TOWNSHIP OF WASHINGTON—A professional engineer from Emerson — who previously questioned the use of LIDAR data to determine whether an unnamed tributary to the Musquapsink Brook is a regulated waterway — told Pascack Press that the calculations used by Boswell Engineering to keep certain areas out of its drainage basin were “based on a technicality.”
“The developer’s engineer basically kept areas out of the drainage area calculations based on a technicality that pipes in the existing (Northgate) development were not sized for a 100-year storm. Pipes in New Jersey not being sized for a 100-year storm should be a source of shame. It is the reason downtowns flooded during (remnants of Hurricane) Ida and streets poured down driveways into homes,” said Carol Hoernlein, a private professional engineer who had criticized a prior basin calculation that appeared to leave off a large tract of Northgate land.
She added, “In the rest of the world and at the USGS, a drainage area is a drainage area. The water that falls as rain in that area flows to the same spot, culvert, or creek by gravity. But now we know how the incredible shrinking drainage area for this one proposed development occurred and exactly why the method chosen was not based on USGS Streamstats data.”
Hoernlein charged, “NJDEP allowed the designation of a drainage area to be shrunken simply based on rate of conveyance in pipes from an existing development and not the geography. This is a very bad precedent to set if New Jersey has any hope of clean water and protection from climate change.”
She also told Pascack Press that based on its drainage to the Musquapsink Brook, which is classified as a NT-C1 (non-trout production, Category One) waterway, it was likely that the unnamed tributary was a Category One waterway.
If the waterway is declared a regulated or Category One waterway, it’s likely any potential development at 660-682 Pascack Road would need to follow NJDEP rules for water quality protection, possibly including buffers, and implement stricter stormwater quality and quantity measures.
A Meisten Street neighbor has also voiced doubts about Boswell’s April 17 oral report that found the basin was not a regulated waterway. However, a prior Pascack Press review of NJDEP Category One waterways posted online revealed that tributaries to the Oradell Reservoir, a source of drinking water for hundreds of thousands of Bergen and Passaic county residents, are considered Category One, or protected waterways.
The unnamed tributary behind the proposed strip mall joins up with the Musquapsink Brook, enters Schlegel Lake, and joins Pascack Brook as it heads towards the Oradell Reservoir. Boswell did not mention water supply, or the Oradell Reservoir, in his oral report to council on April 17.
(See “Do Mall Applicant’s Drainage Basin Calculations Hold Water?”, Michael Olohan, March 12, 2023, Pascack Press.)
“I listened to Mr. Boswell’s presentation on drainage area and LIDAR (data) precision, but the gentlemen who spoke after Mike Agnello (Councilman Tom Sears and resident James Walsh, Burke Street) had very good points. Areas were left out that should have been included. I don’t agree with Mr. Boswell when he spoke about the 100-year storm as an excuse to remove such a large area from the drainage area maps,” Hoernlein told Pascack Press April 25.
LIDAR (Light Detection and Ranging) data is gathered from aerial sources (drones, planes, and helicopters) that works on the principle of radar, but uses light from a laser. The laser bounces back off ground elevations to provide an accurate measure of ground contours and elevations, helping to outline the areas draining into a waterway or waterway segment.
James Walsh of Burke Street also questioned why certain drainage areas at the end of Burke Street were excluded from Boswell basin maps. Walsh said the areas excluded “could easily put you over the 50 acres.”
However, Boswell said if the storm drain outlets are not designed for 100-year storms, they are not included in the drainage area. Walsh insisted the topography indicated the area drained to the unnamed tributary. Boswell said the DEP manual said they should be excluded.
Sears wondered who entered the LIDAR data into the computers to arrive at the basin calculations and also why three different engineers arrived at three different conclusions about the tributary’s drainage basin size. He said the engineers’ conclusions offered “multiple confusions” about what the basin’s estimated size was and what happened to a previously designated Category One waterway.
“I was encouraged by the (council’s) questions and their concern and respect for the residents who spoke. They seem to understand the issues at stake here. I was concerned though, that the (Township) Engineer often tries in other towns to advocate to get NJDEP regulated waters unregulated,” Hoernlein said via email.
In addition to Hoernlein, 667 Meisten St. resident Michael Agnello continues to voice his opposition to the tributary’s non-regulated status. He said he had repeatedly been told that the waterway behind his house is a Category One waterway, required protection, and was protected by a property easement on his land for nearly 50 years.
Recently, without explanation, the unnamed tributary was also left off of Boswell Engineering’s February 2023 study of conditions in the Musquapsink Brook, titled Musquapsink Brook Condition Assessment, although the study named two other “unnamed” tributaries to the brook, and lists both as Category One waterways. (Pascack Press requested a copy of the report after seeing it mentioned on a recent Bills List.)
At the April 17 Township Council meeting, Boswell said the process for determining the drainage area of a flood hazard area was outlined in the state DEP’s technical manual section 2.1.3.
He said he “paraphrased” one section of the technical manual, noting drainage areas that drain storm runoff that are not designed for 100-year storms are not included in a drainage area measurement.
Boswell said the drainage basin mapping produced by LIDAR data was mapped at one-foot contours, and much “more precise” than the U.S. Geologic Service Streamstats data, which was used by Emerson engineer Carol Hoernlein, and quoted by a resident, to dispute prior basin calculations used to determine the waterway was not regulated.
Boswell previously agreed with Michael Agnello of 667 Meisten St., who said the USGS Streamstats data put the drainage basin at 58.8 acres. However, Boswell then noted that the LIDAR data that Boswell reviewed showed that the basin was only 48.832 acres.
Agnello has questioned what happened to the 10 acres’ difference between USGS Streamstats and the Najarian Associates and Boswell basin determinations. Boswell said the difference was due to the LIDAR data’s “more precise” one-foot contour elevations versus the 10-foot contour elevations used to calculate the USGS Streamstats basin data.
The prior determination of 48.2 acres was calculated in 2019 by Najarian Associates, Eatontown, which was disputed by Agnello. In January 2020, NJDEP, using Najarian’s 48.2 acre calculation, declared the unnamed tributary behind his home as a non-regulated waterway under the state’s Flood Hazard Area Act rules.
Moreover, the 2020 NJDEP decision was based on a proposal from 660 Pascack Realty LLC for a 137-vehicle commuter parking lot on four of five lots at 660-682 Pascack Road, not a 17,100-square-foot shopping plaza. In 2019, NJDEP had asked Bertin Engineering, the applicant engineer, to provide a “compelling public need” why they needed to construct a parking lot at 660-682 Pascack Road.
The reason was to “demonstrate that this location within the riparian zone is the only practicable location.” wrote an NJDEP environmental specialist then. It was not clear what “compelling need” was offered in response or why the parking lot was never built.
Boswell said on April 17 that the LIDAR data was independently reviewed by Boswell engineers who came up with the basin calculation that was below 50 acres. He said he was “very confident” in the drainage basin acreage calculation.
Hoernlein told us, “It’s a distraction if they’re excluding a particular area based on pipe capacity. An area that belonged to an existing development being excluded because of the (storm outlet) pipe capacity is weird. I’ve never changed a drainage area because of a storm drain’s pipe capacity.”
Hoernlein noted that the 2018 Flood Hazard Area Control Act Technical Manual, cited by Boswell in his review, did not appear to exclude stormwater pipes that may handle less than a 100-year storm.
Pascack Press found the NJDEP FHACA Technical Manual online and the section that Boswell quoted from. Another technical manual section defined how NJDEP defines a drainage area.
“Drainage area is defined in the (Flood Hazard Area Control Act) Rules as the “geographic area within which water, sediments and dissolved materials drain to a particular receiving waterbody or to a particular point along a receiving waterbody.” The term drainage area is generally synonymous with watershed in the sense that it describes the area of land from which a feature collects stormwater runoff,” notes the Technical Manual Flood Hazard Area Control Act Rules, N.J.A.C. 7:13.
“If a parcel is said to be located within the drainage area or watershed of a particular stream, stormwater runoff from that parcel will eventually reach that stream either through overland flow (flow across the surface of the ground or in streams) or via stormwater pipes. Groundwater flow is not considered to be part of a feature’s drainage area. Drainage area is measured in acres or square miles and is a good indication of the relative size of a feature and its potential to cause flood damage. As the drainage area of a water increases, it will receive and ultimately convey more runoff,” states p. 15 of the manual under Section 2.1.3, Determining Drainage Area.
The 347-page NJDEP 2018 technical manual is here.
Neighbors to the tributary, which runs behind their Meisten Street homes and behind a 2.4-acre property at 660–682 Pascack Road proposed for a neighborhood retail plaza, assert that the drainage basin calculations used were incorrect and that the stream should still be classified as a Category 1 or C1 waterway, and protected from runoff and development.
It was previously classified as a C1 tributary due to its significance as a water supply source to the reservoir.
(See “Follow the water on strip mall application,” Michael Olohan, Feb. 27, 2023.)