demonstrates that the volume of flood storage displacement is the minimum necessary to comply with the Department's Standards for Individual Subsurface Sewage Disposal Systems at N.J.A.C. 7:9A;

iv. All flood storage displacement is compensated for, either onsite or offsite, to the maximum extent practicable and in accordance with the methods set forth in this section; and

v. After all feasible flood storage compensation is provided, the project does not displace more than 20 percent of the flood storage volume existing at the time of application;

10. Investigation, cleanup, or removal of hazardous substances, provided:

i. The applicant demonstrates that the volume of flood storage displacement is the minimum necessary to comply with the Department's Technical Requirements for Site Remediation, N.J.A.C. 7:26E, and the Administrative Requirements for the Remediation of Contaminated Sites rules, N.J.A.C. 7:26C;

ii. All flood storage displacement is compensated for, either onsite or offsite, to the maximum extent practicable, and in accordance with the methods set forth in this section; and

iii. After all feasible flood storage compensation is provided, the project does not displace more than 20 percent of the flood storage volume existing at the time of application; and

11. Landfill closure activities authorized under a solid waste landfill closure and post-closure plan or disruption approval issued by the Department pursuant to N.J.A.C. 7:26-2A.8 or 2A.9, provided:

i. The applicant demonstrates that the volume of flood storage displacement is the minimum necessary to properly close the landfill and to properly maintain and monitor it after closure;

ii. All flood storage displacement is compensated for, either onsite or offsite, to the maximum extent practicable, and in accordance with the methods set forth in this section; and

iii. After all feasible flood storage compensation is provided, the project does not displace more than 20 percent of the flood storage volume existing at the time of application.

(e) The following shall apply to any regulated activity that is designed to displace no flood storage volume in accordance with (c)2 above:

1. The existing flood storage volume onsite (V[E]) is the volume of floodwater that is able to occupy the flood fringe onsite before the proposed regulated activity is undertaken. To determine the existing flood storage volume, calculate the volume of space within the flood fringe between the flood elevation and the ground surface as it exists on the date of application to the Department, and subtract the volume occupied by any structures that lawfully exist as of that date.

2. The proposed flood storage volume onsite (V[P]) is the volume of floodwater that will be able to occupy the flood fringe onsite once all proposed construction, excavation, filling and grading is completed. To determine the proposed flood storage volume, calculate the volume of space within the flood fringe between the flood elevation and the proposed ground surface, and subtract the volume occupied by any structures that will lawfully exist once all proposed construction is completed.

3. The proposed flood storage volume onsite (V[P]) shall be greater than or equal to the existing flood storage volume onsite (V[E]), for both the volume between the flood hazard area design flood and the 10-year flood, and the volume between the 10-year flood and the ground. Certain considerations should be made in calculating both (V[P]) and (V[E]), as set forth in (j) below. Additional flood storage volume can also be created onsite to compensate for proposed flood storage displacement in accordance with (m) below.

(f) Table 11.4 below sets forth the percentage of flood storage volume that a regulated activity (or combination of activities) can lawfully displace in various geographic areas of New Jersey. As described in further detail in this section below, a project cannot displace more than 20 percent of the flood storage volume that originally existed onsite, and all proposed displacement onsite must ultimately be compensated offsite. Table 11.4 indicates the dates from which the original and proposed flood storage volumes should be calculated for different geographic areas. Flood storage calculations shall be performed for both the volume between the flood hazard area design flood and the 10-year flood, and the volume between the 10-year flood and the ground, as described at (j) below, to show that the 20-percent and zero-percent limitations are met for both of these areas.

Table 11.4

ALLOWABLE PERCENTAGES OF FLOOD STORAGE VOLUME DISPLACEMENT

(Which shall be met for both the volume between the flood hazard area design flood and the 10-year flood, and the volume between the 10-year flood and the ground)

Geographic Area	Maximum onsite percentage of flood storage volume that a project can lawfully displace (P##)	Maximum total percentage of flood storage volume that a project can lawfully displace including all offsite credits (P##)
Central Passaic Basin	20 percent of flood storage that existed onsite on March 25, 1977	0 percent of flood storage that existed onsite on March 25, 1977
Highlands Preservation Area	20 percent of flood storage that existed onsite on January 31,	0 percent of flood storage that existed onsite on August 10,
1980	2004
Remainder of State	20 percent of flood storage that existed onsite on January 31, 1980	0 percent of flood storage that existed onsite on November 5, 2007

If associated with major Highlands development, as defined at N.J.A.C. 7:38-1.4.

(g) The following shall apply to any project located within the Central Passaic Basin that does not meet the requirements of (d) or (e) above:

1. The onsite percentage of flood storage volume that a project displaces shall be determined as follows:

i. Calculate the base flood storage volume onsite on March 25, 1977 (V[1977]) according to (j) and (k) below;

ii. Calculate the proposed flood storage volume onsite (V[P]) according to (j) and (l) below; and

iii. Calculate the percentage of flood storage volume displaced onsite (P[ONSITE]) as follows:

P[ONSITE] = (V[1977] - V[P])/V[1977]

2. The total percentage of flood storage volume that a project displaces, including any offsite compensation, shall be determined as follows:

i. Calculate any offsite compensation (V[C]) according to (o) below; and

ii. Calculate the total percentage of flood storage volume displaced (P[TOTAL]) as follows:

P[TOTAL] = (V[1977] - V[P] - V[C])/V[1977]

(h) The following shall apply to any major Highlands development within the Highlands Preservation Area that does not meet the requirements of (d) or (e) above:

1. The onsite percentage of flood storage volume that a project displaces shall be determined as follows:

i. Calculate the base flood storage volume onsite on January 31, 1980 (V[1980]) according to (j) and (k) below;

ii. Calculate the proposed flood storage volume onsite (V[P]) according to (j) and (l) below; and

iii. Calculate the percentage of flood storage volume displaced onsite (P[ONSITE]) as follows:

P[ONSITE] = (V[1980] - V[P])/V[1980]

2. The total percentage of flood storage volume that a project displaces, including any offsite compensation, shall be determined as follows:

i. Calculate the base flood storage volume onsite on August 10, 2004 (V[2004]) according to (j) and (k) below;

ii. Calculate any offsite compensation (V[C]) according to (o) below; and

iii. Calculate the total percentage of flood storage volume displaced (P[TOTAL]) as follows:

P[TOTAL] = (V[2004] - V[P] - V[C])/V[2004]

(i) The following shall apply to any project located outside the Central Passaic Basin (except for major Highlands development as described at (h) above) that does not meet the requirements of (d) or (e) above:

1. The onsite percentage of flood storage volume that a project displaces shall be determined as follows:

i. Calculate the base flood storage volume onsite on January 31, 1980 (V[1980]) according to (j) and (k) below;

ii. Calculate the proposed flood storage volume onsite (V[P]) according to (j) and (l) below; and

iii. Calculate the percentage of flood storage volume displaced onsite (P[ONSITE]) as follows:

P[ONSITE] = (V[1980] - V[P])/V[1980]

2. The total percentage of flood storage volume that a project displaces, including any offsite compensation, shall be determined as follows:

i. Calculate the base flood storage volume onsite on November 5, 2007 (V[2007]) according to (j) and (k) below;

ii. Calculate any offsite compensation (V[C]) according to (o) below; and

iii. Calculate the total percentage of flood storage volume displaced (P[TOTAL]) as follows:

P[TOTAL] = (V[2007] - V[P] - V[C])/V[2007]

(j) The following factors shall be considered when calculating flood storage volumes under this section:

1. A flood fringe is a dynamic system in which floodwaters flow into and out of a given area during the course of a flood event. Therefore, in order to effectively compensate for flood storage displacement caused by construction activities, compensatory flood storage created under this section must be designed to remain open to flow, such that floodwaters can freely enter and exit the area during the entire flood event. Examples of ineffective flood storage include:

i. The creation of belowground pipes or chambers connected to the flood hazard area by pipes, which fill with floodwaters at the onset of flooding and generally remain full until the flood recedes; and

ii. The creation of isolated depressions or other similar aboveground areas on the edge of a flood fringe, unless the area is connected to the flood hazard area with open channels or pipes of sufficient hydraulic capacity to allow floodwaters to freely enter and exit the area, and to rise and fall at the same elevation as the flood event.

2. The flood storage displacement limits in this section apply to both the volume between the flood hazard area design flood and the 10-year flood, and the volume between the 10-year flood and the ground. As such, applicants must demonstrate that a proposed project meets these limits for both floods unless the entire project lies above the 10-year flood elevation.

3. Except as provided in (j)4 below, flood storage displacement proposed above the 10-year flood elevation onsite must be compensated for by the creation of flood storage above the 10-year flood elevation. Similarly, flood storage displacement proposed below the 10-year flood elevation onsite must be compensated for by the creation of flood storage below the 10-year flood elevation. This applies whether the compensation occurs onsite, as described at (m) below, or offsite, as described at (o) below.

4. In cases where a site lies predominately below the 10-year flood elevation and it is demonstrated that it is not possible to compensate onsite for all flood storage displacement proposed above the 10-year flood elevation, the applicant shall pursue the following options in the order listed below:

i. The applicant shall create onsite flood storage volume above the 10-year flood elevation, in accordance with (m) below, to the maximum extent practicable;

ii. If the applicant cannot fully compensate onsite for all flood storage displacement under (j)4i above, offsite flood storage volume shall be created above the 10-year flood elevation in accordance with (o) below to the maximum extent practicable; and

iii. If the applicant cannot fully compensate for flood storage displacement under either (j)4i and ii above, flood storage volume shall be created below the 10-year flood elevation, either onsite or offsite, for all flood storage displacement that is unable to be created in accordance with (j)4i and ii above.

5. In cases where the 10-year flood elevation is not provided on State or Federal flood maps, calculations can instead be performed using a flood depth halfway between the flood hazard area design flood elevation and the lowest ground elevation within the flood fringe onsite. For example, at a given cross-section through a site, if the flood hazard area design flood elevation is 90.0 feet NGVD and the lowest ground elevation within the flood fringe is 80.0 feet NGVD, flood storage calculations can be performed at that cross-section using a flood elevation of 85.0 feet NGVD at that location, if the 10-year flood elevation is unknown. Furthermore, this halfway depth must be determined separately for each cross-section in the flood fringe, and at close intervals throughout the site in order to provide an accurate estimate of the upper and lower flood storage volumes.

6. The volume inside a stormwater management basin or other impoundment is considered displaced flood storage volume. For instance, when calculating the flood storage volume onsite during the 10-year flood, the volume below the 10-year water surface elevation in the basin is considered displaced flood storage volume.

7. The volume behind a dike, levy or similar barrier that prevents the free flow of water is considered displaced flood storage volume.

8. The volume inside a building is considered displaced flood storage volume except for the space inside an enclosure below the lowest floor of a building that conforms to the requirements at N.J.A.C. 7:13-12.5(p).

9. The construction of a channel modification, or the reconstruction of a water control structure such as a bridge or culvert, can result in lower flood elevations at some point along the water. In such a case, the volume in the flood fringe between the existing and proposed flood elevations is considered displaced flood storage volume.

(k) The base flood storage volume onsite (V##, V##, V##, and/or V##) is the volume of floodwater that was able to occupy the flood fringe onsite on the appropriate date shown in Table 11.4 depending on the geographic location of the project. To determine the base flood storage volume, calculate the volume of space within the flood fringe between the flood elevation and the ground surface as it existed on the appropriate date in Table 11.4, and subtract the volume occupied by any structures that lawfully existed on that date.

(l) The proposed flood storage volume onsite (V[P]) is the volume of floodwater that will be able to occupy the flood fringe onsite once all proposed construction, excavation, filling and grading is completed. To determine the proposed flood storage volume, calculate the volume of space within the flood fringe between the flood elevation and the proposed ground surface, and subtract the volume occupied by any structures that will lawfully exist once all proposed construction is completed.

(m) Additional flood storage volume may be created onsite to compensate for proposed flood storage displacement only on land that meets the requirements of (n) below and in one or both of the following ways:

1. Removing material that has been previously lawfully placed within the flood fringe, such as fill or structures, and properly disposing the material outside a flood hazard area, as described in (q) below; or

2. Excavating material from below the surface of the ground and properly disposing the material outside a flood hazard area, as described in (r) below.

(n) Flood storage volume may be created onsite to compensate for regulated activities that displace flood storage as described in (m) above provided the onsite compensation:

1. Is created within or adjacent to the flood hazard area of the same water as the proposed flood storage displacement, or a tributary to the same water as the proposed flood storage displacement, provided the tributary lies upstream of the site or the flood hazard area of both waters connect onsite;

2. Is not created in a floodway;

3. Is not created within either of the following areas, unless the area where the compensation will be created has been subject to previous, lawful disturbance:

i. Within a riparian zone, pursuant to N.J.A.C. 7:13-4.1 and 11.2; or

ii. Within 300 feet of a Highlands open water, if the project is a major Highlands development as defined in the Highlands Water Protection and Planning Act rules at N.J.A.C. 7:38-1.4; and

4. Would not have other significant adverse environmental consequences; the proposed compensation shall not merely substitute the adverse effects of the proposed activities with adverse impacts upon threatened or endangered species, aquatic biota, fishery resources or Highlands resource areas.

(o) Offsite compensation (V##) is additional flood storage volume created offsite to compensate for proposed flood storage displacement onsite. Offsite compensation can be created only on land that meets the requirements of (p) below and only in one or more of the following ways:

2. Excavating material from below the surface of the ground and properly disposing the material outside a flood hazard area, as described in (r) below; or

3. Purchasing fill credits, where available, if the project is located in the Central Passaic Basin, as described in (s) and (t) below.

(p) Flood storage volume can be created offsite to compensate for regulated activities that displace flood storage as described in (o) above provided the offsite compensation:

2. Is not separated from the proposed flood storage displacement by a water control structure, such as a bridge, culvert or dam, unless the applicant demonstrates that the water control structure causes no significant change in the flood hazard area design flood elevation;

3. Is situated within the same HUC-14 watershed as the proposed flood storage displacement;

4. Is not created in a floodway;

5. Is not created within either of the following areas, unless the area where the compensation will be created has been subject to previous, lawful disturbance:

i. Within a riparian zone, pursuant to N.J.A.C. 7:13-4.1 and 11.2; or

ii. Within 300 feet of a Highlands open water, if the project is a major Highlands development as defined in the Highlands Water Protection and Planning Act rules at N.J.A.C. 7:38-1.4;

6. Would not have other significant adverse environmental consequences; the proposed compensation shall not merely substitute the adverse effects of the proposed activities with adverse impacts upon threatened or endangered species, aquatic biota, fishery resources or Highlands resource areas;

7. Is agreed to in writing by the owners of the land on which the offsite compensation is proposed; and

8. Is proposed on land which, subsequent to the creation of the offsite compensation, is deed restricted against future flood storage volume displacement. The modified deed shall be filed with the local county clerk, a copy of which shall be provided to the Department within 90 calendar days of the issuance of the individual permit.

(q) For the purposes of (m)1 and (o)1 above, flood storage volume can be created by removing material previously placed within the flood fringe, such as fill or structures, provided:

1. The material to be removed was not placed in violation of this chapter;

2. The material to be removed is not associated with an activity permitted-by-rule under N.J.A.C. 7:13-6;

3. The area disturbed by the removal of the material is properly graded so that floodwaters can freely enter and exit;

4. The material to be removed is properly disposed of outside of any regulated area; and

5. The removal of the material is approved under an individual permit and is completed concurrent with or prior to the commencement of the activities for which the compensation is intended.

(r) For the purposes of (m)2 and (o)2 above, flood storage volume can be created by excavating material from below the surface of the ground, provided:

1. The excavation is located in a flood fringe, or is located adjacent and connected to a flood hazard area so that floodwaters can enter the excavated area;

2. The excavation is located below the flood hazard area design flood elevation;

3. The excavation is located above the seasonal high water table;

4. The excavation is located above the normal water surface elevation of the nearest regulated water;

5. The area disturbed by the excavation is properly graded so that floodwaters can freely enter and exit;

6. The excavated material is properly disposed of outside of any regulated area; and

7. The excavation is approved under an individual permit and is completed concurrent with or prior to the commencement of the activities for which the compensation is intended.

(s) For the purposes of (o)3 above, offsite compensation in the Central Passaic Basin can be accomplished in certain cases described in (t) below through the purchase of fill credits. A fill credit is a unit of flood storage volume that has been created in the Central Passaic Basin by excavation and/or removal of fill, and which can be sold to a permittee to compensate for proposed fill elsewhere in the Central Passaic Basin. The Department has previously permitted several facilities to create fill credits. However, no person or facility shall create new or additional fill credits in this manner. A person or facility shall furthermore buy or sell a fill credit only if it has been lawfully created under a permit previously approved by the Department as noted above. Once all previously approved fill credits have been purchased, offsite compensation in the Central Passaic Basin will no longer be possible through fill credits.

(t) For the purposes of (o)3 above, offsite compensation in the Central Passaic Basin can be made through the purchase of fill credits, as described in (s) above, provided the following requirements are satisfied:

1. The fill credits are purchased from a person or facility that has been authorized by the Department to create and sell fill credits in accordance with (s) above;

2. The flood storage volume on which the fill credits are based was created prior to the submittal of the application for the activities for which compensation is required;

3. The Department approves the use of the particular fill credits for the particular activity; and

4. The applicant provides the Department with adequate documentation of the purchase of the fill credits.

(u) If the percentage of flood storage volume displacement on a site already exceeds a limit at Table 11.4 above due to activities that were previously undertaken in accordance with this chapter, the Department shall issue an individual permit for a new regulated activity on the site only if an equal amount of flood storage volume is created to compensate onsite for any displaced flood storage volume that would result from the new regulated activity, in accordance with (e) above. Compensatory flood storage volume shall not be created offsite in such a case, and shall only be created onsite, as described in (m) above. The volume of fill in excess of the limits in Table 11.4 does not need to be removed from the site.

(v) If the percentage of flood storage volume displacement on a site already exceeds a limit at Table 11.4 above due to activities that were previously undertaken in violation of this chapter, the Department shall issue an individual permit for a new regulated activity on the site only if the following requirements are satisfied:

1. The applicant either obtains an individual permit for the activities undertaken in violation of this chapter, or else removes from the flood hazard area any fill or structure that was placed in violation of this chapter;

2. All displaced flood storage volume in excess of the limit in Table 11.4 is restored onsite; and

3. An equal amount of flood storage volume is created to compensate onsite for any displaced flood storage volume that would result from the new regulated activity, in accordance with (e) above. Compensatory flood storage volume shall not be created offsite in such a case, and shall only be created onsite, as described in (m) above.

(w) If the Department issues or has issued an individual permit for a regulated activity that displaces flood storage volume on a site, and that activity was subject to a flood storage displacement limit at the time the permit was issued, subsequent subdivision of that site shall not increase the total amount of flood storage volume that can be displaced on the site under future applications. Instead, the following shall apply:

1. Flood storage volume can be displaced within a portion of the subdivided site only to the extent that the total flood storage volume displaced within the entire subdivided site does not exceed the flood storage displacement limits of this section;

2. If the subdivided site involves multiple lots owned (or to be owned) by different persons, any remaining allowable flood storage volume shall be divided equally among all lots in the flood fringe, unless the owners of all lots in the flood fringe otherwise agree in writing; and

3. The volume of flood storage displacement permissible on each lot shall be described in any individual permit issued for the site as well as in the deed of record for each affected property. The modified deed shall be filed with the applicable county clerk, a copy of which shall be provided to the Department within 90 calendar days of the issuance of the individual permit.

N.J. Admin. Code § 7:13-11.4

Amended and recodified from 7:13-10.4 by 48 N.J.R. 1067(a), effective 6/20/2016