COMPREHENSIVE ENVIRONMENTAL INCORPORATED

COMPREHENSIVE

ENVIRONMENTAL

INCORPORATED

www.ceiengineers.com

August 6, 2020

Jennifer Miller, Conservation Agent

Seekonk Conservation Commission

100 Peck Street

Seekonk, MA 02771

Re: 33 Lake Street – Costa Development

Notice of Intent – Third Party Review

Dear Ms. Miller:

As requested by the Seekonk Conservation Commission, CEI has conducted a technical review of

the Notice of Intent (NOI) submitted under the Massachusetts Wetlands Protection Act (WPA)

and Town of Seekonk Wetlands Protection Bylaw for the proposed development located at 33

Lake Street, Seekonk MA 02771.

CEI has based the review on the following information provided as part of the NOI application:

1. Notice of Intent package dated 04/29/20 by InSite Engineering Services (InSite).

2. “Costa Office Building” Plans, dated 02/24/20, revised 06/03/20, by InSite.

3. “Operations and Maintenance Plan”, undated, by InSite.

4. Stormwater Management Narrative, dated 02/24/20 by InSite.

CEI staff conducted a site visit on July 24, 2020 to review site conditions. CEI’s scope of work for

the review included field review of the wetland delineation. CEI offers the following comments

based on the site visit and our review of the NOI information listed above.

I. Compliance with Stormwater Management Standards

Based on our review of the information provided, and assuming that all of the following

comments are satisfactorily resolved, CEI believes the project design addresses the

Massachusetts Stormwater Standards as follows:

Standard 1. No new untreated stormwater discharges

The project watershed includes a subcatchment area “Post-Uncontrolled” that does not

receive runoff from impervious surface but may pose nutrient and pesticide risks. See

comment IV.A.1 for compliance concerns. Provided the applicant addresses the issues

presented in the aforementioned comment, Standard 1 is met.

Ms. Jennifer Miller

August 6, 2020

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Standard 2. Peak rate control

While peak rate control appears to have been met for Parcel 1, the proposed grading

changes at the parcel border and existing ground clearing within Parcel 2 indicates that the

Applicant has not provided enough information to confirm peak rate control for all

disturbed areas. Standard 2 is not met.

Standard 3. Groundwater Recharge

Standard 3 is met for Parcel 1.

Standard 4. Water Quality

a. Water Quality Volume Calculations

Provided the square footage of the roof is included in the 0.352 acres of post-construction

impervious surface, Standard 4 WQV is met.

b. TSS Removal

While the Applicant provided a table in the narrative representing TSS removal

efficiencies, CEI recommends the inclusion of standard TSS removal worksheets and

proprietary oil/water separator info, as discussed in comment V.4.

Standard 5. Land Uses with Higher Potential Pollutant Loads (LUHPPL)

The site is not a LUHHPL, Standard 5 is not applicable.

Standard 6. Critical Areas

The proposed site is not within a critical area, Standard 6 is not applicable.

Standard 7. Redevelopment

The Applicant indicated on the Stormwater Checklist that this is a redevelopment project.

However, the proposed project does not qualify as redevelopment for the following criteria:

1. There is a net increase in impervious area from pre to post development.

2. Portions of the proposed project require tree removal and disturbance of

undeveloped land.

Ms. Jennifer Miller

August 6, 2020

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Standard 8. Construction Phase Erosion and Sediment Controls

The provided plan set and narrative do not indicate where soil stockpiling will occur. CEI

recommends all stockpiling occur outside of the 100-foot wetland buffer zone and

additional erosion control measures be provided, i.e. silt fences.

Standard 9. Operation and Maintenance

Standard 9 is met, provided the Applicant include proprietary oil/water separator

manufacturer’s materials (comment V.4) and addresses the concerns detailed in comment

IV.A.1.

Standard 10. Prohibition of Illicit Discharges

Standard 10 is met.

II. Site Visit

1. Upon arrival at the site, CEI observed Parcel 2, indicated on the “Existing Conditions” plan,

was completely cleared and surrounded with erosion controls in the form of hay bales.

Additionally, four (4) test pits are indicated in this area in plan set drawings, but no test pit

data was provided. CEI recommends that the Applicant provide additional details in the

narrative and plan set drawings that address the purpose of this clearing and the proposed use

of Parcel 2. Additional drawings in the plan set do not show Parcel 2 incorporated in proposed

conditions. Issues identified surrounding Parcel 2 include:

a. Disturbed erosion controls. Images 1 and 2 (following page) show the

observed breaks at the southern edge of the parcel, within 25 feet of the

wetland. Erosion control maintenance is required.

b. Potential wetland disturbances. Image 3 below shows a tree that had been

previously removed, potentially during the clearing of Parcel 2. CEI

observed a wetland flag on the removed tree that matched the color and

material of remaining wetland flags on-site (Image 4). Writing on the flag

had been washed off, but remnants of black sharpie were evident.

Additionally, jurisdictional wetland areas should be clearly flagged (or

reflagged) prior to any work.

Ms. Jennifer Miller

August 6, 2020

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Image 1. Hay bales Image 2. Hay bales

Image 3. Visible flag on downed tree Image 4. Intact wetland flag

Ms. Jennifer Miller

August 6, 2020

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2. It appears that there are a number of disturbed jurisdictional wetland areas on-site. Evidence

of material disposal exists along the roadway, with approximately 10 waste/gas vents visible

in sections of non-native mixed soil and apparent construction debris (see Images 5 and 6,

below). Additionally, wetland buffer areas south of erosion controls in Parcel 2 contained

debris that appeared to have been deteriorating for a substantial amount of time (see Image

7, next page). CEI recommends that the Commission assess the historical land use for this

site and determine if further development will be impacted by non-native, unstable fills. 310

CMR 10.08 1(f) prohibits development in areas that have been illegally filled throughout

historic land-use. Additionally, if these foreign materials are removed from the site, CEI

recommends that the Commission require disposal documentation to verify no additional

contamination will occur from disposal activities.

Image 6. Close-up of fill

and vent

Image 7. Debris on other

side of Parcel 2 hay bales.

Image 5. Visible vents

and non-native soils/fill

Ms. Jennifer Miller

August 6, 2020

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3. The Applicant describes the vegetation as “sparse” from Lake Street back to the 50-foot

buffer. CEI observed small tree and shrub vegetation that provided full canopy cover and

wildlife habitat from the street to the wetland line (Image 8).

III. Wetland Resource Area Impacts

A. 100 ft Buffer for Bordering Vegetated Wetlands (BVW)

1. No field data forms for determination of the wetland boundaries were provided.

2. Parcel 2 has been completely cleared and has construction equipment and stockpiles stored

within/near the 100-foot buffer with insufficient erosion controls, containment pads or spill

prevention (see Images 9 and 10, below).

Image 8. Wooded uplands between

street and wetlands on Parcel 1.

Ms. Jennifer Miller

August 6, 2020

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IV. Civil Site Design

1. The Applicant provided soil data only in a table on the “Detail and Soils” drawing in the plan

set. Standard Soil Boring Logs were not provided, and it appears that there was no town

designee present as a witness during said testing. There are eleven (11) test pits labeled on

the provided plan set, including those shown in Parcel 2, however only three (3) data points

were provided in the plan set. Furthermore, the “Deep Hole” numbers provided (TP1, TP2,

TP3) do not match the labels of any of the eleven (11) test pits indicated on the drawings

(TPD-1, TPD-2, TPD-3, TP2-4, TP2-3, TP2-2, TP2-1, TP8-2, TP8-1, TP8-3, TP8-4).

2. In the narrative, the Applicant states that the proposed use for the site includes a private well

and an on-site sanitary disposal system. No Title V information was provided, nor was the

proposed location of either structure indicated.

Image 9. Improper equipment storage Image 10. Stockpiles and cleared lot.

Slope of lot visible

Ms. Jennifer Miller

August 6, 2020

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3. The proposed grading appears to create a significant drop-off in slope near the proposed

infiltration basin, around the 25-foot buffer setback. Additionally, proposed grading contours

end at the boundary between Parcel 1 and Parcel 2, creating a steep area and changing the

amount of runoff and the path of flow across Parcel 2.

A. Planting and Landscaping Design

1. No planting and landscape plan was provided. CEI recommends that the Applicant

provide a detail and narrative to address the revegetation and stabilization necessitated

by the addition of fill upgradient and within 50 feet of wetlands, as well as a long-term

management plan in the O&M. To prevent contaminated runoff from entering wetlands,

CEI recommends that use of fertilizers and pesticides be restricted on the southern slope,

behind the building and parking area. Plant species should be detailed in the plan to

confirm that none are listed invasive or non-native species.

V. Stormwater Management Design

1. The invert provided in the HydroCAD calculations for catch basin “CB1” does not match

the invert labelling on the provided plan set. Additionally, the provided peak elevations in

CB1 for each storm event are assuming an empty sump and may not reflect real-time

conditions, i.e. sediment buildup during a large storm event.

2. CEI was only able to identify one (1) catch basin on the plan set provided. State guidance

recommends one (1) catch basin per ¼ acre of impervious area. As the provided HydroCAD

calculations state total impervious area for the site as “Paved parking”: 0.352 acres, CEI

recommends the proposed catch basin be designed as a double catch basin with a 6 ft

diameter.

3. Based on insufficient test pit data (see comment IV.1), CEI is unable to confirm that the

infiltration basin has sufficient separation to groundwater.

4. Portions of the narrative describe the use of an oil/water separator in CB1. If a proprietary

BMP is proposed, the manufacturer’s information should be provided in the O&M Manual.

Additionally, confirmation that the proprietary device is sized to accommodate on-site runoff

pollutant and TSS loads is required.

VI. Stormwater Management Calculations

1. It appears that the rooftop square footage was not reflected in HydroCAD calculations. CEI

recommends modeling impervious areas as “paved/parking” and “roof”, respectively.

2. No HydroCAD modeling was provided for the 25-year storm.

Ms. Jennifer Miller

August 6, 2020

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VII. Construction Phase Pollution Controls

1. Hay bales are not acceptable replacements for straw wattles, as they may contain invasive or

non-native seeds.

2. It appears that soil stockpiles will be required, perhaps following the excavation for the

building addition. The plan should describe the final destination of the stockpiled material.

If the stockpiled material will not be used onsite, the applicant should remove the material

without delay. Additionally, the plan should describe practices to stabilize temporary soil

stockpiles in more depth. If the practices do not provide for routine covering of soils

stockpiles with tarps, we recommend a condition of approval that, in the event the specified

practices do not adequately control wind and water-borne erosion of the stockpiles, the Town

may require the applicant to cover stockpiles at the end of each working day with properly

anchored tarps which should remain in place when the stockpiles are not being actively used.

3. The site requires a NPDES Construction General Permit, since it involves construction

activities disturbing greater than one acre. We recommend a condition of approval requiring

both the Applicant and its contractor to provide evidence, prior to beginning construction,

that each has filed a Notice of Intent with US EPA Region 1 under this permit. A copy of

the Stormwater Pollution Prevention Plan (SWPPP) required under this permit should also

be furnished to the Town.

If you have any questions or comments regarding this report, please contact Matt Lundsted or

Elisha Musgraves at 508-281-5160.

Sincerely,

COMPREHENSIVE ENVIRONMENTAL, INC.

Matt Lundsted, Principal

COMPREHENSIVE ENVIRONMENTAL INCORPORATED

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