Hydroworks HydroFilter Manual

Hydroworks®HydroFilter
Operations & Maintenance Manual
Version 1.0

1
Introduction
The HydroFilter is a stormwater management device designed to both treat and
infiltrate stormwater.
Standard filters just treat stormwater contaminants (metals, TSS, oil, nutrients) but do
nothing to maintain the hydrologic cycle during urbanization. Maintenance of the
hydrologic cycle helps prevent flooding, erosion and promotes water quality by
maintaining the stream geomorphology. Maintenance of the hydrologic cycle requires
infiltration to reduce the additional stormwater volume and reduction in infiltration that
occurs with standard development.
The requirement for infiltration is complicated by the fact that urbanization increases
pollution and it would be detrimental to the environment to merely infiltrate this
polluted water. Therefore, there is a need to pretreat the water that is to be infiltrated
from urbanized areas such as roads and parking lots. HydroFilter provides the
pretreatment and infiltration (recharge) in one device.
Many site infiltration practices try to infiltrate all the water and the low point of the site
just prior to connection with the municipal storm drain system. This is not the same as
predevelopment infiltration which is dispersed all over the site. Centralized infiltration
can be problematic since the storm sewer is too deep, requiring an outlet control
device to back up water upstream to get the required infiltration volume. Centralized
infiltration can cause groundwater mounding and sealing of pores reducing infiltration
capacity.
LID practices promote more infiltration at the source. HydroFilter can be considered
an LID practice since the intention is to promote dispersed infiltration around the site
at each inlet which is a more holistic approach to maintenance of the hydrologic
cycle.
As storm water treatment structures fill up with pollutants they become less and less
effective in removing new pollution. This is especially true of any stormwater
treatment practice that includes infiltration such as HydroFilter. Therefore, it is
important that storm water treatment structures be maintained on a regular basis to
ensure that they are operating at optimum performance. The HydroFilter is no
different in this regard and this manual has been assembled to provide the
owner/operator with the necessary information to inspect and coordinate
maintenance of their HydroFilter.
Hydroworks®HydroFilter Operation
The Hydroworks HydroFilter (HF) is a LID device since it promotes the maintenance of
the hydrologic cycle. Unlike many infiltration systems however, HydroFilter was
designed for dispersed infiltration around the site, such as inlets or catch basins.
Under normal or low flows, water enters the structure through a grate or inlet. Incoming
water builds up around the filters and creates head to drive water radially into the filter
cartridges from theoutside throughto the center of the cartridge. There is a 6” (150mm)

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diameter open center that runs through the center of each cartridge. Water reaching
the center opening falls by gravity into the base plug and is conveyed out of the
structure by a pipe(s) into the surrounding ground to be exfiltrated (Figure 1). A solid
cone with a check valve is placed on top of the top filter cartridge to prevent incoming
water from entering the 6” (150 mm) diameter opening while still allowing air to escape
from the center of the cartridges as water enters the filter.
Figure 1. Hydroworks HydroFilter Operation –Low Flow
The exfiltration pipes can be surrounded by crushed stone to increase the volume of
water to be exfiltrated back into the ground.
If the flow rate into the structure exceeds the flow capacity of the filter cartridges or
infiltration storage capacity around the infiltration pipes water will overflow into the
downstream storm drain.
It should be noted that the HydroFilter can come in many configurations (round or
square or rectangular structures) with one or two or more cartridges in a stack and

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one or more stacks per structure. Therefore, the configuration of the HydroFilter
varies depending of the flow rate to be treated and volume of water to be infiltrated.
Figure 2. Hydroworks HydroFilter Operation –Bypass

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Inspection
Procedure
The HydroFilter should be inspected 24 hours after rainfall. Inspection within 6 hours
of rainfall may not provide useful information regarding maintenance since the unit
may be draining down.
If the structure has not drained down to the base (bottom of lowest filter cartridge)
within 24 hours of the last rainfall, the HydroFilter likely requires maintenance.
In the event of standing water in the structure around the cartridges the cone should
be removed from a stack of cartridges. If standing water is visible in the central core
of the filter stack consistent with the level of water on the outside of the filter stack this
is indicative of a high ground water or slow infiltration and not required filter
maintenance.
However, if the water level in the central cartridge is below the bottom of the lowest
filter cartridge with standing water around the filter cartridges then filter maintenance
is required.
Frequency
Construction Period
The filter cartridges should not be installed in the HydroFilter during the construction
period since construction sediment will prematurely plug the cartridges requiring
excessive maintenance during the construction period. A plate is installed in the base
for the construction period to remind the contractor that the cartridges should only be
installed for post construction operation. This plate needs to be removed when the
cartridges are installed for post development operation.
Post-Construction Period
The Hydroworks HydroFilter should be inspected twice during the first year of
operation for normal stabilized sites (no exposed soil or materials storage). The initial
inspections will indicate the required future frequency of inspection and maintenance
if the unit was maintained and put into service (filters installed) after the construction
period.
It is anticipated that the filter cartridges will need to be replaced annually. However,
this will depend on pollutant loadings on the site and off-site activities (nearby
construction, etc.). Filters are different from separators in that sediment levels at the
bottom of a filter do not dictate maintenance frequency.

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A filter does not need to be maintained until it’s rated treatment rate decreases to the
point where it can no longer provide the required annual percentage of pollutant
removal. This is a hydraulic requirement that will depend on the hydrology (rainfall
intensity distribution) and characteristics of the site (imperviousness, area, pollutant
loading) being designed. That is why the frequency of cleaning is based on the
presence of water after a storm since the flow rate is reduced indicating maintenance
is required.
Reporting
Reports should be prepared as part of each inspection and include the following
information:
1. Date of inspection
2. GPS coordinates of Hydroworks unit
3. Time since last rainfall
4. Date of last inspection
5. Installation deficiencies (missing parts, incorrect installation of parts)
6. Structural deficiencies (concrete cracks, broken parts)
7. Operational deficiencies (leaks, blockages)
8. Presence of oil sheen or depth of oil layer
9. Estimate of depth/volume of floatables (trash, leaves) captured
10. Sediment depth measured
11. Recommendations for any repairs and/or maintenance for the unit
12. Estimation of time before maintenance is required if not required at time of
inspection
A sample inspection checklist is provided at the end of this manual.
Maintenance
Procedure
1. Water/Sediment Removal
Maintenance involves removing the water and replacing the filter cartridges. In both
cases, sediment that has been collected around the filter cartridges in the sump of the
device must be removed. This is typically done by vacuum truck.
It is important to remove all sediment and water from the structure before trying
to remove and replace the filter cartridges.
2. Filter Cartridge Replacement
Replacement of filter cartridges is made easy due to the modular nature of each
cartridge. The cartridges are stacked vertically on top of each other. Each cartridge
has a bell and spigot such that the fit together.

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A lifting bar is located In the center of the 6” hollow center of each cartridge near the
top of the cartridge. The top cone has a lifting ring on the top of it. Vertical stacks of
filters should have an access opening in the structure directly above them or close to
being directly above them.
A winch with a hook is lowered down to hook on to the cone lifting ring and the cone
is winched out of the structure. Similarly, the winch is hooked under the lifting bar of
each successive filter cartridge and they are winched out of the structure.
Fresh cartridges are similarly winched in stacking them as required ending each stack
with a cone. Call Hydroworks at 888-290-7900 since we offer a cartridge exchange
program.
The local municipality should be consulted for the allowable disposal options for both
the water and sediments that are removed from the HydroFilter.
Filter Cartridge Replenishment
Small HydroFilter units may be able to be replenished to extend the frequency of
replacement. Once the top cone is removed an inflatable pipe plug can be lowered
through the central core created by the connected filters to the base and expanded at
the bottom to seal the vertical core.
This vertical core or pipe can then be filled with clean water to backflush the filter
forcing it to flow from the central core opening back through the filter to the outside of
each filter cartridge. This backflush water can then be pumped or vacuumed from the
structure with the central core still being full of water.

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HYDROFILTER INSPECTION SHEET
Date
Date of Last Inspection
Site
City
State
Owner
GPS Coordinates
Date of last rainfall
Depth of rainfall (last 24h)
Site Characteristics Yes No
Soil erosion evident
Exposed material storage on site
Large exposure to leaf litter (lots of trees)
High traffic (vehicle) area
HydroFilter Yes No
Standing water (above 12” base) *
Missing internal components **
Internal component damage (cracked, broken, loose pieces) **
Floating debris in the structure (oil, leaves, trash)
Concrete cracks/deficiencies ***
Exposed rebar **
* Maintenance required
** Repairs required
*** Further investigation is required
Other Comments:
Please call Hydroworks at 888-290-7900 or email us at [e-mail] if you have
any questions regarding the Inspection Checklist. Please fax a copy of the completed checklist
to Hydroworks at 888-783-7271 for our records.

Hydroworks®HydroFilter
One Year Limited Warranty
Hydroworks, LLC warrants, to the purchaser and subsequent owner(s) during the warranty period subject to the terms
and conditions hereof, the Hydroworks HydroFilter to be free from defects in material and workmanship under normal
use and service, when properly installed, used, inspected and maintained in accordance with Hydroworks written
instructions, for the period of the warranty. The standard warranty period is 1 year.
The warranty period begins once the filter has been manufactured and is available for delivery. Any components
determined to be defective, either by failure or by inspection, in material and workmanship will be repaired, replaced or
remanufactured at Hydroworks’ option provided, however, that by doing so Hydroworks, LLC will not be obligated to
replace an entire insert or concrete section, or the complete unit. This warranty does not cover shipping charges,
damages, labor, any costs incurred to obtain access to the unit, any costs to repair/replace any surface treatment/cover
after repair/replacement, or other charges that may occur due to product failure, repair or replacement.
This warranty does not apply to any material that has been disassembled or modified without prior approval of
Hydroworks, LLC, that has been subjected to misuse, misapplication, neglect, alteration, accident or act of God, or that
has not been installed, inspected, operated or maintained in accordance with Hydroworks, LLC instructions and is in lieu
of all other warranties expressed or implied. Hydroworks, LLC does not authorize any representative or other person to
expand or otherwise modify this limited warranty.
The owner shall provide Hydroworks, LLC with written notice of any alleged defect in material or workmanship including
a detailed description of the alleged defect upon discovery of the defect. Hydroworks, LLC should be contacted at 257
Cox St., Roselle, NJ 07203 or any other address as supplied by Hydroworks, LLC. (888-290-7900).
This limited warranty is exclusive. There are no other warranties, express or implied, or merchantability or fitness for a
particular purpose and none shall be created whether under the uniform commercial code, custom or usage in the
industry or the course of dealings between the parties. Hydroworks, LLC will replace any goods that are defective under
this warranty as the sole and exclusive remedy for breach of this warranty.
Subject to the foregoing, all conditions, warranties, terms, undertakings or liabilities (including liability as to negligence),
expressed or implied, and howsoever arising, as to the condition, suitability, fitness, safety, or title to the Hydroworks
HydroFilter are hereby negated and excluded and Hydroworks, LLC gives and makes no such representation, warranty
or undertaking except as expressly set forth herein. Under no circumstances shall Hydroworks, LLC be liable to the
Purchaser or to any third party for product liability claims; claims arising from the design, shipment, or installation of the
HydroFilter, or the cost of other goods or services related to the purchase and installation of the HydroFilter. For this
Limited Warranty to apply, the HydroFilter must be installed in accordance with all site conditions required by state and
local codes; all other applicable laws; and Hydroworks’ written installation instructions.
Hydroworks, LLC expressly disclaims liability for special, consequential or incidental damages (even if it has been
advised of the possibility of the same) or breach of expressed or implied warranty. Hydroworks, LLC shall not be liable
for penalties or liquidated damages, including loss of production and profits; labor and materials; overhead costs; or
other loss or expense incurred by the purchaser or any third party. Specifically excluded from limited warranty coverage
are damages to the HydroFilter arising from ordinary wear and tear; alteration, accident, misuse, abuse or neglect;
improper maintenance, failure of the product due to improper installation of the concrete sections or improper sizing; or
any other event not caused by Hydroworks, LLC. This limited warranty represents Hydroworks’ sole liability to the
purchaser for claims related to the HydroFilter, whether the claim is based upon contract, tort, or other legal basis.